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5-2010
Optimizing Green Sand Properties of Fluidized Sand from Aeration and Developing New Green Sand Testing Technique
Ananda Mani Paudel Western Michigan University
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Recommended Citation Paudel, Ananda Mani, "Optimizing Green Sand Properties of Fluidized Sand from Aeration and Developing New Green Sand Testing Technique" (2010). Dissertations. 618. https://scholarworks.wmich.edu/dissertations/618
This Dissertation-Open Access is brought to you for free and open access by the Graduate College at ScholarWorks at WMU. It has been accepted for inclusion in Dissertations by an authorized administrator of ScholarWorks at WMU. For more information, please contact [email protected]. OPTIMIZING GREEN SAND PROPERTIES OF FLUIDIZED SAND FROM AERATION AND DEVELOPING NEW GREEN SAND TESTING TECHNIQUE
by
Ananda Mani Paudel
A Dissertation Submitted to the Faculty of The Graduate College in partial fulfillment of the requirements for the Degree of Doctor of Philosophy Department of Industrial and Manufacturing Engineering Advisor: Sam Ramrattan, Ph.D.
Western Michigan University Kalamazoo, Michigan May 2010 UMI Number: 3410416
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ProQuest LLC 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106-1346 OPTIMIZING GREEN SAND PROPERTIES OF FLUIDIZED SAND FROM AERATION AND DEVELOPING NEW GREEN SAND TESTING TECHNIQUE
Ananda Mani Paudel, Ph.D.
Western Michigan University, 2010
Aeration sand filling is a new molding technique in foundry. Using this technique, sand with smooth flow can be filled in any orientation and shape using low-pressure air. This is not possible by conventional gravity and high-pressure blow filling techniques. Aeration was introduced as an energy-efficient and environmentally- friendly sand molding technique. In addition, aeration has its niche on quality of molds it could produce. Friability, one of the crucial green properties for the quality mold was significantly low in aeration in comparison to the gravity and high-pressure blow filling. The fluidization action in aeration acted upon the sand clay interfaces and created the interactions with them, and induced better surface abrasive property. In other words, aeration lowered the friability in the green sand allowing a lower compactibility levels in green sand molding, which was not possible with the conventional molding techniques. The range of 30-35% was suggested as the optimal working range of compactibility for aeration molding technique for selected sand and clay composition.
Advance cone jolt and thermal erosion tester were developed and used to examine the green sand properties of the foundry sand. Advance cone jolt was sensitive to the clay composition and contamination in green sand, whereas thermal erosion tester demonstrated its relevance in evaluating mold surface behavior at an elevated temperature. Thermal erosion test displayed less sand erosion in the molds built in the aeration.
Green sand in aeration was benefited by the favorable clay orientation.
Homogeneous and isotropic distribution of clay platelets occurred during fluidization, which produced a better clay coating on the sand grains and increased the grain to grain bonding. Scanning electron microscope displayed a uniform clay coating and universal micro-tribometer showed greater bonding strength in the surface of the molds produced in aeration. Casting trial along with the relevant standard AFS tests for green sand properties were carried out, and analyzed using design of experiments and statistical tools. Copyright by Ananda Mani Paudel 2010 ACKNOWLEDGEMENTS
I would like to express my gratitude to my dissertation advisor, Professor Sam
Ramrattan for his patience, guidance and counsel throughout this research. This research also benefited from the numerous communiques and advice from Professor Pnina Ari-
Gur. I am thankful to Professor Steven Butt, Professor Leonardo Lamberson and
Professor Tarun Gupta for reviewing my work and providing valuable suggestions.
My special thanks to Dr. Hiroyasu Makino from Sintokogio, Japan for his support and technical assistance. I would like to thank Dr. Mitchel Keil, Mr. Deepak Ravindra and
Ms. Debbie Aliya for their help during the course of experiments and sharing technical expertise. I am equally thankful to Mr. Glen Hall, Mr. Peter Thannhauser and Mr.
Abraham Poot, for their technical support, and Mr. Kamaleshwaran Nagarajan, and Mr.
Rajiv Bharadwaj for their help in conducting the experiments.
Finally, I am grateful to my mom for her inspiration, and my wife, Puspa, daughter, Bhawana, and son, Aaron, for their sacrifices and continual support during these years of my study.
Ananda Mani Paudel
u TABLE OF CONTENTS
ACKNOWLEDGEMENTS ii
LIST OF TABLES ix
LIST OF FIGURES xi
CHAPTER
I. INTRODUCTION 1
H. LITERATURE REVIEW 6
Sand Molding Techniques 6
Gravity Filling 7
High-pressure Blow 8
Aeration Filling 9
Fluidizing Bed 12
Fluidizing Mechanism 12
Viscosity of Fluidized Sand 14
Molding Materials 15
Sand 15
Silica Sand 16
Olivine 18
Chromite 18
Ceramic Media 19
in Table of Contents-Continued
CHAPTER
Clay 19
Electrostatic Force 21
Surface Tension 22
Frictional Force 22
Water 23
Relationship between Clay and Moisture 24
Critical Bentonite Content 24
Water/ Effective Clay Ratio 25
Green Sand Properties and AFS Sand Test 26
Compactibility 26
Moisture Content 28
Bulk Density 28
Permeability 28
Green Compressive Strength 30
Splitting Strength 31
Mold Hardness 31
Percent Friability 31
Sand Toughness 33
Flowability 34
Volatility 34
iv Table of Contents-Continued
CHAPTER
Sand Control Program 35
Sand/Metal Ratio 37
Chemical Properties 37
Alternative Sand System 38
Friability in Green Sand 39
Casting Defects Due to Moisture 42
Water Explosion 43
Scabbing 43
Friability Related Casting Defects 46
Comments on AFS Standard Tests 46
Cone Jolt Toughness Test 47
Erosion Test 48
AFS Standard Testing Procedure 49
Preparation of Green Sand 49
Design of Experiments 51
Sand-Clay Interactions 51
X-ray Diffraction 51
Scanning Electron Microscope (SEM) 53
Universal Micro-tribometer 54
m. OBJECTIVE 56
IV. METHODOLOGY 60
v Table of Contents-Continued
CHAPTER
Design of Experiments 61
Decision Variables and Data Collection 64
Measure of Performance and Their Estimation 64
Determination of Minimum Number Replications 65
Analyzing Effects of Aeration and Comparison 66
Comparison of Multiple Alternative Sand Filling Techniques 66
Optimizing and Establishing Workable Range 68
Experimental Procedures and Setups 69
High-pressure Blow Setup 70
Experimental Setup for Aeration Sand Filling 70
Developing New Green Sand Testing Methods 74
Advance Cone Jolt Test 74
Thermal Erosion Tester 75
X-ray Diffraction Setup 77
Scanning Electron Microscope (SEM) Setup 78
Universal Micro-tribometer (UMT) Setup 78
V. RESULTS AND DISCUSSION 80
Results of Green Sand Test 82
Permeability 86
Green Compressive Strength 96
Mold Hardness 103
vi Table of Contents-Continued
CHAPTER
Bulk Density 110
Friability 117
Relationships between Friability and Compactibility 125
Comparison of Aeration with High-pressure and Gravity Filling 127
Validation of Friability Test Results 131
Implication of Lower Friability and Other Observations 132
Optimizing Green Sand Properties of Fluidized Sand in Aeration 135
Friability versus Other Green S and Properties in Aeration 161
Advance Cone Jolt 167
Test Results of Thermal Erosion Tester 169
Sand Clay Interactions in Different Filling Mechanisms 171
Results from X-ray Diffraction 171
Results of Scanning Electron Microscope (SEM) 174
Results of Universal Micro-tribometer (UMT) 175
Validation of the Findings 178
Molding and Green Sand Properties 179
Preparation of Green Sand to Desired Compactibility 180
Green Sand Properties 182
Experimental Matchplate and Gating Design 183
Design of Experiments 187
Measuring Erosion Depth 190
vii Table of Contents-Continued
CHAPTER
Conclusion and Recommendations 200
Benefits of Aeration Mixing 206
Limitations and Recommendations for Future Study 207
REFERENCES 212
APPENDICES
A. Data Collection Tables 217
B. Material Data Sheet of Various Sands 220
C. Experimental Data 221
D. Post-hoc Duncan Test Results 227
E. Residual Plots 231
F. High-pressure Blow Systems Verification Data 232
G. X-ray Diffractometer Setting and Results 233
H. Scratching Force High-pressure Specimen 234
I. Scratching Force Aeration Specimen 241
J. Normality Test of UTM Data 249
K. SEM and UTM Data 250
L. X-ray Diffraction Data 251
M. Green Properties Test Results of Various Sands in Aeration 284
N. Green Properties of Lake Silica Sand for Validation 286
O. Results of the Test Casting: Erosion Depth 287
viii LIST OF TABLES
1. Properties of Silica and Specialty Sands 17
2. Green Sand Testing Equipment 50
3. Factor and Level Codes for Design of Experiment 62
4. Environmental and Operating Conditions 63
5. Descriptive Statistics of Permeability 87
6. ANOVA: Permeability versus Sand, Technique, Compactibility 91
7. ANOVA of Individual Sand: Permeability versus Technique, Compactibility 92
8. Student-Newman-Keuls: Permeability 95
9. Descriptive Statistics of GCS Data 97
10. ANOVA: GCS versus Sand, Technique, Compactibility 99
11. ANOVA of Individual Sand: GCS versus Technique, Compactibility 100
12. Student-Newman-Keuls: GCS (lb/in2) 102
13. Descriptive Statistics of Mold Hardness 103
14. ANOVA: Mold Hardness versus Sand, Technique 106
15. ANOVA of Individual Sand: Mold Hardness versus Technique, Compactibility 106
16. Student-Newman-Keuls: Mold Hardness 108
17. Descriptive Statistics: Bulk Density (g/cm3) Ill
18. ANOVA: Bulk Density versus Sand, Technique 113
ix List of Tables-Continued
19. ANOVA of Individual Sand: Bulk Density versus Technique, Compactibility 114 20. Student-Newman-Keuls: Bulk Density (g/cm3) 116
21. Descriptive Statistics of Friability Data 118
22. ANOVA: Friability versus Sand, Technique 121
23. ANOVA of Individual Sand: Friability versus Technique, Compactibility. 122
24. Student-Newman-Keuls: Friability (%) 124
25. Friability Data for High-pressure, Aeration and Gravity 128
26. Comparison of Friability in Aeration, Gravity and High-pressure Blow 130
27. Cone Jolt Results for Aeration and Gravity 168
28. T-test of Cone Jolt: Aeration versus Gravity 169
29. Thermal Erosion Test Results 170
30. One-way ANOVA: Sand Loss versus Technique in Thermal Erosion Test 170
31. Intensity Ratio of Two Highest Peaks in Diffraction Pattern 173
32. Comparison of Scratching Force in Aeration and High-pressure Samples.. 177
33. Typical Properties of the Lake Sand 181
34. Properties of the Green Sand at 35% Compactability Level 182
35. Depth of Erosion in Different Sand Molding Techniques 194
36. ANOVA: Erosion Depth versus Squeeze Pressure, Head Height, Techniques 195
37. Student-Newman-Keuls: Erosion Depth (mm) 197
38. Summary of the Research Findings 210
x LIST OF FIGURES
1. Gravity Sand Filling 7
2. Aeration Filling Machine 10
3. Bed Expansion after Fluidization 13
4. Silica Sand Microscopic View 16
5. Various Types of Alternative Sands 19
6. Sand Particles Coated with Clay 20
7. Sand Testing Equipment 27
8. Green Sand Testing Equipment 29
9. Green Sand Test Equipment 32
10. Relationship between Friability and Clay 40
11. Relationship between Friability and Compactibility 41
12. Casting Defects 44
13. Casting Defects Due to Weak Mold 45
14. Sand Molding Process Flow 50
15. X-ray Diffractometer 52
16. Scanning Electron Microscope 54
17. Micro-tribometer Scratch Test 55
18. Schematic of High-pressure Blow System 70
19. Schematic of Aeration Sand Filling System 71
20. Experimental Matchplate with Half-section Sleeves and AFS Tubes 72
xi List of Figures-Continued
21. Aeration Sand Filling Pressure Curve 73
22. Advance Cone Jolt 75
23. Thermal Erosion Tester 76
24. Specimen Holder for X-ray Diffraction and SEM 77
25. Close-up View of Specimen Setup in UTM 79
26. Relationship between Moisture and Compactibility 83
27. Relationship between Compactibility and Green Sand Properties 84
28. Dotplot of Permeability 90
29. Permeability of Different Sands, Techniques and Compactibility Level 93
30. Dotplot of GCS 98
31. GCS of Different Sands, Techniques and Compactibility Level 101
32. Dotplot of Mold Hardness 105
33. Mold Hardness of Different Sands, Techniques and Compactibility Level 108
34. Dotplot of Bulk Density 112
35. Bulk Density of Different Sands, Techniques and Compactibility Level.... 115
36. Dotplot of Friability 120
37. Friability in Different Sands, Techniques and Compactibility Level 123
38. Friability of Silica Sands 126
39. Friability of Specialty Sands 126
40. Friability of Green S and with Different Filling Techniques 129
41. Boxplot of Friability Comparing Different Filling Techniques 129
xii List of Figures-Continued
42. Validation of Friability Results 132
43. Compactibility versus Green Sand Properties in Aeration 138
44. Relationship between Moisture and Compactibility 140
45. Bulk Density-Compactibility Relationship of Green Sand in Aeration 143
46. Moisture Content - Compactibility Relationship of Green Sand in Aeration 145 47. Permeability-Compactibility Relationship of Green Sand in Aeration 147
48. GCS-Compactibility Relationship of Green Sand in Aeration 149
49. Mold Hardness-Compactibility Relationship of Green Sand in Aeration ... 152
50. Friability-Compactibility Relationship of Green Sand in Aeration 153
51. Friability versus Green Properties of Lake S and in Aeration 162
52. Friability versus Green Properties of RG Sand in Aeration 164
5 3. Friability versus Green Properties of Olivine S and in Aeration 164
54. Friability versus Green Properties of Chromite Sand in Aeration 165
55. Friability versus Green Properties of Ceramic Media in Aeration 166
56. Advance Cone Jolt Test Results of Different Clays 168
57. Diffraction Pattern of Silica Sand and Clay Using Gravity Filling 172
58. Diffraction Pattern of Silica Sand and Clay Using Aeration Filling 172
59. Diffraction Pattern of Silica Sand and Clay Using High-pressure Blow 172
60. Intensity Ratio Interval Plot 173
61. SEM Picture High-pressure Blow Sand Specimen 174
xiii List of Figures-Continued
62. SEM Picture Aeration Sand Specimen 175
63. Scratching Force Plot in High-pressure Blow Specimen with Vertical Load 176
64. Scratching Force Plot in Aeration Specimen with Vertical Load 177
65. Schematic of Aeration Sand Molding System 180
66. Gating Design and Simulation Results 184
67. Test Flask with Cope and Drag Mold 186
68. Test Casting Process Flow Diagram 189
69. Non-contact Coordinate Measurement Machine 190
70. Erosion on Wedge Surface of the Test Castings 193
71. Sand Erosion and Resulting Irregular Casting Section 194
72. Interaction Plot for Erosion Depth (mm) 196
73. Friability versus Green Sand Properties of Olivine Sand in Aeration 209
xiv CHAPTER I
INTRODUCTION
Sand casting, the oldest manufacturing technique, is still popular among metal casters due to its low cost, high productivity and flexibility afforded by the molding process (Schleg, 2003). Among the wide variety of molding techniques in use today, green sand is by far the most diversified and widely used. Green sand in particular is of interest because it is available naturally and is environmentally friendly. The term "green" denotes the presence of moisture in the molding sand and indicates that the mold is not baked or dried. Molding techniques and sand control are the major contributors in quality and productivity of foundries. Development of newer molding techniques to get better castings from the green sand casting is continuing.
Various methods have been employed to shape green sand into molds such as gravity filling and high pressure blowing. Gravity filling and ramming is the traditional method, which is followed by gravity filling and squeezing. The majority of today's modern foundries use a high pressure blowing and squeezing technique to produce either horizontally or vertically parted green sand molds (Ramrattan, 2008). Lately, flaskless molding techniques are introduced. To improve the flowability and bonding of the green sands, various additives are introduced in the sand system (Kuz'min, 1987), (Lafay,
2009). However, none of the existing sand molding technologies has the capability to evenly fill or produce uniformly dense sand molds. Insufficient filling of sand to a complicated shape or deep pockets of small diameter will ultimately lead to casting
1 defects (Dietert, 1974). Aeration technique is proposed as a new sand molding method, which can fill complex shapes and produce uniformly dense molds. Aeration fluidizes the green sand before filling into the mold.
In aeration sand filling, green sand is mixed with air in a fluidizing chamber. The fluidized sand flows smoothly into the mold cavity with low pressure. This is a promising way to fill sand in any shape and orientation. Making molds with complex shapes and deep pockets is now possible (Hirata & Sugita, 2005). Further, the aeration technique is environmentally friendly because it produces molds with better green sand properties and eliminates the requirement of chemicals. Krysiak, et al, (2002) have shown that properly controlled green sand also can produce certain smaller near-net-shape castings comparable to chemically bonded sand. Casting quality is directly related to mold quality and mold quality largely depends on sand control.
Comparison of aeration filling technique with gravity filling and high-pressure blow techniques in terms of green sand properties signifies its worthiness. Over the years several noted papers on green sand system control are published with different approaches and views; however, focusing on the basic variables of green sand system is agreed on as the common theme for a successful sand control and comparison
(Ramrattan, Paudel, Makino, & Hirata, 2008). American Foundry Society (AFS) green sand control program identifies four basic variables as: addition of water, bond, new sand, and carbonaceous material (Krysiak & Pedicini, 1990), (Krysiak, 1990 & 1994). The basic sand tests identified to study green sand systems include compactibility, permeability, green strength, mold hardness, bulk density, and friability (AFS, 2000). The design of the experiment is devised and green properties tests are conducted in a controlled environment. Different types of sand compositions are studied. Out of these
2 batteries of sand test results, friability appears to behave differently in aeration with the interactions of other factors. Test results from this research can be useful for establishing reference green sand properties for the sand casting industry.
Sand control is essential, to produce world-class castings and meet the ever-increasing demands competitively, along with better quality and dimensional reproducibility (Bailey,
1983). Today's sophisticated molding equipment and control systems with a high level of automation hinder the understanding of how the green sand process works. A good understanding of the process is necessary to deal with day-to-day problems, and various operating parameters should be evaluated on a regular basis.
Each molding application has an established control range with respect to green sand properties (Knight, 1973). Logically, new molding technology, like aeration sand filling, requires processing parameters to achieve desirable green sand properties. These parameters need to be identified and measured using related AFS tests. In some cases more vigorous tests are required. Permeability, GCS, mold hardness, bulk density, and friability are selected as the major green property test to evaluate the mold quality produced in aeration. The relationship between these green properties with compactibility decides the optimal working range for aeration molding. Grain fineness number (GFN), sand distribution and clay content are maintained in the same level throughout the experiment while comparing the green sand properties, molds after filling is recycled for the next experiment without pouring the metal. This prevents the effects of the weight, heat and temperature of the metal on the green sand properties. Green sand properties will change if it comes in contact with the metal at elevated temperature. Clay particles will burn, and irreversibly converted into dead clay due to the enormous heat and temperature of the liquid metal. Dead clay loses its bonding characteristics; however, for the
3 validation of the green properties test results, a casting trial was conducted in the green sand molds produced with different molding techniques.
Although a long list of AFS standard green sand tests are followed by foundries, true control of the sand system is still not achieved. Thus, foundries are largely dependent upon the personal experience and hit and miss approach. The fundamental problem of the existing tests is the inability to capture the actual scenario of mold metal interface and dynamic nature of the mold making process. Currently, all sand tests are done in room temperature and it is well perceived that these tests cannot relate the actual situation of elevated temperature in casting. There is a need to develop new sand test procedures, which can bring the high temperature conditions into the test realistically. In experimental observation, friability has appeared as an interesting property, which behaves differently in the fluidized sand. To further study and investigate elevated temperature effects on friability, the thermal erosion tester is used, which measures the sand loss due to erosion at elevated temperature. Major AFS test such as green compressive strength are static in nature. The only existing dynamic test by the nature of loading is the cone jolt test, which has poor repeatability and accuracy. There is ample room for improvement in terms of accuracy and sophistication as well as efficiency of this test. The impact of fluidization in aeration on sand-clay interactions and resulting transformation in green sand properties are superior with that of conventional filling methods.
Material properties of sand clay mix under different filling techniques are studied in detail to understand the effect of filling techniques, and to explain the cause of the lower friability in aeration. Following approaches were used to analyze the impact of different filling mechanisms on sand-clay-water mix and green properties.
1. Chemical composition and microstructure analysis
4 2. Visual inspection of the clay plates in micro scale
3. Mechanical testing of sand clay bonding
X-ray diffraction helps to characterize the chemical composition and provides the information about the microstructure of the material. In sand clay mix, X-ray diffraction data is used to analyze the clay plate's orientation. Scanning Electron Microscope (SEM), another tool to study the materials in micro level, produces the structure of the clay pictorially. Micro-tribometer is used to measure the mechanical strength of the sand clay bonding.
5 CHAPTER H
LITERATURE REVIEW
In order to determine and select proper experimental methods and test procedures, a thorough review of relevant research is essential. In the same vein, to investigate the effects of aeration in green sand properties, researchers must understand the concepts of sand systems, theories behind the sand molding and common practices. This chapter is devoted to covering these aspects as the literature review of molding techniques and sand control. The first section relates to sand molding technique, which is followed by molding materials, green sand properties and casting defects.
Sand Molding Techniques
Sand casting is a cheap and simple metal casting technique. Sand, which is abundantly available and easy to form, is used to build the mold. Sand molds are popular among metal casters due to low initial investment to buy equipment, molds of different shapes can be made easily, and allow for faster design change. In addition, molding process has afforded higher productivity and flexibility. There are some limitations of sand casting in terms of accuracy, surface finish and shapes to be produced (Schleg,
2003). To eliminate these discrepancies and produce better quality castings with low cost, considerable effort has continually been made. Introducing new sand compositions and developing new molding techniques are some of the meaningful efforts.
6 Foundries in search of significant improvements in quality and productivity need to consider the molding system first. Improving molding systems results in better mold quality, which is the starting point for the journey of defect free castings. Various techniques were developed in an attempt to enhance quality of castings using sand moldings. These molding techniques can be broadly grouped into gravity, high-pressure blow and aeration filling.
Gravity Filling
This is a very primitive method of mold building. In this method, sand is mulled, riddled and fed into the flask manually. As the name gravity says, gravitational force drives the sand into the mold. Gravity sand filling process is shown in Figure 1.
Figure 1. Gravity Sand Filling
This is a simple way of sand molding and used by a small in-house foundry as well as big commercial casting companies. Low cost and easy to maintain are the chief
7 advantages of this molding technique. Low productivity and poor reproducibility hinders its application in high quality large volume castings.
High-pressure Blow
In the high-pressure blow technique, green sand after mulling is transferred into the flask with the help of high-pressure air shot (0.6 MPa). First, sand is delivered to a single location, acting as a feeder for a common blow tank. Sand from the blow tank is filled into the top of the cope and bottom of the drag of the mold at the same time. This design assures 45 to 55 mold hardness prior to the squeeze. Filling density is higher than gravity. As sand is blown into the mold cavity, less sand movement occurs during the squeeze cycle, which helps in reducing pattern wear. In addition, the blow-fill system has less sand spill than gravity fill. High-pressure molding practice also reduces moisture contents in the molding sand to get higher mold densities. Lately, with the aid of flaskless molding, the inventory of mold flask is eliminating in high-pressure blow molding lines (Schleg, 2003).
In conventional flaskless molding, sand filling methods such as gravity, "top and bottom blow" or "side blow" with the aid of high pressure compressed air are popularly used. The conventional top blow, particularly with vertically positioned matchplate shows stable sand filling in wide varieties of molding sands. In North America, almost 90% of the sand casting foundries use high-pressure blow molding technique (Ramrattan, 2008).
The development of newer techniques have demonstrated considerably better improvements in dimensional accuracy along with improved surface finish, closer to pattern accuracy and increased productivity (Bex, 1992). At the same time, extensive
8 maintenance and high-energy consumption by the high-pressure machines has raised the cost of production. Further, these techniques have limitations in the shape they can produce. They result insufficient sand filling in complicated shape and deep pockets of small diameter, and lead to casting defects (Hirata & Sugita, 2005).
Aeration Filling
Aeration filling technique is based on fluidization process. Fluidization is used in various industries for different applications such as mixing and transferring powders in pharmaceuticals and material transfer in casting industry (Bakhtiyarov, 1996a; Rhodes,
2001). However, the application and mechanism of fluidization is different. In sand molding, fluidization has recently been studied. In sand molding applications, green sand is fluidized by air and coined the name aeration molding technique for the process. In the aeration technique, green sand is first fluidized, which greatly increases its flowability, and low-pressure air applied afterwards drive it into the mold with smooth feeding.
Aeration filling uses green sand and offers a means that can fill a mold in any orientation.
Hirata et al., (2005) showed that complete sand filling and uniformly dense molds are possible by aeration. Furthermore, since the area of the blow nozzle is large, the speed of sand projection through the nozzle is much lower than conventional high-pressure blow method. Consequently, in aeration sand filling, sand with low density falls on the pattern surface slowly and gently, as opposed to being blasted out at high speeds of high- pressure blow. Accordingly, bridge-forming phenomenon at the area with complicated shape patterns and at the mouth of small size pockets is minimized. The sand streams down smoothly toward the vent plugs furnished at the bottom of each pocket riding on the
9 aeration air, and sand bulk density is further increased by airflow effect. The composite action of these effects makes it possible to achieve high-density sand filling to the areas with complicated configuration and pockets having a small diameter. Even with the air pressure much lower than blowing, the bulk density obtained in aeration is generally higher. It is considered that a decrease in friction resistance at the aeration filter area has contributed to achieve a higher bulk density. The effect of airflow acting on each sand particle increases the kinetic energy of the sand particles, and results in the achievement of higher bulk density (Hirata, 2002).
Hirata, (2002) has discussed the design and describes the technology for an aeration sand filling system, which is shown in Figure 2.
Figure 2. Aeration Filling Machine
10 As shown in Figure 2, aeration system consists of aeration chamber, air handling or inlet manifold, air tank, and pressure and time control module.
The aeration sand filling system makes it possible to fill sand into complex shapes, deep pockets, and thin sections on a matchplate that heretofore were not possible by conventional molding method such as high-pressure blowing. Hirata et al., (2005) has made significant findings with respect to aeration filling of sleeves. Generally, the larger the inside diameter of the sleeve the higher the filling density will be. However, the lower the aeration pressure, the higher the filling density becomes, especially in the small diameter sleeve.
When aeration air pressure is low, sand flows slowly and smoothly, filling the sleeve cavity in an orderly manner. On the contrary, at higher-pressure blow, sand builds up a bridge at the inlet area, and later, as the bridge collapses, the sand tries to fill the cavity in a series of surges resulting in unequal density distribution. Further, when the vent area at the bottom part of the sleeve is increased, filling density becomes higher.
This improvement of filling density is caused by an increase in volume of smooth airflow streaming through the sleeve. The increase of smooth airflow volume causes to increase the speed of sand stream, and results in the uniform filling from bottom to top giving improved density. In summary, followings are the features of aeration sand filling (Hirata
& Sugita, 2005)
• Complete mold filling and uniform density distribution
• Can fill a mold in any orientation and position
• Smooth sand feeding can produce smooth surface finish
• Bridge-forming phenomenon due to the change in cross-section area is minimized
11 • Possible to achieve high density even with much lower air pressure (Hirata, 2002)
• High productivity with 200 molds/hour
• Lower noise level due to lower air pressure in use
Fluidizing Bed
Fluidization is a process by which materials with fine solid particles are transformed into a fluid-like state through the contact with a gas or liquid (Kunii & Levenspiel, 1991).
Fluidized beds are known for their high heat and mass transfer coefficients due to the high surface area-to-volume ratio of fine particles. Fluidized beds are used in a wide variety of industrial processes such as reaction, drying, mixing and granulation, coating, heating, and cooling.
Fluidizing Mechanism
When trying to describe the operation of a fluidized bed, fluidization velocity is a crucial parameter to start with, which is defined as the superficial fluid velocity at which the upward drag force exerted by the fluid is equal to the apparent weight of the particles in the bed. Another common characteristic of fluidized beds is the bed expansion. When incipient fluidization is achieved, the fluid flowing upwards pushes the particles up and the separation distance between particles increases. This increases the void volume within the bed of particles and the bed is expanded (Bakhtiyarov, 1996b).
Mathematical model that describes the flow of a fluid through a bed of particles is constructed under the assumption that the bed behaves as a group of tubes, which follows
12 a tortuous path. Carman-Koseny studied the behavior of randomly packed bed of mono- sized spheres in laminar flow regimes. Ergun equation is used for the flow calculation
(Rhodes, 1998).
At minimum fluidization, pressure drop of a packed bed and the one of a fluidized bed are the same. In laminar flow (Reynolds number (Re) < 10) the pressure gradient increases linearly with superficial fluid velocity and remain independent of fluid density.
Under turbulent flow (Re > 2000) conditions, the pressure gradient increases as the square of the superficial fluid velocity and is independent of fluid viscosity. When a fluid passes upward through a bed of particles, pressure of the fluid decreased with increasing flow due to frictional resistance. A point is reached when the upward drag force exerted by the fluid on the particles is equal to the apparent weight of the particles in the bed. The pressure drop of the gas flow is originated by the friction of the gas with
"walls of tortuous channels" and by the drag force of moving particles (Rhodes, 1998). A schematic of an expanded bed is shown in Figure 3.
Initial Expanded
i •?••.•-•.•••.•."."'•.•»"/•* i Expansion _ . %"V«%»S"SS >i"'^"»"-."" .••«••=& t •v-V-V-V-v-V-lh t,.i-. a S . % •i \ -1S • S « if »«•»••••••••" W"a"i ?.""»a"»" »••••••»'»* hi t^i'^i"2i*£.«"£*'l.a& f • %*« torinrirvnrife tfi-tf 4
Air
Figure 3. Bed Expansion after Fluidization
13 As shown in Figure 3, when air is introduced into the chamber through a porous media, the level of the sand in the chamber is increased. Due to the fluidization effects of the air, mass of the sand is expanded giving rise in volume, and increases the sand level in the chamber.
Several research studies can be found in the literature regarding the mechanism of fluidization and which investigate the effects of various factors such as temperature and viscosity. Those parameters and factors are enumerated and used to develop numerical as well as, analytical models (Bakhtiyarov, 1996).
Viscosity of Fluidized Sand
In a study done by Bakhtiyarov, 1996, using Brookfield viscometer shows that as either the shear rate or the bed voidage factor (air flow rate) increases, the apparent viscosity decreases. In addition, viscosities are slightly affected by changes in particle diameter. Apparent viscosity does not depend on the overall pressure drop of a given capillary tube although it is affected by tube length to inner diameter ratio (Bakhtiyarov,
1996). Fluidization is used in various industrial applications.
One of the industrial applications of fluidization is material transfer. The powder dosing is achieved without screws. For this purpose efficient fluidization is achieved by using air flowing in small quantities, and evenly distributed, through specially designed fluid elements in the conical section of the silo. Fluidization process creates the flow of material by lowering the friction between the silo wall and the powder as well as between powder particles. The system keeps the material flow even and non-segregated in the silo
14 without dust and pressure built up. The air consumption in this system is very low and the existing air pressure system is enough to operate. Good silo discharge is possible for fine dry raw materials such as fine sand, limestone powders, cements, burnt lime and various dry powder chemicals with great saving. The fluidization takes place in two simultaneous ways: first, a thin "film" of air between the hose wall and the powder material reduces friction, and then air enters into the powder fluidizing the individual particles. The fluidized powder material flows by its own weight when the hose is slightly inclined (3 to
6 degrees). Compared with screw conveyors, the fluid hose has significant advantages such as high capacity, space savings through flexibility in routing and installation, and low maintenance due to the absence of moving parts (Rhodes, 2001).
Molding Materials
Sand, clay and water are the primary materials used in green sand molding. Other additives, which are used to improve moldability and green properties in foundries, are not included in this research.
Sand
Selection of suitable sand is the first step of mold making process in sand casting.
Sand is a mineral of any chemical compositions with the sizes from 0.1 to 0.002 mm
(Bralower & Granlund, 1989). Silica, olivine and chromites are commonly used sands in foundries. Ceramic media is gaining popularity among the foundrymen today.
15 Silica Sand
Silica is essentially SiC>2 (silicon dioxide) and used most extensively in foundries due to its abundance and low cost. Melting point of silica sand is approximately 1787°C
(3250°F), which is normally above the pouring temperature of most alloys poured in foundry. It has satisfactory thermal conductivity with high thermal stability. Silica sand is wetted, covered with the liquid or molten metal, and fluxed with iron approximately at
1226°C (2240°F). Silica is considered effective foundry sand because of its resistance to metal and acid reactions (Bralower & Granlund, 1989). Long time exposure of silica causes silicosis, a respiration disorder. Two types of silica sand are normally used in foundry: lake sand and round grain (RG). Pictures and properties of silica sand grains are shown in Figure 4 and Table 1, respectively.
a) Lake sand b) Round Grain Sand
Figure 4. Silica Sand Microscopic View
Lake sand is mined from lakeshore, mainly from the shores of the Great Lakes, surrounding Michigan. This sand contains entrapped materials and thus is not pure.
16 Contaminants are iron oxide, rootile, calcium carbonates and other organics. RG Silica
sand on the other hand is considered pure silica and is mined from St. Peter deposits found in Illinois and Missouri. Pure silica sand is round in shape and lake sand is sub- angular.
The shape of the sand grain has an effect on the amount of binder or bonding material required to hold the sand grain together, ability to compact the sand grain together and the permeability of the mold. Rounded sand requires less binder than sub- angular with angular requiring the most. Because spherical shape has the least surface to volume ratio and require less clay to coat the surface. Also the ability to compact the sand grains together is either helped or hindered by the grain shape. Round grains are compacted very well, whereas angular grains are difficult to compact (Bralower 1989).
Table 1. Properties of Silica and Specialty Sands
Round Ceramic Sand Lake Grain Olivine Chromites Media Origin Michigan Illinois Washington South Africa Manufactured Color Light brown White Greenish gray Black Gray Shape Sub-angular Rounded Angular Compounded Round Density (lb/cu ft) 85-100 85-100 98-103 155-165 120-130 Fusion Point (°F) 1600-2700 1600-3200 2800-3200 3200-3600 >3400 AFSGFN 60 60 60 60 60 Grain distribution 4 sieve 4 sieve 4 sieve 4 sieve 4 sieve Application Non- ferrous All Non-ferrous Steel All & Cast Iron
Sub-angular and angular sand grains when compacted to the same density, will offer better mold permeability than round sand grains. Sub-angular and angular sand grains are better equipped to accommodate the sand grain expansion that will take place when sand is heated by the molten metal (Schleg, 2003).
17 Olivine
Olivine sand is an ortho-silicate of magnesium and iron, occurring in nature as forsterite and fayalite. Melting point of olivine is approximately 1871°C (3400°F) slightly higher than silica. Olivine exhibits somewhat lower thermal expansion characteristic than does silica; thus, it has good stability compared to silica. It has angular grain shape and is more expensive than silica because of its limited availability. Cleaner casting is one of the major benefits of olivine. Olivine has very low permeability but strong molds with high compaction can be achieved without hurting permeability. High-density compaction helps in dimensional accuracy of the castings (Bralower, 1989). Grain shape and properties of olivine sand are shown in Figure 5(a) and Table 1, respectively. This sand is primarily used in the nonferrous foundry; however, it can be used in steel and cast iron.
Chromite
Chromite is mined in Africa, and is expensive in North America due to the high shipping cost. It comes in compounded angular shape. Chromite has higher refractoriness and less thermal expansion than silica sand. Further, it exhibits good chilling characteristic, which adds on preventing shrinkage defects and hot spots (Bralower,
1989). Grain shape and properties of chromite sand are shown in Figure 5(b) and Table 1, respectively. This high-density sand serves better for thick section castings with higher density such as steel and cast iron.
18 a) Olivine b) Chromites c) Ceramic media
Figure 5.Various Types of Alternative Sands
Ceramic Media
Ceramic media is extracted from oil fields. Bulk density and specific gravity of ceramic media is similar to silica sand. This molding material is particularly advantageous due to its high conductivity and chemical inertness. It is more cost-effective than resin coated sands (Schleg, 2003). Figure 5(c) shows the picture of the ceramic media and its properties are displayed in Table 1.
Clay
Clay is another crucial material for sand casting industry. It is extensively used as a bonding material. A clay requirement in sand molding is next to the sand, by volume.
Most of the clay used in foundry is bentonite clay, which is composed of
Montmorillonite, chemically, it is hydrated sodium calcium aluminium magnesium silicate hydroxide (Na, Ca)0.33(Al,Mg)2(Si4Oio)(OH)2-nH20. Montmorillonite is a highly colloidal and plastic material. Sodium bentonite, commonly called the western
19 bentonite, is noted for its affinity to water, which gives it a tremendous swelling property.
Sodium bentonite can absorb water from 7 to 10 times of its own weight, and swells up to
18 times its dry volume. Sodium bentonite contains exchangeable sodium cations. When dispersed in water, it breaks down into small plate-like particles negatively charged on the surface and positively charged on the edges. This unique ion exchange is responsible for binding action. Sodium bentonite clay provides high hot strength and is used mainly in ferrous castings. Calcium bentonite, which is also called southern bentonite, has lower hot strengths in green sand. The lower hot strength provides excellent shakeout properties. Calcium bentonite has slightly higher green strength than sodium bentonite. It also requires less mulling energy to get water into the clay particles and evenly distributes and develops clay coating to the sand grains. Clay-coated sand is shown in Figure 6.
Figure 6. Sand Particles Coated with Clay
Calcium bentonite may be converted to sodium bentonite by ion exchange and exhibit sodium bentonite's properties. By adding 5% -10% of sodium carbonate to wet calcium bentonite, mixing well, and allowing for some time for ion exchange, and it will
20 be converted into sodium bentonite (Sanders, 1970). Calcium and sodium bentonite combinations are used in the most cast iron foundries.
Bentonite particles's small plate-like shape provides greater surface area. Its structure is much like a sandwiched deck of cards. When placed in water, these cards or clay platelets shift apart. Bentonite attracts water to its negative face and magnetically holds the water in place because of this unique characteristic. The bonding forces involved in holding particles of clay and sand together are based on several theories: electrostatic, surface tension and interparticle friction (Schleg, 2003); (Boenisch, 1988).
Electrostatic Force
Electrostatic forces appear with the presence of electric charges in the materials.
In clay, dipolar forces operating at the sand-clay and clay-clay interfaces define this force.
Adsorption of positive ions by water and negative ions by hydrated clay surface creates the dipolar action. When water is added to dry clay, the negative ions are adsorbed on the nuclei of the clay atoms. The positive ions are attracted by the negative ions, but repelled by the nuclei of the clay atoms. Then positive ions take up the resulting equilibrium positions. Water forms neutralized clay micelles. Kinetic energy of these micelles causes the movements. Force of attraction between positive ions themselves and the nuclei of the clay particle induced. As the distance between the clay micelles increases, an intermicellular force results with the force of increases in attraction and decreases repulsion. The bond strength increases with increasing amount of water to a certain point of a maximum value called tempering point and then starts to drop. Additional
21 water entering between the dipoles pushes clay plates far away and results the decreases in net intermicellular force and weaken the bonding (Schleg, 2003).
Surface Tension
Surface tension develops in a liquid medium. In green sand due to the presence of water surface tension develops around the clay and clay sand particles, and aids in bond strength. The interstices of the clay particles are filled with water. Surface layers of water act on a stretched membrane of hydrated clay develop cohesive force binding the clay particles together. The amount of water in the green sand reduces in drying, and the force holding the clay particles together increases (Schleg, 2003).
Frictional Force
Friction occurs between the sand grain surfaces and resists their movement, which helps in binding. Interparticle friction depends on the geometry of the sand grain, irregular shape offer more friction than the rounded. Interparticle friction or the so-called block-and-wedge effect induces in the materials under pressure. When molding sand is rammed inside a flask, sand particles get jammed against one other. Packing action, which support the sand grains within the flask by interlocking happens with the favorable orientation of sand grains (Schleg, 2003).
In summary, bentonite is the primary bonding material used in sand molding.
When mixed with foundry sands, bentonite forms a pliable bond with the sand granules.
Mold cavities are formed using bentonite/sand mixtures where molten metal is poured at
22 a temperatures ranging from 1200° F to 3000°F depending upon the type of the metal.
Castings with the shape of the mold cavity are obtained after solidification. The unique bonding characteristics of the bentonite insure durability of the mold during high temperature metal pouring and solidification. Further, it holds the weight of the casting when metal solidifies. After completing this process, green sand molds are broken down.
Castings from the mold are retrieved and sent for secondary processing, whereas green sand is reclaimed and reused.
Bentonite is equally popular in a variety of other applications such as landfill sealing, biological and clinical procedures. It is also used as a major constituent in various products: cement; adhesives, ceramic bodies, cosmetics, cat litter etc. Moreover,
Bentonite is uniquely useful in the process of winemaking (Bentonite, 2007)
Water
Water affects almost every physical and mechanical property of the green sand. In green sand, water exists in two forms. One is free moisture, which can be removed by drying. Another is rigid water, which is absorbed and contained inside the clay particles, and can only be removed by heating to a high temperature (Schleg, 2003). Water in an amount of one and half to eight percent activates clay in green sand, and causes the aggregate to develop plasticity and strength. Water in molding sand is often referred as tempering water. This is basically the absorbed rigid water. Only the tempering water appears to be effective in developing strength. Any excess moisture absorbed by clay exists as free water. Free water acts as a lubricant, making the sand more plastic and moldable, though it may lower the strength (Boenisch, 1988).
23 Relationship between Clay and Moisture
A proportion of water and clay plays a vital role in determining strength and other characteristics of the green sand. Controlled amounts of water and clay serve better for optimal performance of the sand system. Effective use of clay saves cost and increases quality.
Critical Bentonite Content
The amount of clay in green sand is crucial to achieve desirable green properties.
If molding sand contains less than about 6% active bentonite, its properties cannot be improved by increasing moisture. Concentration higher than this "critical bentonite level" can only raise deformation limits of well-tempered green sands to obtain better molding properties. For this reason, production sands generally contain about 8% to 12% of active bentonite (Boenisch, 1988). Effective use of clay and its consumption depends upon the procedure of sand preparation. Short mulling times and too low temper point moisture levels often reduces the clay effectiveness. Moreover, temper point moisture level of production sands is decreased significantly since the introduction of high-pressure compaction. At the same time, swelling and dispersion of bentonite, and integration of sand grains are impaired (Boenisch, 1988). Additional bentonite consumption is inevitable to ensure satisfactory molding properties. Foundries have attempted to improve this situation by using additives. In any event, organic additives are inferior sand binders, and cannot replace bentonite. The demands of high pressure compaction and increasing use of synthetic, resin-bonded sand cores have lowered the molding sand properties. In
24 addition, brittleness of green sand molds is becoming a major problem. High level of active bentonite and other clay substances are obligatory to cope with this situation. These substances reduce refractoriness of the molding sand, and increase the danger of reactions between metal and molding sand. This in turn, compels the development and use of highly active, lusturous-carbonforming additives at a high level. Oily products of this type stick the bentonite particles together and reduce clay's swelling capacity. Further, such organic additives make molding sand more acidic and cause additional damage to green properties (Sanders, 1970).
Water/Effective Clay Ratio (WECR)
WECR defines the temper point of molding sands. Sand is said to be at its temper point when it has a water/effective clay ratio corresponding to its maximum strength and minimum density in a pure sand-clay-water system. This ratio is crucial, and plays a major role in determining the sand system's characteristics such as compactibility, deformability, moldability, maximum tensile strength, and shatter/compression strength ratio (Roshan, 1975). Effective clay ratio (ECR) is given by:
AC ECR= Equation 1 TC
Where, AC is Active clay and TC is AFS total clay
The ratio of clay to water required for a clay-bonded sand mixture is a function of:
1. Sand grain distribution or surface area
2. Type of clay and composition
3. pH of the green sand 25 4. Duration of mixing and mulling efficiency
5. Presence of other additives and contaminants
6. Temperature of the green sand mixture (Philips, 1970)
The temper point of a sand mixture or the relationship of the water clay ratio and its effects on sand properties of a typical foundry sand mixes was demonstrated by Vingas
(1954).
Green Sand Properties and AFS Sand Test
Green sand is an aggregate composed of sand, clay, other additives and water.
Properties of the green sand depend upon the type and amount of materials used, method of mixing and mulling, and other environmental factors. Various green properties are defined for evaluating the sand system and control the molding process. Compactibility, flowability, volatility, toughness, permeability, strength, mold hardness and friability are some of the major green sand properties. The following standard AFS tests are carried out in foundries to measure the respective green properties.
Compactibility
Due to the swelling characteristics of the clay, volume of the green sand changes along with the change in water addition. Compactibility, which is expressed in percentage, measures the change in volume of green sand on compaction. The AFS compactibility test determines the percentage decrease in height of a loose mass of sand in an AFS tube. The procedure consists of filling the tubes with sand, and applying a 14
26 lb ram three times. The amount of compaction is directly read from a linear scale in 3-ram
(AFS, 2000). Lately, the squeezing method is also used to check compactibility, in which, sand in AFS tube is squeezed with the pressure of 140-psi for three seconds. A squeezer, which is used for the green sand compaction for compactibility measurement, is shown in
Figure 7(a).
a) Pneumatic Squeezer b) Moisture Content Test Equipment
Figure 7. Sand Testing Equipment
Compactibility is one of the most important green sand properties. Compactibility values are directly related to the performance of the sand in molding. Change in sand parameters changes the water requirements for tempering, which is detected by compactibility. Thus, it provides a way to measure the degree of temper of the molding sand (Bralower, 1989). Due to its responsiveness to detect any changes in sand system, compactibility is used as a baseline to control and compare sand systems. In this test procedure, sand is riddled through a quarter inch sieve and filled the specimen tube. The green sand filled tube is placed under the squeezer plunger and the sand is compacted
27 with the preset pressure of 140 lb/in2. The amount of compaction is reported as
compactibility percent.
Moisture Content
This test measures the amount of water in green sand. In a standard AFS procedure, 10 grams of a green sand sample is heated at 150°C for five minutes, and moisture content is calculated as a percentage loss in weight of the sand sample after heating. Moisture content is directly related to compactibility. Moisture testing equipment is shown in Figure 7(b).
Bulk Density
Sand filled in an AFS tube is weighed and density is calculated as mass per unit volume. Bulk density of the same green sand may be different for different molding techniques. Methods such as high-pressure blow have higher bulk density than gravity fill. Due to the high pressure, green sand is compacted and produces high density.
Permeability
Permeability measures the venting characteristics of green sand. Permmeter employs the orifice method for the rapid determination of sand permeability. Air at a constant pressure is applied to a standard test specimen (AFS tube), and the drop in pressure with respect to time is measured on a pressure gauge, which is calibrated directly in
28 permeability numbers. Permeability is inversely proportional to the time for pressure drop. If a green sand sample takes more time to get air to pass through, it is less permeable. Sand with higher permeability numbers releases the air faster. Permmeter measures the permeability, which is shown in Figure 8(a).
a) Permmeter b) Compressive Strength Test
Figure 8. Green Sand Testing Equipment
The following equation is used to calculate permeability (P) (AFS, 2000).
vxh P=- .Equation 2 pxaxt
For the standard AFS test procedure
Air volume (v) = 2000cm3
Pressure head (p) = 10 gm/cm2
Specimen height (h) = 5.08 cm
Specimen area (a) = 20.27 cm2
29 Time (t) is in minutes
After substituting respective values of the parameters, permeability equation will be
as follows:
Or P = /q- Equation3
With K = 50.123
Green Compressive Strength
This test measures the bearing capacity of a mold during compression load. The test machine is designed to determine compression strength of an AFS standard specimen of green sand by applying a progressively increasing spring load to the specimen until it collapses, and ultimate compressive stress is recorded and displayed in lbs/in . Figure
8(b) shows the compressive strength test equipment. Standard AFS specimen is mounted on the specimen post and is raised against the cantilever load cell, which measures the pressure on the specimen, and the control module record the highest value of the pressure and displays as an ultimate strength.
A mold should be strong enough to withstand the different impacts during handling and transfer from the molding station to the pouring station, as well as other impact loads that might occur in the process. Green strength of the mold is the ability to stay together until it is filled with molten metal; hot strength, on the other hand, is the ability of the mold to hold the shape and contours of its internal cavity until the casting has turned completely into a solid.
30 Splitting Strength
According to AFS, splitting strength is the measure of maximum diametral- compressive stress. The same compressive strength test equipment is used in this test procedure. The only difference is the way in which the specimen is mounted. Instead of an upright position, as in the compressive strength test, the test specimen is lying down horizontally in this procedure.
Mold Hardness
Mold hardness gives the mold surface hardness. In the standard AFS procedure, mold hardness is measured as the resistance to the penetration of a loaded plunger by the surface of the green sand mold. This test basically quantifies the degree of ramming. The principle of this test is similar to the Brinell hardness test. Mold hardness test instrument is shown in Figure 9(a).
Percent Friability
The friability test measures the ability of a compacted molding sand to resist abrasion or scuffing in the first few millimeters at the surface of the mold. Two AFS standard specimens each with a two-inch diameter and a two-inch height (50.8 mm x 50.8 mm) are placed side-by-side in a seven-inch diameter (178 mm) cylindrical screen, and rotated with the speed of sixty revolutions per minute. The specimens are rubbed against each other as well as against the screen of the drum. The amount of sand abraded from the
31 specimens after one minute is collected and weighed. The weight of loose sand removed from the specimen is divided by the original weight of the specimens and multiplied by one hundred is expressed as the percent friability as shown in Equation 4. Figure 9(b) shows the friability test equipment.
Initial Weight Friability = x 100% Equation 4 Initial Weight- Final Weight
a) Mold hardness Test b) Friability Test
Figure 9. Green Sand Test Equipment
Low friability is desirable to maintain mold edges, corners, parting lines and mold surfaces, which otherwise can be damaged or abraded during molding, core setting, handling and metal pouring. A friability value above 11% indicates a tendency to produce dirt defects and loss of casting surface quality. Foundries normally try to keep friability less than 10% by maintaining 35%-40% compactibility levels.
32 Sand Toughness
Toughness is the ability of the sand mold to withstand the impact load incur during molding and handling in production lines. This property depends upon the various parameters and their interactions, and this green sand property helps foundrymen to monitor the changes in the sand systems such as:
1. Quality of the bond
2. Condition of sand mixer if it needs maintenance
3. Degree of mixing and sufficient mulling
4. Proper composition of clay and sand
5. Moisture content or compactibility (Somers & Melcher, 1973)
Toughness of the green sand increases with the increase in moisture almost linearly. Similarly, the higher the moldability, the tougher is the mold. But the relation is non-linear. If the compactibility increases, toughness will also increase. Mold hardness and toughness are also directly related. Compressive strength goes up with toughness to some extent but after an apex in tempering point, green compressive strength starts to decline while toughness still goes up (Dietert, 1974). Strength tests such as compressive, tensile, splitting and shear all measure the static strength of molding sand, whereas cone jolt measures dynamic strength. Cone jolt is sensitive to certain ingredients such as cereal binders, clay type etc.
Toughness is generally measured by cone jolt test equipment. A standard test specimen having a cone shape recess on the top surface is loaded with a cone of constant load and jolted on a resting anvil. The cone tip penetrates into the specimen during the
33 jolting and the number of jolts before failure is recorded and expressed as a toughness measure.
Flowability
Sand is a free flowing material when dry. It losses this ability when mixed with water. Addition of clay makes it sticky and coherent. Sand should display very little coherence and fill a flask, as if it was completely dry. As soon as the grain starts to show coherence, sand will flow in and around the pattern. The coherent sand conglomerates, and forms bridges over the opening leading to such space. Subsequent squeezing compaction moves sand a little but not enough to compensate that shortage, so that the density of the mold in those places is lower than elsewhere. In modern molding lines, flow properties of sand in the loose state are therefore very important. The flowability test measures this tendency to cohere and form a bridge in the green sand. Increasing the moisture content greatly reduces flowability because the tendency of grains to stick together will be increased (Levelink, VandenBerg, & Frank, 1973).
Volatility
Green sand comes from nature (mines, beaches, dunes etc.), and thus it inherently contains various organic materials. In addition to these natural sources of organic material, other additives are added to enhance certain green properties during the molding process. These organic materials evaporate well below the melting temperatures of the metal, and the gases generated in the mold can penetrate and trap into the molten metal,
34 which produces gas defects. The common carbonaceous materials in molding sand are cereal, seacoal pitch and wood flour. Control of these additives can be achieved by determining volatility and loss-on-ignition. The volatility test will indicate the amount of the light and heavy oil fractions derived from various organics in the green sand mix.
Volatility fraction is determined by the use of a Meker burner, using a five grams sample of sand mixture (AFS, 2000).
Sand Control Program
Knight (1973) studied sand control systems for high-pressure blow molding. He had looked into permeability, bentonite, hardness, moisture and clay content and flow ability of the green sand (Knight, 1973). Morgan (1973) investigated the impact of mulling time, temperature and relative humidity to each green sand property. In addition, he outlined the optimal range for these parameters (Morgan, 1973). Later, Dietert (1974) proposed seven sand tests procedures for sand control. He developed a test program for the control of foundry system sands, which was evaluated and applied in a number of foundries over a four-year period. In this program, compactibility, moisture, specimen weight, permeability, green compression, splitting strength and methylene blue total clay were assigned as daily tests. A relationship was derived to calculate both effective and latent clay contents from these tests along with mixing efficiency. Two combustibles tests were also purposed to carry out weekly. One test occurs at 1800° F using residue from
AFS clay wash and the other is the volatile test at 900° F. AFS clay determination was
35 also an additional proposed tests (Dietert, 1974). All these tests are still widely used in foundries today.
Radhakrishnan, (1975), did a study of physical properties of bentonite-bonded molding sand. He suggested that various green properties (i.e. compression and shear strengths, hardness, permeability, bulk density, flowability, compactibility) of synthetic molding sand could be expressed as a function of clay and water. It was claimed that these equations could also be used for establishing the interrelationship between the properties of any given molding sand (Radhakrishnan, 1975). In a paper "Understanding
Green Sand: A Review", Joseph Ricardo (1980) advised operating foundrymen and other metalcasting technicians to review the basics of the processes and materials that they work with every day. These process basics provide a good in-depth knowledge of molding medium, green sand, its major constituents and factors that controls sand system effectiveness. Sand specifications and the relation of these specifications to casting defects were also examined (Ricardo, 1980). Similarly, Schumacher (1983) studied the sand properties in foundry laboratories of International Minerals and Chemical Corp. and came up with a similar conclusion (Schumacher, 1983). Bailey and Robin (1983) also talked about the importance of sand system control in foundries. In their article, they concluded that testing for quality of casting needed to deal with the testing of sand properties and processes to ensure that quality product is being made. The major tests in both green, as well as chemically bonded sands were covered (Bailey, 1983).
In a paper, titled new concepts of green sand technology, Boenish and Dietmar
(1988) listed their observations of changing sand properties and molding problems caused by an increase in core sand inflow, condensate accumulation, moisture, faster sand
36 recycling, reduced preparation times, and higher compaction and proposed a sand control practice addressing those problems by assessing production risks (Boenisch, 1988).
Sand/Metal Ratio
Heine (1977) studied the effects of sand/metal ratio and moisture content in the cooling of green sand. In this study, sand under different initial moisture content and sand-to-metal ratio was used. Rapid cooling of shakeout sand due to moisture evaporation is assumed to occur at 140°F (60°C). The study concluded that return sand temperature, residual moisture content, and sand/metal ratio are related to initial sand temperature. Heat transfer to the sand is adiabatic (Heine, 1977). For the given initial temperature, higher sand to metal ratios lower the return sand temperature and raise the residual moisture.
Chemical Properties
Physical characteristics of the sand mixture are governed by the chemical properties of the sand and additives. The pH test is a rapid method of studying the effects of the chemical constituents of ingredients on sand properties. The pH test measures the available exchangeable H2 or similar ions. Anions and cations present in the individual ingredient influences physical properties of a sand mixture based on the ability of the ion to interact. Such as the action of the ion depend whether the ion is an inherent part of the product or is induced during the manufacturing, ratio of the ions presents and particle size of the ingredients (Philips, 1970).
37 Study of the effects of different electrolytes on sodium bentonite was done by
Lawrence (1962) suggested that the effect of a cation is also related to the anion present.
He further illustrated that the same cation produces different strength levels, workability and deformation when sodium bentonite was treated using the same cation with different anions, this is also endorsed by Philips (1970).
Performance of clay bonding is influenced by the acidity or alkalinity of the sand mixture. Zang (1969) has reported the effects of pH on sand properties and resulting casting quality. His work proved that the green sands sand properties will change with the chemical treatment of clay-bonded sand and influence the casting surface finish. The ability of a sand mixture to retain moisture is related to pH. Extreme acidity or alkalinity tends to accelerate moisture losses. Acidity has appeared to be slightly more influential
(Philips, 1970). pH also affects green compression strength. Extreme acidity or alkalinities both lower the green compressive strength (LaFay & Krysiak, 2008).
Alternative Sand System
In an attempt to find an alternative sand system with better properties, Somers (1973) tried various organic materials, which help to reduce substantial portions of temper water in green sand (up to 75%). In addition, cohesive packing characteristics, as well as other molding and casting properties, are improved and are compatible with conventional green molding sands (Somers & Melcher, 1973). In another study, effects of variation in water content, clay fraction and sodium carbonate additions on the synthetic igbokoda clay and silica sand was studied to increase the flowability of the system sand. In this investigation, pure silica sand is characterized and used as a base sand for the igbokoda
38 clay-sand mixture to develop an efficient synthetic molding sand. Additions of Na2CC>3 to the molding sand were examined to study its influence on mechanical properties of the synthetic molding sand. Test results of green compressive strength, dry compressive strength, green and dry shear strengths, collapsibility and toughness did indicate that igbokoda clay poses good characteristics as a binder for synthetic molding sand. In general, addition of Na2C03 gives improved properties to molding sand although it has a tendency to impair collapsibility. (Loto & Adebayo, 1990)
Friability in Green Sand
An AFS paper "Friability of green sands" by Heine and Mcintosh (2001) raised the concern of increasing friability of green sand in recent years. In a study of three main molding systems, annual average friability was raised to 15% till 1998. From rank-order analysis, increase in friability was found related to an increase in the percentage of the methylene blue (MB) and active clay ratio (ACR). In addition, ACR establishes the quality of the bonding medium associated with AFS clay. Lower ACR is accompanied by lower friability. As AFS and MB clays jointly determine the friability level in a sand system, higher value of both MB clay and ACR lead to more friable molding sand. Low values of ACR at given MB clay can produce less friable sand. It was observed that until
1993, AFS and MB clays were balanced and ACR was maintained below 75%.
Consequently, friability remained below 10% (Heine, 2001). Later, to increase the flowability and improve other properties, this proportion was no longer maintained. In addition, concern over introducing different chemicals as well as changing molding parameters for higher productivity dominate the friability issue. From the above
39 discussion, it is inferred that a higher level of active clay is the only option to lower the
friability. However, higher ACR will hurt flowability and productivity as well as increase
the cost. The existing technology is falling short and lacks the confidence to tackle this
conflict. As a conventional way of business tradeoff, friability is less considered and
ignored. This restricts producing thin sections and incurs more friability-related defects.
In a study, Graham et.al (1979) found that friability is inversely related with clay.
This is verified through a similar study done by the author at Western Michigan
University. Friability increases rapidly when the clay is reduced in a given sand system,
which is shown in Figure 10.
Figure 10. Relationship between Friability and Clay
In addition, the role of moisture is also crucial in clay sand interaction for given clay content. Compactibility goes up as moisture increases. Moisture and compactibility have an inverse relationship with friability. Friability will increase rapidly when
40 compactibility is decreased below 40% (Graham, 1979). Figure 11 displays the relationship of friability with compactibility.
Friability Vs. Compactibility
• i 20 30 40 50 60 70 Compactibility (%)
Figure 11. Relationship between Friability and Compactibility
From the literature review, it is now apparent that casting quality is directly related to mold quality, which is to a great extent dependent on sand control. Therefore, sand control is essential to build quality in castings. In sand control, the following parameters are normally considered as input variables (Krysiak, 1994); (Ramrattan, 2008).
• Amount of moisture
• Amount and type of clay or bond
• Amount of new sand addition, and
• Content of carbonaceous material
As mentioned in previous sections, test programs are developed for the control of foundry system sands. These sand control programs are evaluated and applied in foundries for years. As a summary of all studies, moisture and compatibility are
41 established as the key tests for controlling water additions. Green strength, methylene
blue and AFS 25 micron clay provide the important information relating to the bond.
Density, specimen weight, permeability and grain fineness are related to new sand. LOI is
used for quantifying carbonaceous material. Green deformation, dry compressive
strength, splitting strength, friability, cone jolt toughness, wet tensile strength, etc are
considered as optional tests as per the American Foundrymen Society (AFS) sand tests procedure (AFS, 2000). During processing, sand properties will keep changing although the rate might be different depending upon sand type, its composition and operating conditions. For example, green compression strength and compatibility will change rapidly, while LOI tends to change slowly. Further, change in one parameter may affect other green sand properties too (Dietert, 1974). A known working range for each green
sand property is therefore essential. The traditional molding technique has a standard working range for green sand properties. New molding technology, like aeration sand filling, also requires the knowledge of a similar kind of workable range. To establish such standards various sand tests need to be completed.
Various constituents of the sand molding and different sand control approaches are discussed and established that every ingredients of the green sand are equally important and needed to be managed properly to avoid green sands related defects. Some of the casting defects are presented in the following section.
Casting Defects Due to Moisture
Water is indispensable in green sand for moldability. Sand and dry clay only serves nothing in sand molding. Water hydrolyzes and induces the binding characteristics
42 of the clay. On the other side, water readily vaporizes when pouring molten metal in the mold and generates steam; the same steam penetrates into the molten metal and develops gas defects. Levelink (1973) reviewed moisture related casting defects in detail; water explosion and scabbing are the major two defects, which are shown in Figure 12.
Water Explosion
Water explosion is a major casting defect challenging modern molding lines. This defect appears as a roughness and penetration, which are usually localized, but sometimes may cover the entire casting. Gas inclusion and flashes may also be attributable to explosion defects. It is found that all of these defects are due to the impact of heat transfer between liquid metal and the wet mold wall. The water begins to evaporate explosively as the molten metal approaches. Water vapor penetrates into the metal, displacing and forcing it into the sand pores or the joint of the mold. Sometimes vapor bubbles lodge in the metal and are found later as blowholes in casting. This happens when a quantity of metal penetrates slightly into the pores of the mold. At this situation, steam bubbles are developed on the sand grain. If the metal in the surface pore solidifies quickly, it will block the way-out for the steam bubbles and these bubbles are thereby forced to enter into the metal (Landenberg, & Frank, 1973).
Scabbing
The name scabbing came from the appearance of these types of defects as the scab in human body. A typical scabbing and blow-hole defects are shown in Figure 12. Blow
43 holes are developed due to the steam bubbles on the metal mold interface and forced into the metal as described earlier.
(a) Blow Hole (b) Scab Defect
Figure 12. Casting Defects (Source: Ramrattan, 2008)
Tendency of scabbing increases considerably with increasing mold hardness because the surface layer is more rigid as it expands during heating, thus giving rise to a higher expansion pressure. This augments the risk of fracture in the condensed layer behind it.
Increasing the strength of this layer by raising the active bentonite content reduces the scabbing tendency. A lower expansion pressure in the molding sand can be obtained by reducing the moisture content.
The fact that explosion effects have begun to occur in recent years is closely connected with developments in production methods. On the one hand, higher pouring rates and "uncontrolled" casting with automatic machines have increased the chances of
"pouring shocks". On the other hand, in molding sand, all factors increasing heat conductivity will enhance the tendency to water explosion. Such as higher clay content and the content of coke from coal dust. Water increases both heat conductivity and quantity of steam developed. Therefore, moisture content should be kept as low as
44 possible. Lowering moisture content benefits mold quality by (Somers and Melcher,
1973):
1. Increasing resistance to expansion defects
2. Improving facing and peeling action giving better surface finish
3. Reducing chilling, thus permitting lower pouring temperatures in some cases
4. Lower gas evolution from water as a steam
5. Stabilizing mold wall movement and avoiding any distortions and deformation
6. Better parting characteristics
7. Better filling in deep pockets
8. Easy shakeout of sands bonded with western bentonite.
Although low moisture content generates numerous benefits, it is not possible to reduce the moisture below certain level. In one side, lowering gas evolution by lessening moisture in green sand in association with the lower pouring temperature aids in control of moisture-induced gas defects. In the other side, insufficiently tempered sand due to less moisture, produces a weak mold. A weak mold could not hold the pressure of the molten metal and the mold wall collapses giving the miss run defects as shown in Figure 13.
Figure 13. Casting Defects Due to Weak Mold (Source: Ramrattan, 2008)
45 The ultimate goal of sand control is to make green sand molds that can produce castings with dimensions closer to pattern size, with smoother surfaces and a weight reduction. Reduction of chilling allows gating and risering change to increase yield.
Production yield is the ratio of the weight of the actual castings to the weight of metal pour. Lesser requirements of gating save the weight of the metal to be poured, and near net shape casting minimizes secondary finishing operations (machining, grinding, etc.).
Friability Related Casting Defects
A higher rate of green sand filling is necessary in high-speed production line, which has increased the risk of sand erosion. This problem should be approached via an improvement in the resistance to erosion of the mold surface. Sand grains should be firmly anchored in the mold surface so that they can offer to withstand erosive metal flow. A high content of fine material and the use of a fine grade of sand work favorably
(Level ink et al., 1973). Tendency to keep moisture content of the sand as low as possible for other reasons clearly has adverse effects to erosion susceptibility. A study shows that while attempting to improve other green properties, friability has worsened considerably in later years (Heine and Mcintosh, 2001).
Comments on AFS Standard Tests
It is widely accepted that test data collected from the standard AFS testing protocols that use the 3-ram method do not truly identify the sand problem that causes a specific casting defects. Following is a list of some of the possible reasons for this situation.
46 1. Tests are performed under controlled environment, which is not the case in the
production lines. Shop floor's ambient conditions varies depending upon the
season and the time of the day
2. Mixture ingredients, condition of muller, as well as the degree of mixing influence
the test results
3. Mold quality is only as consistent as the machines and the men, which are used to
produce, most of the tests are manual and incur human error
4. The standard 3-ram test procedure consists a significant variation due to its design
and use of the impact loading for sand compaction
Moreover, AFS 80-D committee, which oversees the sand molding research, also concluded that green property test results are subjected to considerable inherent variation, which originates from procedural and operational error. In addition, poor sensitivity and repeatability of the sand test are the other contributing factors. Some test procedures philosophically lack their creditability. It is fundamentally wrong to predict the dynamic nature of the process parameter with a static test. Further, a test carried out at room temperature cannot detect the changes in the parameters incur due to the elevated metal pouring temperature. To reflect the actual scenario of the molding and better control the sand system, dynamic tests with higher sensitivity are essential.
Cone Jolt Toughness Test
The existing cone jolt test is simple, but lacks the repeatability and accuracy. The basic concept of cone jolt is applying a dynamic load in the sand specimen through a solid cone. The specimen, with the cone on top, is raised and dropped against an anvil.
47 Gravitational force exerted by the cone is the actual applied external force. Raising and dropping is done until the specimen breaks and the total number of jolts before failure is recorded and presented as the toughness number of the sand. Conventionally, 20 or more jolts are required to withstand the vibrations and other impacts caused by abuse in mold handling. Furthermore, this test procedure is time consuming, lacks flexibility and displays only the ultimate strength.
Erosion Test
In an attempt to study the erosion at the mold surface, Levelink (1973) has tried to test the sand erosion by heating the specimen in the furnace at 2552°F for five seconds.
The heated specimen is then rubbed against a wedge five times. The amount of sand rubbed off is determined by weighing, and its weight is a direct measure of the erosion susceptibility. The test equipment proposed for high temperature erosion consists of a round metal wedge under a spring load of 160 g, which is pushed lengthwise over a test piece. The rounded point of the wedge is at right angles to the direction in which the wedge moves. This test was carried out on core sands and was used to measure erosion susceptibility by Level ink et al. (1973). This is a hands-on experiment and no further work is available in the literature.
Until this stage review of literature regarding molding techniques, materials, green properties and relevant test are covered. Procedure of mold making and testing will cover next followed by design of experiment and material analysis.
48 AFS Standard Testing Procedure
1. Prepare green sand to desired compactibility levels (40%, 35%, and 30%)
2. Fill standardized AFS tubes for specimen and strike off
3. Take a calculated amount of green sand to make the two inch AFS standard specimen
4. Squeeze green sand in the specimen tube at 0.965 MPa (140 psi)
5. Eject the specimen from the specimen tube using a stripping post, and
6. Carrying out tests
The above mentioned procedure is to prepare a two inch green sand specimen, which is used in most of the test such as GCS, friability, permeability, mold hardness, etc., whereas different amount of sand is used for compactibility, bulk density and moisture test. In compactibility test, the AFS tubes are filled in full and squeezed, and the compactibility is directly measured on the tube with a compactibility scale. Bulk density is calculated by dividing the weight of the compactibility specimen by the volume of the tube. On the other hand, moisture content is measured by heating alO g loose green sand sample.
Preparation of Green Sand
In foundry, green sand needs to be tempered to a certain compactibility level before building a mold. Target level of compactibility is achieved by controlling water additions. Compactibility goes up with an increase in moisture content for a given clay level (Morgan, 1973); (Wenninger, 1970). In a lab test green sand is tempered to a desired compactibility level and sand properties are tested in as mulled condition. The same sand
49 is used in aeration. The sand is re-tempered to start a new run. Standard AFS tests, which are going to be carried out in this research, are listed below in Table 2.
Table 2. Green Sand Testing Equipment
AFS Test Test Equipment Used Model Percent Compactibility Pneumatic Sand Squeezer DISA/319-A Bulk Density Digital Balance (± 0.01 g) NA Moisture Content Percent Digital Moisture Analyzer LA#39086 Specimen Weight (2*2 inches) Digital Balance (± 0.01 g) NA Permeability Digital Permmeter Simpson 42105 Green Compressive Strength Sand Strength Machine Dietert 490-A Mold Hardness Mold Hardness Tester B Percent Friability Friability Machine Dietert 875
The sequence of molding process in aeration and high-pressure blow is shown in
Figure 14. In high-pressure blow, sand after mulling in send to the hopper and then blown into the mold. During aeration filling, sand is aerated in the hopper before blown into the mold.
[ Mixing ) ;;;£( Filling ( Mulling ) | J} Testing Preparation ( compacting ) High-pressure blow Water Aeratic ==£>-l Filling
Finishing § fl. Testing m. J^epi^tt^, [ Compacting J Aeration
Figure 14. Sand Molding Process Flow
50 Design of Experiments
In literature, various articles are available using statistical tools to study sand systems and green sand properties. Design of experiments is used to conduct the experiments by varying multiple parameters simultaneously. For high-pressure blow system, Chakraborty (1982) has considered clay content, moisture content and mulling time as factors with three levels each (Li, 2003). He adopted the orthogonal array to design the experiment. Similarly, Sarkar (1974) has used Yate's method to design the experiments with three factors namely, moisture, clay, and starch with two levels each
(Sarkar, 1974).
Sand-Clay Interactions
X-ray Diffraction
X-rays are a form of electromagnetic radiation that has high energies and short wavelengths, which is in the order of the atomic spacing for solids (~ °A). When a beam of x-rays impinge on a solid material, a portion of this beam will be scattered in all directions by the electrons associated with each atom or ions that lies within the beam's path. Bragg's law defines the relationship among x-ray wavelength, inter-atomic spacing, and the angle of diffraction for constructive interference (Speakman, 2008).
2d sin 9 = "k Equation 5
Where: d: Specimen's interplanar spacing
6: The angle between the sample and the diffracted beam
51 X.: Wavelength used
Diffractometer is used to determine the angle at which diffraction occurs on a powder specimen. A specimen in the form of a plate is supported at the specimen post so that rotation about the axis is possible. This axis is perpendicular to the plane of the table
as shown in Figure 15. The monochromatic X-ray is generated and guided towards the
specimen through a beam. Intensities of the diffracted beams are detected with a sensor.
The specimen, X-ray source, and counter are all coplanar. The table is mounted on a movable carriage that may be rotated about the center axis; its angular position in terms of 20 is marked on a graduated scale.
Figure 15. X-ray Diffractometer
52 Beam intensity is plotted as a function of 29. High intensity peak results when the Braggs' condition is satisfied. Distance between the two peaks in intensity plot gives the interplanar separation.
Scanning Electron Microscope (SEM)
Scanning electron microscope (SEM) is used to obtain a magnified three- dimensional image of any material surface at the micrometer scale. SEM is used to study the bentonite and sand surface to better define the physical aspects of clay coating. SEM can be useful to study the change in clay and their behavior under aeration. It helps to understand the physical changes in clay visually. Structurally, SEM consists of a heavy- walled viewing chamber in a column assembly that produces and controls the electron beam. Photographs of magnified areas can be evaluated and the influence of water, clay and air upon the physical attributes of coating and bonding can be observed. Sand specimens studied under SEM need to be coated by a sputter coater. Sputter coater is used for coating very thin film of vaporized gold or palladium on sand sample. The metallic film on the surface of the specimen helps to dissipate the charge developed during an experiment from the specimen. Otherwise, non-conductors such as sand and clays tend to develop highly charged surface areas when bombarded by an electron beam and interfere in detecting and photographing surface details (Callister, 2007). A picture of the SEM with image display screen is shown in Figure 16.
53 Figure 16. Scanning Electron Microscope
Universal Micro-tribometer (UMT)
Universal Micro-tribometer is used to study the tribology of materials. Basically, tribology is the study of frictional behavior of the material surface. UMT can measure the wear to an accuracy of 50 nm. Forces in the range of milligrams to kilograms can be measured precisely with a resolution of 0.00003% and very high repeatability. The basic
UMT system consists of control and testing unit. The testing unit is equipped with a carriage stage, lateral positioning stage and 2-D force sensor. The carriage stage is motor driven with an encoder for position feedback. It provides the loading force for pressing the tip against the specimen. Lateral positioning stage mounted to the carriage is used to offset the tip from the center axis. A 2-D force sensor senses the vertical or loading force and the lateral drag or friction force. Loading force sensor is used as feedback for the vertical carriage positioning system to maintain a constant force. Combination of loading
54 and frictional force is used to calculate the coefficient of friction. Force sensors can measure up to 50g (Solutions for Tribology Research). A real time plot of the force/load sensor output is displayed on the screen.
Although different types of tests are possible with this instrument, the scratch test is selected because this test closely resembles the friability test used in foundry sand control. In this experiment, the tip is passed against the specimen surface horizontally with a constant loading force and scratching force is recorded as output. The ratio of loading force and scratching force gives the frictional coefficient. The scratching force is nothing more than the force required breaking the clay bond of sand specimen. Micro- tribometer is shown in Figure 17.
Figure 17. Micro-tribometer Scratch Test
As shown in Figure 17, a specimen is mounted on the table, and the stylish with predetermined vertical load and constant speed is applied. The direction of the motion of the stylish is horizontal. The force diagram during scratching is shown on the right in an extended view.
55 CHAPTER in
OBJECTIVE
In the previous chapter of this dissertation, an introduction to the aeration sand filling technique and the importance of sand control, as well as various parameters affecting the mold quality, were discussed. This chapter addresses the objective and rationale of this dissertation.
Viability of any new technology or technique depends upon the cost, safety and quality benefits it can generate. To be a better alternative, aeration technique should be superior to the existing conventional sand filling technique such as gravity and high- pressure blow. From the earlier studies it was shown that aeration has exceeded the cost and environmental as well as personal safety benefits in comparison to conventional techniques. These benefits would not be meaningful unless this technique met or exceeded mold quality requirements. This dissertation focuses on assessing the mold quality produced by the aeration technique. As mentioned in the literature review section in chapter II, quality of molds produced by filling techniques can be measured by quantifying various green sand properties. To measure the green sand properties, or sand behavior, various sand tests are essential. In the first section of this research, green properties of various sand systems under different techniques were compared with aeration. This differentiated the aeration with other conventional filling techniques.
Once the green tests were conducted, the test result could be used to define an optimal working range for aeration. If aeration remained the same as the gravity and high-
56 pressure blow then the existing working range of these techniques might be equally applicable to aeration. Otherwise, a separate working range of compactibility would be required for aeration.
Most of the standard AFS tests are static in nature, which might not be sufficient to assess the dynamic properties reliably and accurately. Similarly, most of these tests are carried out in room temperature and it was well accepted that these tests could not model the actual situation of elevated temperature of metal pouring, which was critical for mold quality. So, there was a need to develop new sand test procedures, which could incorporate the high temperature conditions reliably. Using standard AFS tests, friability appears as an interesting property, which behaves differently in the fluidized sand of aeration. Cause(s) behind this change need to be studied and understood. The "Thermal
Erosion Tester" was proposed to study the friability behavior at elevated temperature.
Similarly, there was a concern about the reliability and relevance of standard AFS green strength tests, which are static in nature and cannot tell much about the dynamic nature of the loads encountered during the transfer and handling of molds in molding lines. The cone jolt toughness test was used to see the dynamic loading conditions but this test is too primitive and lacks the repeatability and accuracy. There was a need for improvement to make this test more sensitive and reliable.
Study of the material properties using various advanced tools helps to understand the effect of aeration and other filling technique in sand clay relationship. The analysis evaluates the chemical and microscopic composition, as well as crystal structure orientation of the sand and clay particles. These analyses answer the questions about the cause of different behaviors of green sand from different techniques. Considering the aspects of sand tests, to develop the new knowledge base for aeration filling technique
57 regarding its implication in sand-clay interactions and green properties, the objective of this dissertation was determined as follows:
1. Compare green sand properties of aerated sand against conventional gravity fill
and high-pressure blow
2. Optimize green sand properties of aerated sand for better mold quality
3. Investigate toughness of aerated green sand using Dynamic Cone Jolt Test
4. Investigate friability of aerated green sand at elevated temperature using Thermal
Erosion Test
5. Investigate the effects of aeration in sand clay interactions using x-ray diffraction,
SEM and UTM
Sand casting consists of molding, melting, filling and finishing processes. For quality castings all four processes must be carefully monitored and controlled. Molding, which is the first step, is more critical than any other succeeding processes. In addition, sand molding is a very unstable process and hard to control. If not controlled properly during molding, no other option is available in the subsequent steps of avoiding defects.
Thus, sand control is crucial for quality castings. Sand control is achieved through green sand property tests. Various tests' procedures published by AFS were discussed in the literature review section of this dissertation. These properties were affected by the various factors including the filling and molding technology. Aeration molding technique is a new sand molding technology in foundries; its impact on green sand properties and resulting quality of the casting needs to be studied. Green sand mold from the aeration technique and its green sand properties test are performed for the first time, and no previous information is available in the literature. The results from this research are expected to be a reference or a knowledgebase to the foundries using the aeration molding
58 system. The comparison of the aeration with conventional molding technique will decide its future. Determining the performance of a molding technique only by the laboratory test results is challenging because these tests might be misleading in some cases. Moreover, most of the tests are not sufficiently reliable. The true assessment is only completed when a casting is produced by pouring the molten metal into the mold, and the quality of the casting is evaluated. A decision could possibly be made once the casting confirms the green sand properties test results. A test casting trial was conducted to eliminate the ambiguities of the laboratory tests. The last but the best part of this dissertation was to investigate the clay sand interactions in different molding technique. Different kinds of tools were identified and employed to study sand clay behavior.
59 CHAPTER IV
METHODOLOGY
This research was primarily based on laboratory experimentation. Green sand properties were investigated in a controlled environment at the Western Michigan
University (WMU) sand testing lab to meet the objective of comparing and optimizing green properties of the aeration filling technique. Multiple factors were considered and the main effects of each factor were evaluated using the design of experiments and other statistical tools. After finding the relationships between the factors and their impact in the green properties, the optimal working range for aeration could be defined using that relationship and other constraints. In developing and using the dynamic tests, various factors and parameters would be identified, and the requirements and functionality of the test would be specified. The parameters would be selected from the existing practices and guidelines of foundries. The last portion of this objective was related to the material analysis.
The starting point would be to identify the nature of information required to understand the sand-clay interactions with filling techniques. From the literature, it is evident that clay is a plate-like particle, which is very sensitive to moisture, and its orientation, as well as property would vary with a minor change in moisture and other operating conditions. The study of the clay orientation was the first step, which was done with x-ray diffraction and SEM. From the information of this analysis, the interactions and changes of the sand-clay relationship would be explained. Throughout the
60 experiments, general practice of sand control, as mentioned in chapter two of this dissertation was followed, and special precaution was taken to contain the moisture loss by keeping the sand samples in a sealed container. Following were the major steps used to carry out this research:
1. Design of Experiment (DOE) and conducted the experiment
2. Analyzed the effects and compared aeration with the high pressure blow and the
gravity filling technique
3. Studied the cause of lower friability in aeration
4. Developed new sand testing methods
5. Optimized and established the best workable range of green sand properties for
aeration
The DOE approach was applied to plan and prepare the experiment. The development of the DOE helped to simplify the problem and provided a systematic way to carry out the experiment. An impact on test variable was quantified while multiple parameters were varied simultaneously. First of all, a recipe, which was a list of experimental sequences with varying levels of factors for the experiments, was prepared.
Data analysis was done after the experimental runs. After the experimental results, main effects were calculated and an optimal range for all factors was developed.
Design of Experiments
The first phase of this research was focused on studying the green sand properties of aeration and comparing them with the green properties of conventional high pressure and gravity system. Initially, two filling techniques, aeration and gravity were considered.
61 To evaluate filling techniques, five different sands were tried. Lake silica, round grain silica, olivine, ceramic media and chromite were chosen as green sand aggregates. Lake and round grain silica are the primary sands used in foundries. Olivine sand is used in aluminum casting, and is a popular alternative to silica sand. Chromite is the high-density sand used in ferrous castings such as steels. The reason for incorporating chromite in this study was to assess the performance of aeration with heaver sand system. Ceramic media represented the ceramic group. In addition, compactibility was selected as a baseline to study the green properties as per the industries best practice and guidelines from the literature (Bralower, 1989). Water was the operating factor to control the compactibility.
Compactibility was set to three levels: 30%, 35% and 40%. North American foundries, especially in Michigan use the compactibility level from 35% to 40%. Author incorporated the 30% compactibility level to study the green properties at the lower side, and tried to extend the operating range of compactibility. Lower compactibility has many advantages such as higher flowability of the sand; lower compactibility requires low moisture and reduces gas defects etc. In this way, there were three factors: sand type, filling techniques and compactibility. Sand type had five levels. Filling technique and compactibility were two and three levels respectively. Factors and levels of each factor are listed in Table 3.
Table 3. Factor and Level Codes for Design of Experiment
Factors Level Sand Type Compactibility Filling Technique 1 Lake sand 30% Gravity 2 RG 35% Aeration 3 Olivine 40% 4 Chromite Minimum number of runs required for full 5 Ceramic Media factorial design = 5 * 3 * 2 = 30
62 Similar size and grain distribution were used for all sand systems. The amount of clay and its proportion were kept constant throughout the runs. Clay, which was pre- blended, contained 80% southern bentonite and 20% western bentonite chosen as a general industrial practice. Amount of total clay added was 8.0%, which is the amount of clay most of the foundries used. Water was the only factor that was changed to produce the desired compactibility. Room temperature and relative humidity were maintained at
22±1°C and 50+2 percent, respectively. Mixing, mulling and aeration parameters such as mulling time, aeration pressure and time were kept constant. Apart from sand, clay, and water no other additives were introduced to the green sand systems because it is an attempt to develop an environmentally friendly technology avoiding chemicals in the foundry sand system. Environmental and operating conditions are listed in Table 4.
Table 4. Environmental and Operating Conditions
Preparation Aeration Testing Room Environment Sand Grain Size: 60 GFN Pressure: O.lMPa Temperature: 22+l°C Distribution: 4 sieve Time: 2 sec Relative Humidity: 50+2% Clay: 8% Mulling Time: 3 min
Environmental conditions were set to the level of a standard testing lab. The control environment was set to avoid any variations in the test results. Otherwise, green sand properties changes significantly even with a minor change in relative humidity and temperature. In addition, sand samples were kept in a sealed container to avoid any moisture loss during handling and running the experiments.
63 Decision Variables and Data Collection
As mentioned in a previous chapter, mold quality was assessed through the measure of the green sand properties. Various tests procedures were tried to investigate mold quality in the initial study and the following were selected as the most relevant green sand properties (tests) to incorporate all aspects of the mold. Tests were carried out and results were recorded and used for further analysis.
a) Compactibility
b) Moisture content
c) Permeability
d) Green compressive strength
e) Bulk density
f) Mold hardness
g) Friability
After collecting data, the nature of statistical distribution for each data group was studied, and checked if they were fit with the standard normal distributions.
Measure of Performance and Their Estimation
In the green sand molding, moisture and compactibility are used as a fundamental test to monitor the sand system. Moreover, compactibility is treated as a reference to compare the performance of other green sand properties in a mold. In this research, change in compactibility, techniques, sand types, and their interactions were measured in terms of the following green properties.
64 Mathematical models for this experiment and design were as follows:
[1] Permeability
Pijkm=H +Si + Tj + STy + Ck + S Cik + T Cjk + S T Cijk +em(ijk) Equation 6
[2] Green compressive strength
Gijkm=n +S; + Tj + STy + Ck + S Cik + T Cjk + S T Cijk +em(ijk) Equation 7
[3] Mold hardness
Hijkm=u +S; + Tj + STy + Ck + S Cik + T Cjk + S T Cijk +em(ijk) Equation 8
[4] Bulk density
Bijkm=u +Si + Tj + ST;j + Ck + S dk + T Cjk + S T Cijk +Em(ijk) Equation 9
[5] Friability
Fijkm=u +S; + Tj + STy + Ck + S Cik + T Cjk + S T Cijk +£m(ijk) Equation 10
Where, Gykm, Pijkm, Hjjkm, Fjjkm were the respective measured variables (experimental test results), u was a common effects in all observations (true mean of the population from which all the data came from). S; was sand type effects (where i = 1, 2, 3, 4, 5). Tj was filling technique effects (where j =1, 2). Ck was compactibility effects (where k = 1,
2, 3). £m(ijk) was random error in the experiment (where m = 1, 2, 3, 4, 5) and other terms stand for interactions between the main factors S, T and C.
Determination of Minimum Number of Replications
This experiment consists of a long procedure of sand preparation, mulling, aeration, filling and testing. To get a set of data point or for a set of experiment, it takes four to five hours and an overhead was also associated in the experiment. Compactibility
65 was used, as a base line for comparison and to get target compactibility was also difficult due to the stringent operating conditions. To reduce the variability in the results, compactibility percent was targeted to a range of ±1 percent. Due to the time, cost, and complexity constraints, four replications were taken. Thus, total numbers of experimental runs were 120 (30 * 4). Comparison of multiple techniques and selecting the best was the next step of the statistical procedure.
Analyzing the Effects of Aeration and Comparison
Comparison of Multiple Alternative Sand Filling Techniques
This part consists of the following two sections:
A. Comparison of two techniques
B. Selection of the best technique
Before comparing the values, selection criteria needed to be established. For this research, the selection criteria of the objective functions of the given model were as follows.
• Improvement of permeability (higher was better)
• Improvement in strength (higher was better)
• Mold hardness (higher was better)
• Improvement of friability (lower was better)
66 Test of hypothesis for comparison was as follows:
Null hypothesis: Ho: (iai =Mgi Equation 11
(Equal means: aeration and gravity)
Alternate hypothesis: Hi: ua; ^ |igi Equation 12
(Mean effects were not equal)
Where subscripts i = 1, 2, 3 and 4; green properties listed above, and a = Aeration, g = Gravity
This was a case of multiple system design, so Tukey approach of multiple comparisons was used. For a specific green property, pair-wise difference of the technique is given by:
Dr = (Ya-Yg), Equation 13
Where Ya and Yg are the respective test results in aeration and gravity and r is number of replications.
— 1 R Sample mean: D=—^Dr Equation 14
1 * 2 2 2 Sample variance: S D = (^D - RD ) Equation 15
5 Standard error: S.E (D )=—M= Equation 16 JR
Ya —Y Test statistic: T = J. Equation 17 SDjR
67 In the multiple comparisons, each green sand property was compared individually.
Variance and the means of test results determine the best techniques to be selected. The desirable criterion was as follows:
1. Lower friability
2. Higher permeability
3. Higher green compressive strength
4. Higher bulk density
5. Higher mold hardness
Optimizing and Establishing Workable Range
From the test data, impact of compactibility on green sand properties was accounted and the relationship was derived using regression as follows:
y = /(•*) Equation 18
Where, y was green properties and x was the independent variables such as sand types, compactibility and filling techniques. For aeration, the independent variables were sand types and compactibility. Most of the foundries select sand type depending upon the design and type of metal they pour. From the filling technique's perspective, question regarding the sand type was whether the aeration can fill it or not. Once a sand type was successfully filled, the criteria for sand type were fulfilled. Finally, compactibility was the only factor that governs the green properties as well as the best technique.
68 Experimental Procedures and Setups
For standard AFS tests the following procedure was followed with five major steps:
1. The green sand was tempered to the desired compactibility level
2. Green sand was transferred into sand hopper of high-pressure blow system and
aeration chamber of aeration system
3. Pressure in the aeration and high-pressure blow were set to O.lMPa and 0.3Mpa
respectively, and the filling time was 2 seconds
4. Fill molds or tubes
5. Carry out AFS green sand tests
As mentioned before, two types of silica and three types of specialty green sand systems were tempered for this study. Compactibility was monitored continuously. Water additions were then raised or lowered accordingly on the batch of sand to produce the target compactibility. Sand was transferred from muller and sent to a filling system only after attaining the target compactibility. Sand was recycled after the experiment for the next run without pouring metal into the mold. Compactibility of the green sand after filling was recorded for comparison.
Equipments used in this research were the Simpson sand muller, digital balance with 0.0 lg sensitivity, sand squeezer, rammer, AFS standard specimen tube, compactibility scale, aeration system, and high-pressure blow equipment. For green sand properties test, AFS standard procedure was followed as mentioned in chapter two in this dissertation. Specimens for x-ray were prepared by squeezing the sand into a rectangular aluminum holder using a squeezer with a pressure of 0.965 MPa (140psi).
69 High-pressure Blow Setup
In high-pressure blow system, AFS tube was placed vertically under the sand hopper and the green sand was blown into the tube by the blast air, which was regulated to a pressure of 0.3MPa. Similar types of vents, which were used in aeration, were mounted at the bottom of the tube. Schematic diagram of high-pressure blow set up is shown in Figure 18.
Air Supply (0.3 MP a)
1
Hopper
AFS Tube
Figure 18. Schematic of High-pressure Blow System
Experimental Setup for Aeration Sand Filling
Aeration equipment built by Sintokogio, Ltd., Japan, was used for aeration filling.
Aeration chamber, flask, air supply and regulating unit and control panel were the main components of the aeration system. The fluidizing chamber consisted with a micro- porous filter lining. Air supply ports were designed in various locations of the chamber to
70 provide a uniform aeration of the green sand. A rectangular nozzle was mounted on the bottom of the chamber connecting a flask as shown in Figure 19.
Aeration Filter
Air inlet DZ^> Uj
Pressure Sensor
Nozzle
Vents m Tubes
Figure 19. Schematic of Aeration Sand Filling System
Venting facility was provided from the different locations of the flask, which provided the air passage during filling and facilitates the process. Aeration system also consists of control panel and data collection system, which was connected with the computer. The system was built with the configuration suitable to build the mold of size
260 mm in length 300 mm in width and 500 mm in height.
71 Three half-section horizontal sleeves each of diameter of 60 mm and 120 mm long were mounted in the experimental matchplate. Further, three AFS standard 315-19 specimen tubes were located in the sidewall of the flask horizontally behind the sleeves as shown in Figure 20. Vent holes were attached at the bottom end of each sleeve and tube to facilitate the directional flow of the air during filling.
(a) AFS Specimen Tubes (b) Half-section Sleeve on Acrylic Cover
Figure 20. Experimental Matchplate with Half-section Sleeves and AFS Tubes
In this system, sand was fluidized by air passing through the filter at aeration chamber. Such fluidized sand was then transferred into the flask through the nozzle slowly and steadily with low-pressure air (O.lMPa). The slow and steady flow of green sand filled the flask bottom-up, which started filling the flask from its bottom all the way to its top, filling the tubes and sleeves continuously and uniformly. After filling the flask the tubes full of green sand were ejected and prepared for AFS test specimens.
72 Pressure sensors were mounted at the different parts of the aeration chamber and the air supply tanks. Air tank pressure sensor helped to regulate the air supply whereas the others read the aeration pressure and record, which could be useful to study and analyze the aeration process. Sequence of aeration and sand transfer could be controlled manually as well as automatically. Air inlet manifold with valves were attached to the aeration module, which supplied the controlled amount of air for a predetermined time period for green sand aeration and transfer. Control panel had a touch screen display, which helped to set the aeration time and pressure, and display the pressure curves. A typical aeration pressure curve is shown in Figure 21.
Figure 21. Aeration Sand Filling Pressure Curve
As shown in Figure 21, peak pressure level was approximately 0.06 MPa and aeration time was two seconds, the aeration process was started at 0.5 seconds and was completed at 2.5 seconds. When the sand flow was began from the chamber to the flask after aeration, the pressure on the aeration chamber dropped.
73 Developing New Green Sand Testing Methods
Conceptualization, design, build and operations were the four stages used to develop the new testing techniques. In the conceptualization phase, the necessity of the test and its functionality was considered. Depending upon the design, the test equipment was built as a part of a various design projects in metal casting lab at WMU (2008). The protocol for the test procedure was developed based upon the nature of the test data required.
Advance Cone Jolt Test
Advance cone jolt consisted of a base plate, cone, Linear Variable Differential
Transformer (LVDT), counter, solenoid and a PC with Lab VIEW program. Specimen was kept on the base plate, which was raised and dropped by a cam (or solenoid) during the experiment. The cone was placed on the top of the specimen and was acted as a load with its dead weight. LVDT was used to measure the penetration of the cone into the specimen. Figure 22(a) shows the schematic diagram of improved cone jolt toughness test equipment.
The numbers of jolts in the experiment were counted with an electronic counter and recorded, and toughness of the specimen was expressed as the number of jolts, which the specimen did withstand until its failure. In addition to the number of jolts, cone tip movement was also captured and plotted against time, which provided a data to measure of the energy absorbed by the specimen before failure.
74 LVDT
Cone Jolt Rot
c Base CD 0 s-s js-E. -0.1 8- o -0.2 0.5 1 1.5 Time (sec) Counter
a) Advance Cone- Jolt b) Cone Penetration curve
Figure 22. Advance Cone Jolt
Thermal Erosion Tester
During pouring, pressure and velocity of the molten metal plays a large role to erode the sand from the mold surface. The frictional force is the main cause responsible to erode the sand after the heat and temperature of the liquid metal flow. The clay, which was burnt due to the high heat, lost its bonding capability and the mold surface became weak. The weak mold surface could not sustain the friction enough, and it won't take much effort to wear off by a metal flow. Frictional force is dependent upon the pressure and velocity of the flow. In metal filling, pressure is expressed as the head height and the velocity is determined by the flow regime. Usually, metal caster try not to exceed the laminar flow (Re < 10), with approximately 0.5 m/sec velocity (Ramrattan, 2008). The test equipment was designed in such as way that the pressure head and velocity of the
75 rotation of the hot element could be adjusted so that it would reflect the actual scenario of the metal flow. Schematic diagram of this equipment is shown in Figure 23.
Figure 23. Thermal Erosion Tester
As shown in Figure 23, the thermal erosion test equipment consisted of a taper cylindrical hot surface, thermocouple, motor, base plate and a computer with Lab VIEW program. A loose sand collection chute and digital scale was attached to read the sand erosion in real-time. Hot surface, which was heated through inner filament, was designed to mimic the high temperature situation of metal pouring. There were small axial grooves on the cylinder surface, which provided a way to release eroded sand from the specimen during the experiment. A motor operated the hot surface, which could be rotated and lifted simultaneously. This design was developed to reflect the actual situation of metal flow and pressure head of metal pouring. The temperature was controlled by
76 thermocouple. The standard AFS specimen (2 inch * 2 inch) with a tapered hole inside was used in this test. The size of the hole could be changed to reflect the change in sand to metal ratio. In this test protocol, green properties of the sand were tested before and after heating. During the experiment the test specimen was placed in contact with the moving hot cylinder for 5 sec. Weight of the lost sand was collected and recorded in real time through a data collection system. Amount of sand loss was expressed as the percent erosion of the sand system or the friability at high temperature.
X-ray Diffraction Setup
The X-ray diffraction experiment consisted of X-ray machine, power regulator and PC with XRD program. Specimens for X-ray diffraction were prepared by pressing sand into a pocket of a rectangular holder of size 20mm * 15mm * 4mm. Size of the pocket was 10mm * 10mm * 3mm as shown in Figure 24. Sand was compacted well into the pocket with 140 psi squeeze pressure to avoid loose sands. This specimen was mounted in the sample post of the X-ray diffractometer to carry out the experiment.
/__
Figure 24. Specimen Holder for X-ray Diffraction and SEM
77 Scanning Electron Microscope (SEM) Setup
The rectangular specimen holder used in X-ray diffraction was also used for SEM.
After the sand sample was compacted into the specimen holder, gold-palladium plasma coating was placed on the top surface of the specimen using a sputter coating. In SEM, specimen holder was mounted on a sample post and glued with tape to prevent any movements during the experiment.
Universal Micro-tribometer (UMT) Setup
The schematic of the UMT experimental setup is shown in Figure 25. A spherical diamond tip was used for scratching with the linear speed of 0.4 um/s. The vertical load
(Fz) was applied to the sample by the carriage. This force was kept constant to 5gm using a close loop feedback mechanism. Friction force (Fx), normal load (Fz), electric contact resistance (ECR) and acoustic emission (AE) were measured and recorded at a total sampling rate of 20 kHz.
Although scratch force was only considered in this research, other functions such as wear depth and digital camera were readily available in this equipment. The following procedure was followed to conduct the UMT scratch test:
• Set the load and length of scratch
• Bring the tip in contact with the sample
• Run the experiment and collect data
78 Figure 25. Close-up View of Specimen Setup in UTM
After performing a series of trial experiments, considering precision, time and nature of material and its bonding strength the optimal level of velocity and length of scratch were selected to be 0.4 um/s and 4 mm, respectively. Total time taken for the scratch was 20 minutes. Friction force (Fx), Normal force (Fz), Electric Contact
Resistance (ECR), Acoustic Emission (AE) were measured and coefficient of friction
(COF) was calculated. Carriage position (Zl) was also recorded to determine wear depth.
In this test, a micro-tip moving slowly against the sample progressively removed the materials and created a scratch.
79 CHAPTER V
RESULTS AND DISCUSSION
From the experimentation it was observed that each of the techniques have their own unique benefits. Gravity filling (as mulled) is a manual and simple method with low cost.
High-pressure blow has a higher productivity rate than the gravity filling technique with the use of machinery and automation. Aeration has its niche on mold quality along with higher productivity, environmental benefit and lower noise level. Some of the observations in the aeration sand filling technique were:
• Complete sand filling into the sleeves and tubes
• Uniformly dense filling
• Higher flowability and smooth flow of sand
• Minimal bridge-forming phenomenon during filling
• Use of low pressure air as well as less air consumption
• Lower noise level
• Compact design and space saving
• State of the art control and data collection system
• Less or no sand spillage
As shown in chapter IV of this dissertation, three AFS (American Foundrymen
Society) standard specimen tubes were mounted horizontally in the mold flask and filled using aeration filling technique. Tubes were positioned at three different locations to
80 observe the density distribution within the flask. All tubes were filled to capacity with green sand with 0.1 MPa air pressure. Aeration enhanced the flowability of the green sand, and the subsequent low-pressure air flown slowly and steadily drove the sand smoothly into the mold. The vents at the ends of the tubes created a directional flow into the tubes. Once filled, tubes were taken to test the green sand properties. Pressure, duration, and sequence of aeration sand filling were controlled with a touch screen control panel, and the pressure and time data were collected with a data acquisition system. The whisking sound of air passing through the vents during sand filling in aeration was not close in any means to the blasting sound of high-pressure blow system.
This chapter is divided into six sections to present the results of the different stages.
In the first section, test results of green sand properties of the molds filled in aeration and as-mulled gravity are presented. In reference to the green sand properties, aeration was compared with gravity filling technique. Five different types of sand and three different levels of compactibility were investigated. In the initial study, aeration filling technique was appeared as a better molding technique having additional benefits over gravity filling technique. Later, aeration was compared with high-pressure blow as well as gravity filling technique, and the results are presented in the second section of this chapter. In the third section, relationship between compactibility and other green sand properties were investigated and optimal compactibility range for aeration is presented. Cause of lower friability in aeration was investigated using X-ray diffraction, Scanning Electron
Microscope, and the findings are presented in section four. In section five, investigation of new green sand testing procedures and their relevance is presented. Finally, a test casting was designed and used to evaluate the performance of the molds built using aeration and as mulled gravity filling. The wedge surface of the test castings produced in
81 different molds was evaluated and compared. The design and result of the test casting, which validated the findings of the earlier sections is presented in the sixth section of this chapter.
Results of Green Sand Test
As described in the literature review chapter of this dissertation, testing of various green sand properties controls sand system in foundries. Compactibility, a measure of reduction in volume of the green sand during compaction, is recognized as a reference green sand property to evaluate other green sand properties. The relationship between compactibility and other green sand properties of various sand systems and environments is readily available in literature for conventional molding. Although all sand systems do not have exactly the same relationship, the general trends are similar. Various parameters such as sand type, grain size and distribution, clay content, temperature and relative humidity affect this relationship. Every foundry has established its own green sand properties relationship unique to their sand system. Normally, foundries are categorized according to the type of castings they produce, and the type of sands they use. For example, iron foundries usually use silica sand whereas aluminum foundries use olivine sand. Foundries prefer to operate with one sand type keeping the same grain size and distribution, clay content, and the other operating conditions; moisture addition is the only parameter they change to maintain the sand system at the target compactibility level.
This simplifies and facilitates the sand system control, which is almost impossible, otherwise. The same approach was followed in this research. As different sand systems were under investigation, it will be beneficial to understand the general trends of the
82 relationship before evaluating the green sand properties of each sand system. This helps
to narrow down and focus the investigation on a particularly relevant area. The data
collection sheet and the initial results of the relevant green sand properties are listed in
Appendix A, and the summary is discussed in the following paragraphs.
Green sand properties of the olivine sand were evaluated at different compactibility levels to map the relationships. Olivine sand with 60 GFN, four-sieve grain distribution and 8% clay was used in this stage of the study. Compactibility was controlled by moisture additions. Change in compactibility with water addition was evaluated by the AFS standard moisture content and compactibility test, and the relationship is displayed in Figure 26. Moisture content is on the horizontal axis and compactibility is on the vertical axis of the graph.
60 -r
50 -
>40 -- 15 ~30 - m
u si. 10 -
0 - 1 1.5 2 2.5 3 Moisture Content (%)
Figure 26. Relationship between Moisture and Compactibility
83 As shown in Figure 26, compactibility increases significantly from 10% to 60%
with a minute increase in moisture content. In the given sand system, an approximately
1.5% increase in moisture content induced a 50% increase in the compactibility levels.
Normally, a 0.1% change in moisture content induced approximately 3% change in
compactibility. The least count of moisture content available in the moisture test equipment was 0.1%. This suggested that to study the green sand at different moisture level, it is necessary to vary compactibility at least by 3%. An increase of 5% compactibility levels was desirable to ensure the change of at least 0.1% in moisture content. Next, green sand properties were evaluated at different compactibility levels. The test results are plotted as shown in Figure 27.
Figure 27. Relationship between Compactibility and Green Sand Properties
84 As shown in Figure 27, compactibility is plotted on the horizontal axis, and other green sand properties - bulk density, permeability, green compressive strength (GCS) and friability- are on the vertical axis. Compactibility was increased from 10% to 60%.
Permeability number had a positive linear relationship with compactibility, and showed a significant improvement at higher compactibility levels. Although permeability appeared more sensitive to compactibility than other green sand properties, it has no practical significance. The higher number was due to the scale of the measurement. For example, an increase in permeability number from 50 to 100 appears considerable numerically but this might not be a significant with respect to the range of permeability number available in the sand molding, which usually varies from 40 to 400, a broad range in comparison to the other green sand properties. For example, friability percent value appears usually in the range of 1 - 40, GCS is in the range of 10-50 psi, and bulk density normally lies in the range of 50-250 lbs/ft3 depending upon the sand types. Bulk density has a negative nearly linear relationship with compactibility, and was varied from 40 - 90 lbs/ft3. Green compressive strength (GCS) increases with compactibility to about 25-30% compactibility and then decreases. Friability, on the other hand, increases significantly with the decrease in compactibility. The rate of decrease is higher below a compactibility level of 35%.
Predicting the green sand properties of a specific sand system directly from the other green sand system is not appropriate; sometimes the estimation might be detrimental. However, such information can be helpful for the general understanding. As shown in Figure 27, permeability was increasing with compactibility whereas friability and bulk density was decreasing. This conflicting relationship forbids the use of any extremes compactibility levels. Lower extreme of one variable leads to the higher
85 extreme of other variable. Lower extreme in permeability is as bad as higher extreme
value in friability. Thus, a middle range of 30-40% compactibility level was selected to
further investigate other sand systems. This range also covers the existing 35-40%
compactibility levels used in the conventional sand molding practices.
After setting up the operating parameters, sand filling using different techniques
was commenced. AFS green sand test were conducted after sand filling and the test
results were recorded. Sand type, filling technique and compactibility were the input
variables or treatments. Permeability, green compressive strength, mold hardness, bulk
density, and friability were the outputs or control variables. Five different types of sand
were used in this research namely: ceramic media, chromite, lake, olivine, and round
grain (RG). By the nature of occurrence and composition, lake and RG are the silica
sands, and others were categorized as specialty sands. Two sand filling techniques were
under investigation: aeration and gravity. Compactibility was the major controlling parameter, which was set into three levels: 30%, 35%, and 40%. Summary of the green
sand property test results and statistical analysis are included in the following sections.
Detailed test results are listed in Appendix C.
Permeability
Permeability is the measure of venting characteristics of the sand mold. As mentioned in chapter n, Permmeter was used to measure the permeability value and expressed the results as a number (#). A higher permeability number is good for better casting quality, which facilitate the gas flow out of the mold towards the atmosphere and prevent from trapping into the metal. From the data available in literature, olivine was the least and
86 chromite was the most permeable sand. Descriptive statistics of permeability test results is displayed in Table 5. The three columns on the left are factors. Five different types of sands (ceramic media, chromite, lake, olivine and round grain (RG)) used in this research are presented in the first column. Two sand filling techniques under investigation
(aeration and gravity) are listed in second column. Levels (30%, 35%, and 40%) of compatibility are listed in third column. The fourth column is the average permeability number of the respective combination followed by the standard deviation in the fifth column. The number of replications of each data point was four, and is presented in the last column. The mean of the average compactibility is also displayed in the table as a total. For the total standard deviation, pool variance was used.
Table 5. Descriptive Statistics of Permeability
Sand Technique Compactibility Mean (#) Std. Deviation N
Ceramic Aeration 3D ??fi 7fi ?9Q 4 Media 35 237.00 .82 4 40 248.50 5.45 4 Total 237.42 3.62 12 Gravity 30 225.25 2.75 4 35 244.50 3.00 4 40 267.00 2.45 4 Total 245.58 2.74 12 Total 30 226.00 2.78 8 35 240.75 4.50 8 40 257.75 10.63 8 Total 241.50 6.86 24 Chromite Aeration 30 354.00 6.48 4 35 370.50 1.29 4 40 383.75 5.62 4 Total 369.42 5.01 12 Gravity 30 310.75 4.27 4 35 327.00 4.16 4 40 343.75 4.79 4 Total 327.17 4.42 12 Total 30 332.38 23.67 8 35 348.75 23.43 8 40 363.75 21.92 8 Total .?4R ?Q ?3n? 24
87 Table 5 - Continued
Sand Technique Compactibility Mean (#) Std. N Lake Aeration sn 9?9 Fin 3 51 A 35 223.75 2.22 4 40 227.75 5.80 4 Total 224.67 3.59 12 Gravity 30 227.75 1.26 4 35 232.75 .96 4 40 260.50 1.29 4 Total 240.33 1.18 12 Total 30 225.13 3.72 8 35 228.25 5.06 8 40 244.13 17.93 8 Total 232.50 10.97 24 Olivine Aeration 30 69.00 4.76 4 35 80.00 3.16 4 40 87.50 1.73 4 Total 78.83 3.45 12 Gravity 30 53.50 1.00 4 35 74.25 2.22 4 40 78.50 1.29 4 Total 68.75 1.59 12 Total 30 61.25 8.88 8 35 77.13 3.98 8 40 83.00 5.01 8 Total 73.79 6.32 24 RG Aeration 30 184.50 3.70 4 35 193.50 3.11 4 40 194.00 1.41 4 Total 190.67 2.91 12 Gravity 30 176.50 1.29 4 35 191.75 1.50 4 40 201.50 1.29 4 Total 189.92 1.36 12 Total 30 180.50 4.99 8 35 192.63 2.45 8 40 197.75 4.20 8 Total 190.29 4.02 24 Total Aeration 30 211.35 93.77 20 35 220.95 95.44 20 40 228.30 98.03 20 Total 220.20 95.76 60 Gravity 30 198.75 86.70 20 35 214.05 84.73 20 40 230.25 90.64 20 Total 214.35 87.39 60
As shown in Table 5, average permeability of ceramic media varied from 226.75 to 248.5 in aeration and 225.25 to 267.0 in gravity. It increased from 226.0 to 257.75
88 when compactibility rose from 30% to 40%. Total standard deviation for aeration and gravity were 3.62 and 2.74, respectively.
Chromite sand appeared more permeable. Average permeability numbers were in the range of 354.0 to 369.42 in aeration, and 310.75 to 343.75 in gravity. When compactibility increased from 30% to 40%, average permeability was also increased from
332.38 to 363.75. Total standard deviations were 5.01 and 4.42 in aeration and gravity, respectively. Total average permeability in aeration was 369.42, whereas the same measure was 327.17 in gravity.
Average permeability of lake sand appeared between 222.5 and 227.75 in aeration, and 227.75 and 260.5 in gravity. Total standard deviation in aeration and gravity were 3.59 and 1.18, respectively. Total average permeability in aeration was 224.67, whereas the same measure was 240.33 in gravity. Total average permeability number increased from 225.13 to 244.13 as compactibility moved up from 30% to 40%.
Olivine appeared to be the less permeable sand system; the average permeability number for this system was below 100, and varied from 69.0 to 87.5 in aeration and 53.5 to 78.5 in gravity. Total standard deviation was 3.45 and 11.5 in aeration and gravity, respectively. Total average permeability in aeration was 78.83, whereas the same measure was 68.75 in gravity. Total average permeability number increased from 61.25 to 83 as compactibility increased from 30% to 40%.
In RG sand system, average permeability number varied between 184.5 and 194.0 in aeration, and 176.5 to 201.5 in gravity. Aeration appeared to have lesser variations than gravity. Total standard deviation was 2.91 and 1.36 in aeration and gravity, respectively.
Total average permeability in aeration was 190.29 whereas the same measure was 189.92 in gravity. From this data set permeability appeared to increase with compactibility.
89 When compactibility was increased from 30% to 40%, total average permeability number increased from 180.5 to 197.75. Dot plot as shown in Figure 28, clearly displayed the location of various sands in the permeability scale.
Diotplo t of Permeability Aeration e RG A Olivine • • • Lake 0 • © • • Chromite O •• • Ceramic Media A O ••• AA O ••• • AAA O • ••• • AAA OOO •••• AAA OGO • ••• Gravity
A + + + A + A • • A OOO • •• A A OOO • • A AA OOO • •• A •••••• T -^-l _, aa$. •••••• i i i 50 100 150 200 250 300 350 400 Permeabflity(#)
Figure 28. Dotplot of Permeability
Figure 28 showed the permeability of different sands in aeration and gravity in two different panes of the same graph. Aeration data are displayed at the top and gravity data at the bottom pane. Olivine and chromite appeared in the lowest and highest extremes, respectively. Permeability values of chromites were relatively higher in aeration to that of gravity. Although distinctive features appeared in different sand system, technique and compactibility, impact of individual factor on permeability was not clear.
To statistically analyze the impact of these factors and their interactions, ANOVA was employed. In the initial ANOVA of permeability, three way interactions among the
90 factors appeared, and are listed in appendix C. Upon examining the sum of squares (SS) of each factors and interactions, the three-way interaction had a very small SS in comparison to the SS of main effects and other interactions. Thus the three-way interactions did not appear to have any practical significance and were removed from consideration. SS of the three way interactions were then accumulated into the error's SS.
The ANOVA with mean effects of factors and two-way interactions is shown in Table 6.
Table 6. ANOVA: Permeability versus Sand, Technique, Compactibility
Factor Type Levels Values Sand fixed 5 Ceramic Media, Choromite, Lake, Olivine, RG Filling Technique fixed 2 Aeration, Gravity Compactibility (%) fixed 3 30, 35, 40 Analysis of Variance for Permeability Source DF SS MS F P Sand 4 943190 235798 14935,.4 7 0,.00 0 Filling Technique 1 1027 1027 65..0 3 0,.00 0 Compactibility (%) 2 11740 5870 371..8 1 0,.00 0 Sand*Filling Technique 4 12170 3042 192..7 1 0..00 0 Sand*Compactibility (%) 8 1181 148 9..3 5 0..00 0 Filling Technique*Compactibility (%) 2 1075 538 34,.0 5 0..00 0 Error 98 1547 16 Total 119 971930 S = 3.97338 R-Sq = 99.84% R-Sq(adj) = 99.81%
As shown in Table 6, ANOVA consists of the sum of squares of the factors and interactions, degree of freedom, F-test statistics and p-value. P-value (p = 0.0) for the two-way interactions was less than critical-value (a = 0.1) for 90% confidence levels.
This suggested the presence of interactions between the factors: sand, technique and compactibility. Not the factors but their interactions were contributing. If higher order interactions exist, interpretation of the lower order main effects is not recommended
(Hicks & Turner, 1999). Thus, the main effects of the individual factors were not chosen to interpret. Other methods available were either looking into the ANOVA and analyzing main effects from the table for sands separately or perform the Post-hoc analysis to
91 evaluate the main effects of the combination. Both of the methods were explored and evaluated the respective main effects. ANOVA for individual sand is shown in Table 7 followed by post-hoc analysis.
Table 7. ANOVA of Individual Sand: Permeability versus Technique, Compactibility
Factor Type Levels Values Technique fixed 2 Aeration, Gravity Compactibility fixed 3 30, 35, 40 Analysis of Variance for Permeability: Lake Source DF SS MS F P Technique 1 1472.67 1472.67 160.65 0.000 Compactibility 2 1660.75 830.38 90.59 0.000 Technique*Compactibility 2 889.58 444.79 48.52 0.000 Error 18 165.00 9.17 Total 23 4188.00 S = 3.02765 R-Sq = 96.06% R-Sq(adj) = 94.97%
Analysis of Variance for Permeability: RG Source DF SS MS Technique 1 3.38 3.38 0.65 0.429 Compactibility 2 1255.58 627.79 121.84 0.000 Technique*Compactibility 2 243.25 121.63 23.60 0.000 Error 18 92.75 5.15 Total 23 1594.96 S = 2.26997 R-Sq = 94.18% R-Sq(adj) = 92.57
Analysis of Variance for Permeability: Olivine Source DF SS MS F P Technique 1 610.04 610.04 84.63 0.000 Compactibility 2 2025.58 1012.79 140.50 0.000 Technique*Compactibility 2 98.58 49.29 6.84 0.006 Error 18 129.75 7.21 Total 23 2863.96 S = 2.68483 R-Sq = 95.47% R-Sq(adj) = 94.21%
Analysis of Variance for Permeability: Ceramic Media Source DF SS MS F P Technique 1 400.17 400.17 38.83 0.000 Compactibility 2 4039.00 2019.50 195.96 0.000 Technique*Compactibility 2 401.33 200.67 19.47 0.000 Error 18 185.50 10.31 Total 23 5026.00 S = 3.21023 R-Sq = 96.31% R-Sq(adj) = 95.28%
Analysis of Variance for Permeability: Chromite Source DF SS MS F P Technique 1 10710.4 10710.4 480..4 7 0..00 0 Compactibility 2 3940.1 1970.0 88,.3 8 0..00 0 Technique*Compactibility 2 15.2 7.6 0,.3 4 0..71 5 Error 18 401.3 22.3 Total 23 15067.0 S = 4.72141 R-Sq = 97.34% R-Sq(adj) = 96.60%
92 As shown in individual ANOVA of sand in Table 7, two-way interactions between the techniques and compactibility existed in all sand system except chromite. In the chromite sand, compactibility levels as well as techniques were significant. The main effects of aeration in permeability were different than that of gravity. Similarly, the main effects of compactibility level were significant. Permeability at 30% was significantly different than that of 35% and 40%. In other sands this might not be the case as there were the interactions among the factors. The main effects of the combinations of the factors might be different but not that of the individual factor. Similar observation was also made in permeability versus compactibility plot as shown in Figure 27.
Figure 29. Permeability of Different Sands, Techniques and Compactibility Level
As shown in Figure 29, although all sand types had the rising trend with the compactibility in both the filling techniques, they were not parallel to each other. In this
93 graph, for given sand - olivine, lake or any - slope of the line was not the same in both techniques, which displayed the presence of interactions visually.
For post-hoc analysis, two different techniques were used: Student-Newman-
Keuls and Duncan. Logic of using two different approaches was to compare the homogeneous subsets from the two tests, which facilitate in decision-making. Student-
Newman-Keuls test result with homogeneous subsets is shown in Table 8. Duncan test result is listed in appendix D. All post-hoc analysis was done using SPSS software.
In this experiment, thirty combinations of the factors were possible, which are listed in the left column in Table 8. First and second letters in the combination name represents sand type and technique, respectively, and the numeral at the end is percent compactibility level. Letters were assigned as followed: L = Lake sand, R = Round Grain,
O = Olivine, M = Ceramic Media, C = Chromite, A = Aeration, G = Gravity. Numbers
30, 35 and 40 were for 30%, 35% and 40%.
In post hoc procedure, data points are grouped together as homogeneous subsets if they are not significant. Data that belongs to the different subsets are statistically significant. Subsets were grouped into columns. Combinations were displayed in a left column and their respective values at right. The table displayed the combinations, their locations and relationship with other combinations, which facilitate the comparison of the different combinations. These subsets were listed in the descending order vertically. Most of the subsets, except few at the middle, possessed one data point. This predicted a significant difference among the combinations, and suggested a wide range of permeability available. Mean square error of this analysis was shown at the bottom of the table.
94 Table 8. Student-Newman-Keuls: Permeability
Si ih Duncan test also the same homogeneous subsets were obtained. From this analysis, permeability appeared more sensitive to sands than the molding techniques. In other words, sand type was the critical factor to affect the permeability although it has some contributions from the interactions. In addition, permeability goes up with compactibility although the rate of change was small, which in fact followed the conventional trend in green sand molding (Graham, 1979). Green Compressive Strength (GCS) Green compressive strength of a mold measures the ability to withstand the compressive load before pouring the molten metal. Universal compressive strength tester was used to carry out this test. In the test procedure, compressive load was applied vertically and the ultimate strength was recorded when the specimen collapsed. GCS was expressed in pounds per square inch. Test results for average compressive strength are listed in Table 9. Data table for GCS was presented in the same format as discussed earlier in the permeability section. Mean and standard deviation for each data set as well as for individual factors were displayed. Test results were also displayed in a dot plot as shown in Figure 30. GCS values were scattered from 16 lbs/in2 to 39 lbs/in2. 96 Table 9. Descriptive Statistics of GCS Data Sand Technique Compactibility Mean (lb/in*) Std. Deviation N 30 31 3.R 1 K4 A Aeration 35 30.02 3.17 4 40 26.26 3.25 4 Ceramic Total 29.21 2.77 12 Media 30 26.27 1.10 4 30.87 4 Gravity 35 1.73 40 27.81 .60 4 Total 28.32 1.23 12 30 33.21 .91 4 Aeration 35 31.09 .37 4 40 26.25 1.90 4 Chromite Total 30.18 1.23 12 30 31.97 .89 4 4 Gravity 35 28.03 1.18 40 25.16 2.22 4 Total 28.38 1.54 12 30 19.13 1.46 4 4 Aeration 35 24.08 1.30 40 23.90 2.75 4 Lake Total 22.37 1.95 12 30 21.21 .23 4 35 24.14 4 Gravity .60 40 24.05 .14 4 Total 23.13 0.38 12 30 31.86 1.55 4 4 Aeration 35 31.69 1.89 40 29.25 .59 4 Total 30.93 1.32 12 30 29.69 .59 4 35 1.43 4 Gravity 35.08 40 31.99 .56 4 Total 32.25 0.95 12 30 21.48 1.07 4 4 Aeration 35 22.85 2.00 40 23.35 .24 4 RP. Total 22.56 1.32 12 30 22.30 .47 4 35 20.56 1.26 4 Gravity 40 22.43 1.85 4 Total 21.76 1.32 12 30 27.40 6.15 20 35 4.20 Aeration 27.95 20 40 25.80 2.85 20 Total 27.05 4.60 60 30 26.29 4.29 20 35 27.73 5.32 20 Total Gravity 40 26.29 3.64 20 Total 26.77 4.47 60 30 26.84 5.26 40 Total 35 27.84 4.73 40 (Sand & 40 26.04 3.23 40 Technique) Total 26.91 4.49 120 97 As shown in Table 9, average GCS of ceramic media varied from 31.35 to 26.02 in aeration and 26.527 to 30.87 in gravity. The highest value was at 35% compactibility level. Total standard deviation was 2.77 and 1.23 in aeration and gravity, respectively. In chromite sand system, average GCS varied from 26.25 to 33.21 in aeration and 25.16 to 31.97 in gravity. Average GCS was on its peak at the compactibility level of 30%. In case of lake sand, average GCS varies from 19.13 to 23.9 in aeration and 21.21 to 24.14 in gravity. Total standard deviation was 1.95 and 0.38 in aeration and gravity, respectively. Total average GCS in aeration was 22.37 whereas the same measure was 23.13 in gravity. Peak value for GCS was at 35% compactibility. Dotplot of GCS Technique Sand © o © RG o e • • A AA • A Olivine O •© • •. A«A * A • •© •• A*A AaA a, • • ••©• ssa«s •• ••• •••Aaaaaaa • A • Lake Aeration- • Choromite © 0 0 • Ceramic Media 0 0 • • A A • 3 ••© •• AA • 0 ••• • ••••A BA*AA o B«»iafl»|»i • ••••AaAAaaaaa AA A Gravity- 1 18 21 24 27 30 33 36 GCS Figure 30. Dotplot of GCS 98 In olivine sand, average GCS varied from 29.25 to 31.86 in aeration and 29.69 to 35.08 in gravity. Olivine appeared as a strongest sand system followed by chromite. GCS was on its peak either at 35% or 40% compactibility. GCS test results were similar in both of filling techniques, which indicates that there were lesser or no effects of aeration in GCS. Thus, aeration sand system can produce equally strong molds as compared to gravity. As a summary, no systematic trend was visible in GCS. Analysis of variance or ANOVA of the green compressive strength with respect to sand, technique and compactibility is shown in Table 10. The three-way interactions did not appear to have any practical significance and were removed from consideration with the same logic used previously in permeability. Table 10. ANOVA: GCS versus Sand, Technique, Compactibility Factor Type Levels Values Sand fixed 5 Ceramic: Media, Choromite , Lake, Olivine, RG Filling Technique fixed 2 Aeration, Gravi ty Compactibility (%) fixed 3 30, 35, 40 Analysis of Variance for GCS Source DF SS MS F P Sand 4 1699.77 424.94 135.02 0..00 0 Filling Technique 1 2.37 2.37 0.75 0,.38 8 Compactibility (%) 2 64.75 32.37 10.29 0..00 0 Sand*Filling Technique 4 39.64 9.91 3.15 0..01 8 Sand*Compactibility (%) 8 297.27 37.16 11.81 0..00 0 Filling Technique*Compactibil.it y 1:% > 2 12.86 6.43 2.04 0..13 5 Error 98 308.44 3.15 Total 119 2425.10 S = 1.77408 R-Sq = 87.28% R--Sq(adj) = 84.56% As shown in Table 10, p-value for the interactions (Technique*compactibility) greater than 0.1 suggested no interactions between techniques and compactibility levels, whereas interactions between sand and other factors were still existed. The main effects 99 of individual factors were not interpreted, and ANOVA of individual sands, and post-hoc analysis was followed. ANOVA of individual sand is listed in Table 11. Table 11. ANOVA of Individual Sand: GCS versus Technique, Compactibility Factor Type Levels Values Technique fixed 2 Aeration, Gravity Compactibility fixed 3 30, 35, 40 Analysis of Variance for GCS: Lake Source DF SS MS Technique 1 3 .527 3. .527 1, .79 0, .197 Compactibility 2 80 .023 40. .012 20. .32 0. .000 Technique*Compactibility 2 5. .241 2. .621 1. .33 0. .289 Error 18 35. .444 1. .969 Total 23 124, .235 S = 1.40325 R-Sq = 71.47% R-Sq(adj) = 63.55% Analysis of Variance for GCS: RG Source DF SS MS F P Technique 1 3 .800 3.800 .18 0.157 Compactibility 2 6 .475 3.238 .86 0.185 Technique*Compactibility 2 9 .738 4.869 ,79 0.088 Error 18 31 .387 1.744 Total 23 51.400 1.32050 R-Sq = 38.94^ R-Sq(adj) = 21.97% Analysis of Variance for GCS Olivine Source DF SS MS F P Technique 1 10.428 10.428 6.93 0.017 Compactibility 2 38.636 19.318 12.84 0.000 Technique*Compactibility 2 36.977 18.489 12.29 0.000 Error 18 27.081 1.504 Total 23 113.122 S = 1.22657 R-Sq = 76.06% R-Sq(adj) = 69.41% Analysis of Variance for GCS: Ceramic Media Source DF SS MS F P Technique 1 4.779 4.779 1.04 0.321 Compactibility 2 46.501 23.251 5.07 0.018 Technique*Compactibility 2 52.973 26.487 5.78 0.012 Error 18 82.556 4.586 Total 23 186.810 S = 2.14160 R-Sq = 55.81% R-Sq(adj) = 43.53% Analysis of Variance for GCS: Chromite Source DF SS MS F P Technique 1 19.476 19.476 9.99 0.005 Compactibility 2 190.383 95.191 48.83 0.000 Technique*Compactibility 2 4.809 2.405 1.23 0.315 Error 18 35.092 1.950 Total 23 249.760 100 In the ANOVA Table shown above for GCS of individual sands, two-way interactions were in abundance. All sands had interactions except lake and chromite. For those sands with interactions, main effects of individual factors could not be evident. Main effects of the factors with no interactions could be interpreted individually. P-value for technique in lake sand was greater than the level of significance value (cc= 0.1) for the test. Thus, the levels of the techniques were not significant. In other words, main effect of aeration in GCS of lake sand was not different than that of gravity. In case of chromite, p- value (0.005<0.1) suggested the main effects of aeration were significant to that of gravity. Interaction plot of the means of GCS is presented in Figure 31. As shown in Figure 31, treatment means lines were crossed each other, which confirmed the interactions and the reasonableness of the results given in Table 11. 101 ID co u, 3 3 O T3 wo ep r CN £ _ 8 8 •<> «> «? CO OS oa CN O <-> CO •—'• ^ "~ "~ wN e CO co m m °° °° °° 0. 1 CaO .4=3 CN CN CN CN CN O 1) U s CO fa c oft h o bina t CO Q WO WO WO WO WO wo WO 00 a >> oi CN CN CN CO Iv. Iv. IV. WO CN o ^3 co CN CN CM CN CO CO CO CO CN CN o X> There were ten homogeneous subsets. Olivine was on the bottom of the list followed by chromites and identified them as a stronger system. Silica sands were relatively weaker system as they appeared on the top of the list. Subsets were overlapped and no trends for compactibility and techniques were observed. Mold Hardness Mold hardness is the resistance to the surface indentation of a mold. A scale similar to the Brinell hardness was used to measure the flat surface of the specimen; the results are summarized in Table 13. Table 13. Descriptive Statistics of Mold Hardness Sand Technique Compactibility Mean (#) Std. Deviation N 30 94.13 .85 4 Aeration 35 95.38 .48 4 40 97.25 .96 4 Ceramic Total 95.58 0.79 12 Media 30 99.75 1.71 4 Gravity 35 96.50 .58 4 40 100.00 .82 4 Total 98.75 1.14 12 30 96.75 .50 4 35 4 Aeration 95.25 .50 40 95.00 .82 4 95.67 12 Chromite Total .63 30 95.00 2.00 4 35 4 Gravity 95.75 .96 40 95.50 2.38 4 Total 95.42 1.88 12 30 93.00 1.41 4 35 4 Aeration 94.50 1.29 40 97.50 1.29 4 Lake Total 95.00 1.33 12 30 92.75 1.26 4 Gravity 35 93.00 .82 4 40 96.00 1.41 4 Olivine 30 99.25 1.50 4 35 98.00 .82 4 103 Table 13 - Continued Compactibility Mean Std. Deviation N 40 94.00 2.94 4 Total 97.08 1.96 12 30 93.50 1.73 4 Gravity 35 93.25 1.26 4 40 98.00 .82 4 Total 94.92 1.32 12 30 96.38 3.42 8 Total 35 95.63 2.72 8 40 96.00 2.93 8 Total 96.00 3.04 24 30 89.50 1.29 4 Aeration 35 93.00 2.16 4 40 98.50 .58 4 Total 93.67 1.49 12 30 89.25 .96 4 Gravity 35 94.50 1.00 4 40 96.75 1.71 4 RG Total 93.50 1.27 12 30 89.38 1.06 8 Total 35 93.75 1.75 8 40 97.63 1.51 8 Total 93.58 1.47 24 30 94.53 3.56 20 Aeration 35 95.23 1.99 20 40 96.45 2.21 20 Total - Total 95.40 2.68 60 30 94.05 3.78 20 Gravity 35 94.60 1.64 20 40 97.25 2.15 20 Total 95.30 2.68 60 As shown in Table 13, ceramic media's average mold hardness number varies from 94.13 to 97.25 in aeration and 96.5 to 100 in gravity. The highest value was at 40% compactibility level. In case of chromite, average mold hardness number varies from 95.0 to 69.5 in aeration and 95.0 to 95.75 in gravity. In lake sand, average mold hardness number varies from 93.0 to 97.5 in aeration and 92.75 to 96.0 in gravity. Total average mold hardness in aeration was 95.0 whereas same measure was 93.92 in gravity. In olivine sand, average mold hardness number varies from 94.0 to 99.25 in aeration and 93.25 to 98.0 in gravity. In round grain (RG) sand, average mold hardness number varied from 89.5 to 98.5 in aeration and 89.25 to 96.75 in gravity. Position of different sand 104 systems in mold hardness scale is shown in Figure 32. As in the previous dot plots presented for permeability and GCS, mold hardness data points for aeration and gravity are presented in different panes. Types of sand grain are shown in the legend. Dotplot of Mold Hardness Technique Sand 3> • © RG • • © A Olivine • © • • A A • Lake • • A A o • • • A © A • a • A © • Choromite • ••••• o © • Ceramic Media Aeration - o o A s • • • • «>• • • • • A A © 9 © S & Q • © A A • A A A • A • • s A • • A • • A A**aaaAa* s • •••••A** © © © < J Gravity 88 90 92 94 96 98 100 102 Mold Hardness Figure 32. Dotplot of Mold Hardness As shown in Figure 32, data points were similarly distributed in both the panes. In mold hardness number no systematic trend existed. To compare and differentiate the main effects of the factors on mold hardness, ANOVA was conducted. As shown in appendix C, three-way interactions appeared. With very small SS the three-way interactions did not appear to have any practical significance and were removed from consideration. SS of the three way interactions were then accumulated into the error's SS. The resulting ANOVA without three-way interaction is shown in Table 14. 105 Table 14. ANOVA: Mold Hardness versus Sand, Technique Factor Type Level- S Values Sand fixed 5 Ceramic Media, Choromite,, Lake, Olivine, RG Filling Technique fixed 2 Aeration, Gravity Compactibility (%) fixed 3 30, 35, 40 Analysis of Variance for Mold Hardness Source DF SS MS F P Sand 4 184.217 46 .054 14.59 0..00 0 Filling Technique 1 0.300 0 .300 0.10 0..75 9 Compactibility (%) 2 142.813 71 .406 22.62 0..00 0 Sand*Filling Technique 4 95.617 23 .904 7.57 0..00 0 Sand*Compactibility (%) 8 229.208 28 .651 9.08 0..00 0 Filling Technique*Compactibil:i-t i' (:% > 2 12.262 6 .131 1.94 0..14 9 Error 98 309.383 3 .157 Total 119 973.800 S = 1.77679 R-Sq = 68.23% R-•Sq(adj) = 61.42% P-value for interactions (technique*compactibility) was greater than then standard (0.149 < 0.1) signified no interactions between techniques and compactibility levels, whereas other interactions were exist with less than 0.1 p-value, and the main affect of individual factors was not interpreted. ANOVA for individual sand, and post-hoc analysis of the combinations were carried out for further investigation. ANOVA for the individual sand is displayed in Table 15. Table 15. ANOVA of Individual Sand: Mold Hardness versus Technique, Compactibility Analysis of Variance for Mold Hardness: Lake Source DF SS MS F P Technique 1 7.042 7.042 4.41 0.050 Compactibility 2 66.083 33.042 20.69 0.000 Technique*Compactibility 2 2.083 1.042 0.65 0.533 Error 18 28.750 1.597 Total 23 103.958 S = 1.26381 R-Sq = 72.34% R-Sq(adj) = 64.66% Analysis of Variance for Mold Hardness: RG Source DF SS MS F P Technique 1 0.167 0.167 0.09 0.771 Compactibility 2 272.583 136.292 71.11 0.000 Technique*Compactibility 2 10.583 5.292 2.76 0.090 Error 18 34.500 1.917 Total 23 317.833 bl = lio38444 K-blw = 891015% K-HM($BO) = 86iol3% 106 Table 15-Continued Analysis of Variance for Mold Hardness: Olivine Source DF SS MS F P Technique 1 28.167 28.167 10.04 0.005 Compactibility 2 2.250 1.125 0.40 0.675 Technique*Compactibility 2 115.083 57.542 20.51 0.000 Error 18 50.500 2.806 Total 23 196.000 S = 1.67498 R-Sq = 74.23% R-Sq(adj) = 67.08% Analysis of Variance for Mold Hardness: Ceramic Media Source DF SS MS F P Technique 1 60.167 60.167 62.33 0.000 Compactibility 2 29.521 14.760 15.29 0.000 Technique*Compactibility 2 20.771 10.385 10.76 0.001 Error 18 17.375 0.965 Total 23 127.833 S = 0.982486 R-Sq = 86.41% R-Sq(adj) = 82.63% Analysis of Variance for Mold Hardness: Chromite Source DF SS MS F P Technique 1 0.375 0.375 0.19 0.667 Compactibility 2 1.583 0.792 0.40 0.673 Technique*Compactibility 2 6.750 3.375 1.72 0.207 Error 18 35.250 1.958 Total 23 43.958 S = 1.39940 R-Sq = 19.81% R-Sq(adj) = 0.00% As shown in Table 15, chromite and lake sand did not have interactions. Main effects of their individual factors could be interpreted. In chromite, p-values for both the compactibility and technique were greater than (0.1) standard significance level. Main effects of their means were equal, as stated in the null hypothesis. Techniques were producing no difference in the mold hardness. The main effects of the means of three levels of compactibility were also equal and suggested no difference in mold hardness while changing the compactibility levels. For the remaining sand system main effects of the means of the combinations needed to be interpreted due to the presence of interactions between the factors. The interactions are presented graphically in Figure 33. 107 Figure 33. Mold Hardness of Different Sands, Techniques and Compactibility Level As shown In Figure 33, treatments means of the five sands were crossed each other and displayed the interactions, and confirmed the reasonableness of the result presented in Table 15. SNK test result is displayed in Table 16. Table 16. Student-Newman-Keuls: Mold Hardness Subset Data N 1 2 3 4 5 6 7 8 9 1 1 0 1 RG30 4.0 89.3 RA30 4.0 89.5 LG30 4.0 92.8 LA30 4.0 93.0 93.0 LG35 4.0 93.0 93.0 RA35 4.0 93.0 93.0 OG35 4.0 93.3 93.3 OG30 4.0 93.5 93.5 93.5 OA40 4.0 94.0 94.0 94.0 94.0 MA30 4.0 94.1 94.1 94.1 94.1 LA35 4.0 94.5 94.5 94.5 94.5 94. 5 RG35 4.0 94.5 94.5 94.5 94.5 94. 5 108 Table 16 - Continued Data N Subset 1 2 3 4 5 6 7 8 9 10 11 CA40 4 95.0 95.0 95.0 95.0 95.0 95.0 CG30 4 95.0 95.0 95.0 95.0 95.0 95.0 CA35 4 95.3 95.3 95.3 95.3 95.3 95.3 MA35 4 95.4 95.4 95.4 95.4 95.4 95.4 CG40 4 95.5 95.5 95.5 95.5 95.5 95.5 CG35 4 95.8 95.8 95.8 95.8 95.8 95.8 95.8 LG40 4 96.0 96.0 96.0 96.0 96.0 96.0 MG35 4 96.5 96.5 96.5 96.5 96.5 96.5 CA30 4 96.8 96.8 96.8 96.8 96.8 RG40 4 96.8 96.8 96.8 96.8 96.8 MA40 4 97.3 97.3 97.3 97.3 97.3 LA40 4 97.5 97.5 97.5 97.5 97.5 97.5 OA35 4 98.0 98.0 98.0 98.0 98.0 OG40 4 98.0 98.0 98.0 98.0 98.0 RA40 4 98.5 98.5 98.5 98.5 OA30 4 99.3 99.3 99.3 MG30 4 99.8 99.8 MG40 4 100 Sig. .8 0.14 0.14 0.11 0.22 0.12 0.12 0.13 0.11 0.14 0.14 MeaiI Square (Error; = 1.84S ,df =9 0 As shown in Table 16, SNK test generated the homogeneous subsets of the combinations of mold hardness data. Majority of the subsets were overlapped to each other, which suggested the lack of complete distinction between the combinations. RG appeared at the top with 30% compactibility level followed by lake sand. These combinations were weaker mold hardness system. Ceramic media on the other hand positioned at the bottom of the list with the highest mold hardness. Combination with ceramic media, gravity and 40% compactibility produced the highest mold hardness of 100 units. A specific trend was not evident with respective to any of the factor. 109 Mold hardness test was devised to measure the degree of sand compaction. Higher mold hardness number means more sand compaction. Fundamentally, mold hardness relates closely with squeezing techniques. In this research, specimens were prepared by squeezing in a pneumatic squeezer and the variations that usually occur in 3-ram method were prevented. Minor difference among the sands and compactibility were due to the inherent property of individual sand and their shapes. Through the statistical analysis: descriptive and ANOVA, it was evident that the null hypothesis of equal means of different techniques individually could not interpreted. The post-hoc analysis of combinations exposed some similarities among the different combination but those combinations did not follow a specific trend for any factor. This implied the techniques under study; aeration and gravity were not significant. Bulk Density Bulk density of the green sand was measured in an AFS specimen tubes. The tubes were placed vertically under a funnel and the green sand was filled through a sieve. The tube was then compacted with a squeezer. Density was calculated by dividing the weight of the green sand by the volume of the tube (245 cm3). The same specimen that used to check the compactibility is usually used to determine the bulk density. As mentioned in the literature review, when water is added to the green sand for tempering, the clay starts swelling and the whole green sand mass expanded. The expansion caused a volumetric increase of the green sand, which reduces the bulk density. Average and standard deviations of this test results are shown in Table 17. 110 Table 17. Descriptive Statistics: Bulk Density (g/cm3) Sand Technique Compactibility (%) Mean Std. Deviation N Ceramic Aeration 30 1.194 0.030 4 Media 35 1.104 0.008 4 40 1.036 0.004 4 Total 1.111 0.018 12 Gravity 30 1.170 0.000 4 35 1.135 0.024 4 40 0.998 0.005 4 Total 1.101 0.014 12 Chromite Aeration 30 1.479 0.039 4 35 1.314 0.011 4 40 1.254 0.011 4 Total 1.349 0.024 12 Gravity 30 1.375 0.013 4 35 1.290 0.018 4 40 1.218 0.019 4 Total 1.294 0.017 12 Lake Aeration 30 0.993 0.013 4 35 0.970 0.008 4 40 0.933 0.010 4 Total 0.965 0.010 12 Gravity 30 0.982 0.009 4 35 0.915 0.013 4 40 0.870 0.027 4 Total 0.922 0.018 12 Olivine Aeration 30 1.059 0.009 4 35 0.972 0.009 4 40 0.911 0.007 4 Total 0.981 0.008 12 Gravity 30 1.118 0.013 4 35 0.978 0.005 4 40 0.915 0.010 4 Total 1.003 0.010 12 RG Aeration 30 1.160 0.034 4 35 1.108 0.022 4 40 1.010 0.016 4 Total 1.093 0.025 12 Gravity 30 1.113 0.017 4 35 1.048 0.013 4 40 0.983 0.010 4 Total 1.048 0.013 12 Total Aeration 30 1.177 0.173 20 35 1.094 0.129 20 40 1.029 0.125 20 Gravity 30 1.151 0.132 20 35 1.073 0.135 20 40 0.997 0.124 20 Total 1.074 0.130 60 Total 30 1.164 0.152 40 35 1.083 0.131 40 40 1.013 0.124 40 Total 1.087 0.136 120 111 As shown in Table 17, the average bulk densities of different sand systems were: ceramic media, 1.1; Chromite, 1.32; Lake sand, 0.94; olivine, 0.99; and RG, 1.07. Chromite was the heaviest, whereas lake silica was the lightest sand system. The trend of the bulk density of the green sand system appeared to be influenced by the density of the respective sands. Another observation from the table was that bulk density in each sand system was decreased with increased compactibility levels. In Figure 34, dotplot displays graphically the location of the different sands in a bulk density scale. Bulk density of sands in two filling techniques are displayed into two separate panel of the graph. Aeration is listed on the top and gravity on the bottom. Bulk density value in the horizontal axis is increasing from left to right. Dotpbt of Bulk Densfcy (g/cm3) Aeration © RG A olivine A • Lake • • Chrorrite A © • Cerarric Media A • #A O A* •©©•A OO • • A*A++0«A •• GO • • • Gravity so o© A A* A A* O • AA •• © ©GO • ••• A*0 O AAA** • • • i 1 1 i i i i 0.9 1.0 1.1 1.2 1.3 1.4 1.5 Bulk Density (g/cm3) Figure 34. Dotplot of Bulk Density 112 As shown in Figure 34, lake and olivine sand were clustered at the left side of the graph with lower bulk density, whereas chromite was distinguished from others by positioning at the extreme right in both the techniques. To further investigate ANOVA was conducted. In comparison to the main effects of the factors and other interactions, three-way interactions did not have any practical significance into the bulk density and was removed from consideration. The resulted ANOVA is shown in Table 18. Table 18. ANOVA: Bulk Density versus Sand, Technique Factor Type Levels Values Sand fixed 5 Ceramic Media, Chromite, Lake, Olivine, RG Technique fixed 2 Aeration, Gravity Compactibility (%) fixed 3 30, 35, 40 Analysis of Variance for Bulk Density (g/cm3) Source DF SS MS F P Sand 4 2.158219 0.539555 1930.37 0.000 Technique 1 0.036925 0.036925 132.11 0.000 Compactibility (%) 2 0.400140 0.200070 715.79 0.000 Sand*Technique 4 0.007905 0.001976 7.07 0.000 Sand*Compactibility (%) 8 0.034577 0.004322 15.46 0.000 Technique*Compactibility (%) 2 0.001938 0.000969 3.47 0.035 Sand*Technique*Compactibility (%) 8 0.017426 0.002178 7.79 0.000 Error 90 0.025156 0.000280 Total 119 2.682286 S = 0.0167185 R-Sq = 99.06% R-Sq(adj) = 98.76% As shown in Table 18, p-value for the three-way interactions was less than the standard (0.0<0.1) in ANOVA, which suggested the presence of three way interaction. Since the three-way interaction was present, the main affect of the individual factors could not be interpreted. The next step was to analyze the data by reducing the number of factors. Foundries usually select a sand system and control the green properties through the various tests. More than one sand system is normally not used in the same foundry, so analyzing the main affect of compactibility and techniques in individual sand was the best way to proceed. ANOVA for individual sand is displayed Table 19. 113 Table 19. ANOVA of Individual Sand: Bulk Density versus Technique, Compactibility Factor Type Levels Values Technique fixed 2 Aeration, Gravity Compactibility (%) fixed 3 30, 35, 40 Analysis of Variance for Bulk Density (g/cm3) Lake Sand Source DF SS MS F P Technique 1 0.0110082 0.0110082 ,97 0.000 Compactibility (%) 2 0.0295111 0.0147555 ,32 0.000 Technique*Compactibility (%) 2 0.0031406 0.0015703 ,27 0.005 Error 18 0.0038875 0.0002160 Total 23 0.0475473 S = 0.0146960 R-Sq = 91.82% R-Sq(adj) = 89.55% Analysis of Variance for Bulk Density (g/cm3) RG Source DF SS MS Technique 1 0.012150 0.012150 29.96 0.000 Compactibility (%) 2 0.079075 0.039538 97.49 0.000 Technique*Compactibility (%) 2 0.001075 0.000537 1.33 0.290 Error 18 0.007300 0.000406 Total 23 0.099600 0.0201384 R-Sq = 92.67? R-Sq(adj) = 90.63% Analysis of Variance for Bulk Density (g/cm3): Olivine Source DF SS MS Technique 1 0.001890 0.001890 20.20 0.000 Compactibility (%) 2 0.128702 0.064351 687,.7 4 0..00 0 Technique*Compactibility (%) 2 0.005239 0.002620 28,.0 0 0,.00 0 Error 18 0.001684 0.000094 Total 23 0.137516 ;3 S = 0.00967313 R-Sq = 98.78 O R-Sq(adj) = 98.44% Analysis of Variance for Bulk Density (g/cm3): Olivine Source DF SS MS F p Technique 1 0.001890 0.001890 20,.2 0 0,.00 0 Compactibility (%) 2 0.128702 0.064351 687,.7 4 0,.00 0 Technique*Compactibility (%) 2 0.005239 0.002620 28,.0 0 0,.00 0 Error 18 0.001684 0.000094 Total 23 0.137516 S = 0.00967313 R-Sq = 98.78!j. R-Sq(adj) = 98.44% Analysis of Variance for Bulk Density (g/cm3): Chromi te Source DF SS MS F p Technique 1 0.018040 0.018040 41,.8 8 0,.00 0 Compactibility (%) 2 0.151291 0.075646 175,.5 9 0,.00 0 Technique*Compactibility (%) 2 0.007476 0.003738 8..6 8 0..00 2 Error 18 0.007754 0.000431 Total 23 0.184562 S = 0.0207559 R-Sq = 95.80% Pl-Sq(adj ) = 94.63% Analysis of Variance for Bulk Density (g/cm3): Ceramic Media Source DF SS MS F p Technique 1 0.000662 0.000662 2,.5 4 0..12 8 Compactibility (%) 2 0.111927 0.055964 215..2 7 0..00 0 Technique*Compactibility (%) 2 0.005294 0.002647 10..1 8 0..00 1 Error 18 0.004679 0.000260 Total 23 0.122562 S = 0.0161237 R-Sq = 96.18? R-Sq(adj) = 95.12% As shown in the Table 19, less than the standard (0.1) p-value of the interactions in lake, olivine, chromite and ceramic media suggested the presence, and greater than 114 standard p-value, suggested the absence of the interactions between the factors: compactibility and filling techniques in RG. Since no interactions presented, main affects of the individual factors could be interpreted in RG. P-value for the technique and compactibility less than 0.1 suggested a significant difference among the levels of the factors in RG. The main affect of the average bulk density in aeration and in gravity was significant. Similarly, bulk densities at three different compactibility levels were also significant. For the remaining green sand system, the main effects of the combination needed to be explained due to the interactions. Bulk density versus compactibility plot is shown in Figure 35. Figure 35. Bulk Density of Different Sands, Techniques and Compactibility Level As shown in Figure 35, the lines were crossed to each other and confirmed the presence of interactions between the factors. Post-hoc SNK test is shown in Table 20. 115 00 CO co CM in CM C\J CM e en 3 s CM -ST Q 5 M "3 T- m I i- i- CM 3 2 If) CO O O $ o•>t ion |o 2 II i 4- c CM CM CO O O) O) c o i- CM CM ll O) O) O) CO odd E CD 1 Kt^^^^^^^^^*^ttf^^*^**t*^t^t^^ .1 s 116 As shown in Table 20, SNK test generated eighteen homogeneous subsets of the combination data of the bulk density. Lake and olivine sand appeared at the top with the lower bulk density, whereas chromite was on the bottom of the list with the highest bulk density. The higher compactibility levels preceded the lower, and suggested the bulk density was higher at lower compactibility. This suggested lower compactibility level was better to get the denser mold for all sands in any filling technique. Similarly, a trend in the techniques for given sand was evident. For example in chromite, aeration was listed after gravity for the same compactibility level and revealed that aeration filled mold had higher bulk density than the gravity filled. Although the bulk density was influenced by all factors: sand, techniques and compactibility, sand type was the dominant factor by the inherent difference in the sand density. Friability Friability is the surface abrasive property of the green sand. Friability is measured as the percentage of the sand loss from the surface of the two specimens due to rubbing while rotating inside a drum. Due to the rotation of the drum, sliding contact among the surfaces of the specimen and the drum induce the frictional forces, which generate the surface wear on the specimens, and the specimens lose the sand grains. The amount of the loss is expressed as the percentage reduction in weight of the specimen. The amount of sand loss largely depends upon the bonding of the clay, which anchor the sand grains together. Summary data for friability is shown in Table 21 below. 117 Table 21. Descriptive Statistics of Friability Data Sand Technique Compactibility (%) Mean (%) Std. Deviation N 30 9.78 0.32 4 35 7.88 0.34 4 40 6.35 0.44 4 Aeration Total 8 0.370 12 30 15.55 1.05 4 35 10.98 1.61 4 Ceramic 40 9.05 1.43 4 Media Gravity Total 11.86 1.383 12 30 9.33 1.19 4 35 8.23 1.18 4 40 5.2 0.74 4 Aeration Total 7.58 1.058 12 30 21.93 0.86 4 35 11.08 1.56 4 40 7.18 1.33 4 Chromite Gravity Total 13.39 1.283 12 30 9.13 1.15 4 35 6.98 0.41 4 40 5 0.58 4 Aeration Total 7.03 0.780 12 30 31 3.37 4 35 16 1.83 4 40 9.9 1.25 4 Lake Gravity Total 18.97 2.329 12 30 9.03 1.42 4 35 8 1.22 4 40 5.68 0.39 4 Aeration Total 7.57 1.104 12 30 17.25 0.73 4 35 9.48 0.45 4 40 8.23 0.63 4 Olivine Gravity Total 11.65 0.614 12 30 9.45 0.54 4 35 7.48 0.9 4 40 7.38 1.18 4 Aeration Total 8.1 0.912 12 30 29.5 3 4 35 14 0.82 4 40 10.23 0.71 4 RG Gravity Total 17.91 1.842 12 30 9.34 0.94 20 35 7.71 0.91 20 40 5.92 1.09 20 Aeration Total 7.66 0.983 60 30 23.05 6.7 20 35 12.31 2.7 20 40 8.92 1.52 20 Gravity Total 14.76 4.262 60 30 16.19 8.39 40 35 10.01 3.06 40 40 7.42 2 40 Total Total Total 11.21 5.284 120 Technique) 118 As shown in Table 21, ceramic media's average friability varied from 6.35 to 9.78 in aeration and 9.05 to 15.55 in gravity. Total average friability increased from 7.7 to 12.66 when compatibility decreased from 40% to 30%. Total standard deviations were 8.0 and 11.86 in aeration and gravity, respectively. In chromite sand system, average friability varied from 5.2 to 9.33 in aeration and 7.18 to 21.93 in gravity. When compactibility reduced to 30% from 40%, average friability number increased to 15.63 from 6.19. Total standard deviation was 2.06 and 6.62 in aeration and gravity respectively. Total average friability in aeration was 7.58 whereas the same measure was 13.39 in gravity. In lake sand, average friability varies from 5.0 to 9.13 in aeration and 9.9 to 31.0 in gravity. Total standard deviation was 1.9 and 9.5 in aeration and gravity, respectively. Total average friability in aeration was 7.03 whereas the same measure was 18.97 in gravity. Total average friability number was increased from 7.45 to 20.06 when compactibility was decreased from 40% to 30%. In Olivine sand, average friability varies between 5.68 and 9.03 in aeration, and 8.23 to 17.25 in gravity. Total standard deviation was 1.77 and 4.21 in aeration and gravity, respectively. Total average friability in aeration was 7.57 whereas the same measure was 11.65 in gravity. Total average friability increased from 6.95 to 13.14 when compactibility decreased from 40% to 30%. In RG sand, average friability number varies from 7.38 to 9.45 in aeration and 10.23 to 29.5 in gravity. Total standard deviation was 1.29 and 8.87 in aeration and gravity, respectively. Total average friability in aeration was 8.1 whereas the same measure was 17.91 in gravity. Total average friability increased from 8.8 to 19.48 when compactibility was down by 10% from 40% to 30%. Figure 32 shows the dot plot. All the data points are below 10 percent in aeration whereas gravity data was spread from 5% to 31%. In gravity filling, silica sands are appeared in the high friability region. Friability of different sand is 119 presented in a dot plot as shown in Figure 36. The same format and symbols used in previous analysis are used to express the position of different sands in the friability spectrum. Dotplot of Friability Technique Sand 3 0 RG o 3 ? 1 A Olivine A A • Lake 11 • • Choromite 11 3 • 1*031 • • 0 3 • • Ceramic Media • ••3 • • • « A • • ••At Aeration- .•«..•» 3 3 119 AAA • 111 • 3 • ••3* 0 • 11 ••••t9G«A«A • 3 Gravity- lytllf'-ttflt , • • » , * a. 4* 8 12 16 20 24 28 32 Friability Figure 36. Dotplot of Friability As shown in Figure 36, it was evident that friability of the sand systems in different filling techniques oriented differently. In aeration, all sands were rested at the left side having the friability value less than 10%, whereas a wider spread (10% - 30%) in higher side was observed in gravity. As a summary of this data set, friability increased significantly with a decrease in compatibility. Higher friability means more sand erosion by molten metal flow. The eroded sand will flow with the molten metal and lodge into the pattern cavity and produced the casting defects. Thus, lower friability is desirable to get rid of erosion defects. AFS has set an industry standard of 10% friability. When the friability increases 120 beyond this limit, erosion related casting defects kicks off. In aeration, for all sands system friability appeared consistently below 10%. Standard deviation for aeration was also small in comparison to that of gravity. Silica sands appeared highly friable. Any sand with lower compactibility possessed higher friability. In general observation, aeration appeared less friable than gravity but those were not the only factors changed in these experiments. Compactibility, a crucial factor was also changed. Thus, further analysis was necessary to identify the main effects of the factors. These were the general observation of friability in different sand systems. To study the main effects of each factor, statistical analysis of variance was done. ANOVA gives the impact of the factors as well as the interactions among the factors if any. ANOVA is a best technique to compare and differentiate the impact of different factors. ANOVA for friability with 90% confidence level is shown in Table 22. Table 22. ANOVA: Friability versus Sand, Technique Factor Type Levels Values Sand fixed S Ceramic Hedia, Chromite, Lake, Olivine, RG Technique fixed 2 Aeration, Gravity Compactibility fixed 3 30, 35, 40 Analysis of Variance for Friability Source DF SS HS F P Sand 4 267.62 66.91 40.15 0.000 Technique 1 1511.59 1511.59 907.09 0.000 Compactibility 2 1626.17 813.09 487.92 0.000 Sand*Technique 4 311.84 77.96 46.78 0.000 Sand*Compactibility 8 183.53 22.94 13.77 0.000 Technique'Compactibility 2 667.52 333.76 200.29 0.000 Sand*Technique*Compactibility 8 177.13 22.14 13.29 0.000 Error 90 149.98 1.67 Total 119 4895.39 |s = 1.29090 R-Sq = 96.94% R-Sq(adj) = 95.95% In ANOVA for friability as shown in Table 22, p-values for all factors including interactions were zero. This revealed the three-way interactions between the factors: sand, 121 technique and compactibility and the ANOVA was unable to identify the impact of the individual factors and differentiate them. ANOVA for individual sand and post-hoc analysis was conducted. ANOVA for individual sand is listed in Table 23. Table 23. ANOVA of Individual Sand: Friability versus Technique, Compactibility Factor Type Levels Values Technique fixed 2 Aeratior I, Gravi-t y Compactibility fixed 3 30, 35, 40 Analysis of Variance for Friability: Lake Source DF SS MS F P Technique 1 854.43 854.43 283,.7 8 0,.00 0 Compactibility 2 663.75 331.88 110,.2 3 0,.00 0 Technique*Compactibility 2 313.53 156.76 52,.0 7 0,.00 0 Error 18 54.20 3.01 Total 23 1885.90 S = 1.73518 R-Sq = 97.13% R-Sq(adj) = 96.33% Analysis of Variance for Friability: RG Source DF SS MS Technique 1 577.22 577.22 273.47 0.000 Compactibility 2 517.48 258.74 122.58 0.000 Technique*Compactibility 2 328.18 164.09 77.74 0.000 Error 18 37.99 2.11 Total 23 1460.87 S = 1.45282 R-Sq = 97.40% R-Sq(adj) = 96.68% Analysis of Variance for Friability: Ceramic Media Source DF SS MS Technique 1 89.320 89.320 86.94 0 .000 Compactibility 2 101.556 50.778 49.43 0 .000 Technique*Compactibility 2 11.181 5.590 5.44 0,.01 4 Error 18 18.492 1.027 Total 23 220.550 S = 1.01359 R-Sq = 91.62% R-Sq(adj) = 89.29% Analysis of Variance for Friability: Chromite Source DF SS MS F P Technique 1 202.42 202.42 146.34 0,.00 0 Compactibility 2 364.68 182.34 131.83 0,.00 0 Technique*Compactibility 2 139.15 69.57 50.30 0,.00 0 Error 18 24.90 1.38 Total 23 731.15 S = 1.17609 R-Sq = 96.59% R-Sq(adj) = 95.65% Analysis of Variance for' Fri.ability : Olivine Source DF SS MS F P Technique 1 100.042 100.042 125.05 0.000 Compactibility 2 162.241 81.120 101.40 0.000 Technique*Compactibility 2 52.616 26.308 32.88 0.000 Error 18 14.400 0.800 Total 23 329.298 S = 0.894427 R-Sq = 95.63 % R-Sq(adj) = 94. 41% 122 In case of friability, interactions existed in all sand system irrespective to their shape and density. The interactions suggested that the techniques had different relationship with the compactibility at different levels. Aeration was acting differently than the gravity. The interactions are also shown in Figure 37. Figure 37. Friability in Different Sands, Techniques and Compactibility Level As shown in Figure 37, treatment mean of five sands were crossed each other, which revealed the interaction between the factors and confirmed the rationale of the results given in Table 23. Friability in aeration was changed with the change in compactibility, but the rate of change was small than in gravity. Average friability in aeration for a given compactibility was always lower than that of gravity. Post hoc analysis was performed to the combinations of these factors. Student- Newman-Keuls test result with homogeneous subsets is shown in Table 24. Duncan test 123 is listed in appendix D. Both of the test procedures created the same homogeneous subsets with the square error of 1.666. Table 24. Student-Newman-Keuls: Friability (%) Subset Data N 1 2 3 4 5 6 7 8 9 10 LA40 4 5 CA40 4 5.2 OA40 4 5.68 5.68 MA40 4 6.35 6.35 6.35 LA35 4 6.98 6.98 6.98 6.98 CG40 4 7.18 7.18 7.18 7.18 RA40 4 7.38 7.38 7.38 7.38 7.38 RA35 4 7.48 7.48 7.48 7.48 7.48 MA35 4 7.88 7.88 7.88 7.88 OA35 4 8 8 8 8 CA35 4 8.23 8.23 8.23 8.23 8.23 OG40 4 8.23 8.23 8.23 8.23 8.23 OA30 4 9.03 9.03 9.03 9.03 MG40 4 9.05 9.05 9.05 9.05 LA30 4 9.13 9.13 9.13 9.13 CA30 4 9.33 9.33 9.33 RA30 4 9.45 9.45 9.45 OG35 4 9.48 9.48 9.48 MA30 4 9.78 9.78 9.78 LG40 4 9.9 9.9 9.9 RG40 4 10.2 10.2 MG35 4 10.9 CG35 4 11.0 RG35 4 14 MG30 4 15.5 LG35 4 16 OG30 4 17.2 CG30 4 21.9 RG30 4 29.5 LG30 4 31 Sig. 0.13 0.15 0.11 0.11 0.13 0.10 1 0.15 1 0.10 Mean Square (Error) = 1.666, df = 90, Number of replications for each combination =4 As shown in Table 24, ten homogeneous subsets appeared for friability. Most of the subsets were overlapped, which showed one combination was included in more than one subset. Combinations with aeration were clustered at the top of the list, and suggested the lower friability. On the other hand, combinations with gravity were positioned at the 124 bottom with higher friability. Higher compactibility levels were the first in the list, which suggested lesser friability in higher compactibility for given sand and filling technique. Lake silica and RG were observed to be more friable than specialty sands as they were settled at the bottom part in the list. From this investigation, it was evident that friability of the aerated fluidized sand was significantly less than that of gravity filling. Other green sand properties such as green strength and permeability were not affected by aeration and remain similar to that of gravity. Bulk density appeared higher in aeration, but was more dominated by the sand type rather than the techniques or compactibility. It could be implied that aeration had lowered the friability without hurting other green properties. Therefore, aeration technique was the superior green sand filling technique over the gravity filling, and is capable of producing quality molds with a potential reduction in casting defects. Relationships between Friability and Compactibility Friability of silica sands in two molding techniques is shown in Figure 38, interactions effects was visible between the factors: technique and compactibility. As shown in the graph, change in friability with respect to compactibility was very high in gravity. Friabilities of aeration and gravity were comparable at 40% compactibility. Friability line in aeration appeared relatively horizontal in comparison to gravity. As the friability in aeration was less susceptible to the compactibility, a wider range of compactibility could be used in foundry. Gravity process dictated a very narrow band in foundries due to a minute change in compactibility yields significant impact in friability. 125 Scatterplot of Friability vs Compactibility 30 35 40 Lake RG 35 -f 30 Technique Aeration * 25 -» — Gravity 1° 20 •e : "- 15 10 i 5-^ 30 35 40 Compactibility(% ) Figure 38. Friability of Silica Sands Further, silica sands of two different shapes were used in the experiment. Lake sand was angular and RG was round in shape. Aeration equally filled the tubes in both cases and demonstrated similar friability. This means aeration was capable to fill lake and RG without discriminating their densities and grain shapes. Friability of specialty sands is shown in Figure 39. Friability vs Compactibility 30 35 40 Ceramic Media Choromite Olivine 25 -T Technique Aeration 40 30 Compactibility(%) Figure 39. Friability of Specialty Sands 126 As shown in Figure 39, olivine, chromite and ceramic media were chosen as representative specialty sands. Friability appeared significantly low in aeration filling also for these sand systems. Even in lower range of compactibility (30%), friability was still below 10%. In gravity, friability increased drastically when the compactibility was brought down to 30% from 35%. Chromite appeared higher friable than others in gravity but aeration behaved consistently in all of these sands. In case of aeration, friability trend was almost consistent throughout the compactibility range in specialty sands, which was also seen in silica sands. Hence, the aeration filling technique is equally effective in filling the sand of any type and shape. Comparison of Aeration with High-pressure and Gravity Filling Green sand properties test results of aeration and gravity filled sand showed no significance between the two, except friability. The impact on friability was also not entirely by the technique but also due to the interactions between the three factors: sand, techniques, and compactibility. In this section, the author was comparing aeration with gravity and high-pressure blow, simultaneously. For this comparison lake silica sand was selected as a base sand with 8% of bentonite clay as mentioned in chapter IV of this dissertation. Green sand properties were tested at the compactibility level of 38%, which is commonly used in silica sand foundries. In high-pressure blow system, AFS tubes were placed vertically under the sand hopper and blown through the regulated air pressure. Pressure in higher-pressure blow was set to 0.3 MPa, and it was at 0.1 MPa in aeration. In gravity filling, sand was directly filled into the AFS tube through as standard funnel containing a quarter inch sieve. The same vents opening used in aeration were mounted at 127 the bottom end of the tube in high-pressure blow fill to allow the air passage through the tube, which assist to enhance the filling. Friability test results of green sand from different filling technique are shown in Table 25. Number of experimental run is listed in the first column, and the friability of the three molding techniques: high-pressure blow, aeration, and gravity, are presented in second, third and fourth column of the table. High-pressure blow showed similar results to that of gravity filling for the silica lake sand. Table 25. Friability Data for High-pressure, Aeration and Gravity High-pressure Aeration Gravity Runs (0.3 MPa) (O.lMPa) 1 14.27 7.0 14.0 2 12.82 7.3 17.0 3 12.88 6.9 17.0 4 14.17 6.9 16.0 5 12.41 7.5 16.0 6 14.54 6.5 15.0 7 15.14 8.1 17.3 8 13.32 7.5 16.5 As shown in Table 25, three techniques were studied with eight replications each. Friability values were in the range of 12.4 - 15.1 in high-pressure blow, 7.0 - 8.1 in aeration, and 14 - 17.3 in gravity. Out of three molding techniques, aeration held the friability at the lowest levels followed by high-pressure blow. Average friability of all three filling techniques is shown as a bar chart and in a box plot in Figure 40 and 41. 128 Friability Plot 9fl -, e 15- 2 rs £ 10- «5 . Gravity High Pressure(0.3 MP a) Aeration (O.IMPa) Filling Technique Figure 40. Friability of Green Sand with Different Filling Technique Boxptat of Friability 17.5^ 15.0- i -S y i —-^| w 12.5- i !§ 10.0- LL. 1/ 7.5- i—-^C—I 5.0- Aeration Gravity High-pressure blow Techniques Figure 41. Boxplot of Friability Comparing Different Filling Techniques As shown in Figure 40, gravity and high-pressure blow system had the friability levels higher than the aeration. In addition, friability in both the conventional molding techniques: gravity and high-pressure blow were more than the 10% limit set by AFS. boxplot in Figure 41 displayed the relative position and spreads in the friability level of 129 different techniques. Further statistical analysis was carried out using Tukey test with 90% confidence interval to compare these data, and the test result is listed in Table 26. Table 26. Comparison of Friability in Aeration, Gravity and High-pressure Blow One-way ANOVA: Friability versus Techniques Source DF SS MS F P Techniques 2 338.091 169.046 207.01 0.000 Error 21 17.149 0.817 Total 23 355.240 S = 0.9037 R-Sq = 95.17% R-Sq(adj) = 94.71% Individual 90% CIs For Mean Based onPooled StDev Level N Mean StDev + + + + Aeration 8 7.213 0.494 (-*-) Gravity 8 16.100 1.125 (-*--) High-pressure blow 8 13.694 0.970 (-*-) 7.5 10.0 12.5 15.0 Pooled StDev = 0.904 Tukey 90% Simultaneous Confidence Intervals All Pairwise Comparisons among Levels of Techniques Individual confidence level = 98.00% Techniques = Aeration subtracted from: Techniques Lower Center Upper Gravity 7.750 8.888 10.025 High-pressure blow 5.344 6.481 7.619 Techniques + + + Gravity ( — High-pressure blow (- — *—) + — -3.5 0.0 .5 7.0 Techniques = Gravity subtracted from: Techniques Lower Center Upper High-pressure blow -3.544 -2.406 -1.269 Techniques + + + +- High-pressure blow (- _*_ -) H .5 0.0 3.5 7.0 As shown in the Table 41, when aeration was compared with gravity and high- pressure blow, the confidence interval of the difference around zero was all positive. That 130 means friability in aeration was significantly lower than the friability in gravity and high- pressure blow. In the similar comparison of gravity with high-pressure blow, the confidence interval of the difference around zero was all-negative. That means the friability in gravity was significantly higher than high-pressure blow. Boxplot of friability in Figure 37 also displayed the difference in the means along with the variability in different techniques. Gravity consisted high variability in test results, aeration had the least and high pressure-blow was in between. For the practical purpose, as mention by AFS friability above 10% was not desirable (AFS, 2000). Gravity and high pressure were different to each other, but both were above the 10% limit. Hence, friability in aeration was not only significant with gravity and high-pressure statistically, but it was well below the standard limit of 10%. This was desirable for better quality with the potential of reducing casting defects. Validation of Friability Test Results Similar study done by Makino et al, 2008, in Sinto, Japan, also found that aeration filled mold was less friable than the gravity filled mold (Makino, 2008). 30% compactibility level was used with Japanese sand and clay. The composition and the sand system were different than the sand and clay used in the current research. FBOX, a full- size aeration filling and molding machine was used to fill the sand into the mold. Experimental equipment and test results are shown in Figure 42. 131 ^3 5.4 Gravity Aeration a) FBOX Aeration Machine b) Friability Results Figure 42. Validation of Friability Results (Makino, 2008) As shown in Figure 42(b), friability of green sand using gravity filling was 9.3%, whereas aeration filled sand mold had the friability of 5.4 % using the same sand, clay, compactibility level, and other operating and environmental conditions. The average difference of 3.8% was a significant number in friability measure. This study endorsed and established the fact that irrespective the location, materials and operating conditions aeration produced molds with lower friability than conventional gravity filling. Implication of Lower Friability and Other Observations It was demonstrated that aeration had the lowest friability than any other conventional molding techniques. Lesser friability facilitate in lowering the compactibility level from existing 35% - 40% to 30% - 35% range. This study revealed that aeration could produce a quality molds as good as other conventional molding 132 techniques with sufficient green sand properties. In addition, Aeration could produce the mold at lower compactibility levels than the existing molding techniques. Lower compactibility in sand molding has multiple benefits. From the process engineering perspective, it facilitates pattern release from the mold and does assist in mold shake out after the solidification, which enhances the productivity. The Lower level of moisture and friability serve to reduce molding defects and enhance the quality of the castings. Lower compactibility level in green sand molding requires less moisture content and/or clay. Lower compactibility requires less moisture content in the green sand, and generates lesser amount of steam during metal pouring. This reduces the probability of gas trap into the molten metal and avoids the potential blowhole defects in the casting. Lesser clay requirements reduce the clay consumption, which provides cost as well as environmental benefits. Due to the high demand, price of the clay is continuing to rise, and to meet the demand clay mining is increasing. Due to the greater excavation, a natural deposit of clay is rapidly depleting. Concern about the clay deposit's depletion hurting the geological balances of the mining areas is increasing among the industry experts and the environmentalist. The resulting imbalances in the earth crust might endanger the environment of the whole region. Lessening the consumption reduces the demand, which lowers the clay mining from its deposit and saves the environment from an inevitable disaster. Filled density is another interesting green sand property. Commonly, filled density of high-pressure blow is considered higher than that of other process. It may be worthwhile to mention a separate study done by Makino, et al, 2003. They studied the filling density distribution of above mention three molding techniques with similar set up 133 of vertically orientated tubes of varying diameter in different locations in the mold (Makino, Hirata, & Hadano, 2003). This study revealed higher density and uniform mold in aeration filling. Smaller diameter tubes were filled as entirely as the larger diameter tubes in aeration. In case of high-pressure blow, larger diameter tubes under the nozzles were filled with greater compaction and bear higher density whereas tubes away from nozzle were not filled enough. Unequal density distribution in blow system may be due to the sand compaction in the upper part of the hopper. The compacted sand becomes lumps and restricts the sand flow. In aeration, sand spreads and expands by the fluidization effect and breaks the lumps (if any) and increases flowability. Good flowing sand reaches all corners and deep pockets, which consequently produces molds with lesser density variations and the uniform fill. Makino, et al, 2003 studied this physical process with the vertically oriented tubes, and Ramrattan, et al, 2008, experimented with vertical nozzle and horizontal tubes, got the similar results. This suggested that the aeration could fill sand in any orientation with uniform density distribution, and exhibited significant advantages over other conventional filling technique. Aeration technique with lesser friability seemed promising from this investigation, and casted a ray of hope to the researchers and the foundries, which might enable them to make a mold at lower compactibility levels with cost and quality benefits. The author focused the investigation on the aeration molding technique in the following sections, which included optimizing green sand properties of the aeration mold, investigating the cause of lower friability, assessing the behavior of aeration-fluidized sand in elevated temperature, and validating the results with a test casting. 134 Optimizing Green Sand Properties of Fluidized Sand in Aeration In the previous section of this dissertation, green sand properties of the fluidized sand in aeration were evaluated and compared with that of conventional molding techniques. Some of the green sand properties appeared different in aeration than in conventional techniques. As listed in literature review chapter of this dissertation, moisture, clay, sand addition, and carbonaceous materials are the main constituents in green sand molding system, which govern the mold quality (Krysiak, 1994). An optimum use of these parameters is essential to ensure the defect free molds and castings. These parameters are equally pertinent in aeration, and the same sand control philosophy was followed in optimizing the green properties of the fluidized sand in aeration. In this research, the scope was defined to examine the green properties of different sand without pouring the molten metal in to the mold. Green sand used in this research never faced the high temperature situation of metal pouring and solidification. Saying that, the green sand never encountered the situation of loosing clay by burning, and diminishing of carbonaceous materials by vaporization, as well as degradation of sand particles as a consequence of its exposure and interaction with metal (if any was assumed to be minimal). In that situation, three factors - clay, sand addition and carbonaceous materials- were assumed to remain unchanged and treated as constants. After considering these facts, moisture is the only parameter, which is changing in this study to get a target compactibility level. Green sand properties determine the quality of a mold, and green properties are dependent on the compactibility (AFS, 2000). In other words, mold quality is the function 135 of compactibility. From this fact, for a prescribed level of mold quality, each green property should be within certain limits. Now, it is essential to figure out the single optimal value of the compactibility, which satisfies all these green properties' limits, and ensures the quality mold. Sand system running at the optimal compactibility level with the given conditions and parameters would be able to deliver the quality castings. Various relevant standard AFS green sand test were conducted, and the results were recorded for the analysis. Permeability, GCS and mold hardness, bulk density and friability were the five major test used in this research. Permeability measures the venting characteristics of the mold. GCS gives the feel about the ability of the mold to withstand the loads during mold handling, and maintaining the mold shape. Mold hardness was chosen as a measure of surface indentation, where as friability gave the surface abrasive property of the mold surface. Most of these green properties are expected to have some relationship to compactibility, as they were appeared dependent to compactibility. Sand molds in Michigan are built in the range of 35% - 40% compactibility levels for the conventional molding. This was established as an optimal working range from several years of trial in different foundries (Ramrattan, 2009). Compactibility lower than this was accompanied by erosion, cuts and washes, cope down, penetration and inclusion defects. Friability also becomes an issue at lower compactibility levels. Compactibility exceeding the given range generates moisture related gas defects and oversize castings. Additionally, a higher compactibility mold is difficult to shake out after solidification and hurts productivity (Krysiak, 1994). In other words, friability does not allow the compactibility to go below 35% and moisture content does not let it exceed 40%. In aeration, friability was shown to be less extreme than in conventional molding at lower compactibility levels, and might not be an issue when reducing the compactibility level 136 below the existing lower limit of conventional molding. From the cost and environmental viewpoints it is advantageous to lower the compactibility unless it hurts green properties. Lowering compactibility levels in molding without hurting green sand properties would provide a niche to produce castings with better surface finish and greater accuracy. A working range of the operating parameter for aeration is essential for the better sand control and to garner the benefits. Compactibility was chosen for optimization because it was proven to be successfully to detect minute changes in sand systems, and is established as an unparalleled critical control factor in mold quality. In this section, the optimal level(s) of compactibility to improve the desirable green properties and reduce related casting defects was investigated. By changing the moisture content, compactibility, a reference green property in sand control was changed to different levels to evaluate the green sand properties of the aeration filling technique in this study compactibility then was treated as an input variable (treatment) and Green sand properties as response. Compactibility is plotted on the horizontal axis and various green sand properties are on the vertical axis. Compactibility of the green sand was changed from 10% - 60% by adding water, and was mulled for three minutes after each water addition according to the standard procedure of the green sand preparation. For each level of compactibility, green sand was filled into the flask by the aeration technique and green sand properties of the mold were tested. The relationship between compactibility and green sand properties from the test results are shown in Figure 43. 137 Figure 43. Compactibility versus and Green Sand Properties in Aeration As shown in Figure 43, permeability number had a positive linear relationship with compactibility, and displayed a significant improvement at higher compactibility levels. Although permeability appeared more sensitive to compactibility than other green properties, it has no practical significance. The higher number was due to the higher scale of the measurement. For example, increase in permeability number from 50 to 100 appears considerable numerically, but it could hardly bring any improvement practically. The permeability number in a sand mold could be found in the range of 40 - 400. This is a very broad range in comparison with the other green sand property values. For example, 138 friability percent value appears in the range of 1 - 30, GCS is in the range of 10-50 psi, and bulk density normally lies in the range of 50-250 lbs/ft3, depending on the types of the sand. Therefore, a large observed change in permeability with compactibility is not as significant as a minor change in friability (2-5%) in terms of casting quality. While comparing green sand properties, friability, bulk density, and strength are more vital than permeability. While comparing green sand properties, looking different test results through the same window might be detrimental. However, the combined graph is helpful for the general understanding. Bulk density has a negative nearly linear relationship with compactibility. In Figure 37, bulk density varies from 40 - 100 lbs/ft3. Green compressive strength (GCS) increases with compactibility to about 25-30% compactibility and then decreases. Friability, on the other hand, increases significantly with the decrease in compactibility. The rate of decrease is higher below a compactibility level of 30%. In addition, this figure implies that changing only compactibility is not enough to get the desirable green sand properties. For example, in case of heavy section castings, a higher bulk density mold is needed to hold the heavy weight of the casting. The highest bulk density that can be achieved in the given sand system is 120 lbs/ft3, which is not enough. In such situations, sand with higher bulk density, such as chromite, is needed. In other words, Permeability and bulk density are more dependent on the sand type rather than the compactibility. This is also shown in the previous section. Although compactibility was considered as an independent variable and treated as a reference quantity to quantify other green sand properties, it was varied in the experiment with the addition of moisture. Figure 44 shows a typical relationship between the moisture and the compactibility in aeration. 139 Figure 44. Relationship between Moisture and Compactibility As shown in Figure 44, compactibility increases significantly with a minute increase in moisture content. In the given sand system, an approximately 1.5% increase in moisture content resulted in a 50% increases in the compactibility level. Normally, a 0.1% change in moisture content brings approximately 3% change in compactibility. The least count of moisture content available in the moisture test equipment was 0.1%. An increase of 5% compactibility levels was desirable to ensure the change of at least 0.1% in moisture content. As shown in previous sections, green sand properties such as permeability, GCS, mold hardness and friability were dependent upon three factors: techniques (aeration and gravity), sand, compactibility, and their interactions. For the aeration technique, sand and compactibility were the only two factors statistically influencing the green sand 140 properties. Due to the presence of interactions noted between sand and compactibility, the same compactibility levels might not be optimal in all sand systems. Therefore, an investigation to analyze compactibility within the individual sand system(s) was designed. The optimal working range could be determined from the respective green sand properties graphs. Compactibility was identified as an independent decision variable and all green sand properties were evaluated against it and plotted for the respective sand systems. Green sand properties of each sand system were considered and expressed in an individual graphs for each sand, since the relation between compactibility and green properties is not the same in all sand system. For example, at the 40% compactibility level, permeability of lake sand was 230 and the same value was 384 in chromit, and was expressed by two distinct equations. Although green sand properties of different sands did not have exactly the same value with respect to compactibility, the possibility of the similar relationship was existed. Regression analysis was used to explore the dependence. Figures 45-51 showed the regression equation and their respective statistics. These relationships were again expressed in Equations 19-50. Graphs were plotted with compactibility on the horizontal axis and green sand properties on the vertical axis. Three levels of compactibility, 30%, 35% and 40% were considered. As shown in Figure 37 friability was increased significantly below 30% compactibility level and crosses the 10% boundary set by the American Foundrymen Society (AFS). Similarly, Compactibility above 40% reduces the bulk density of the sand system significantly. In addition, higher compactibility level was resulted by the higher moisture content. Wet sand prohibits the flowability. 5% of equal spacing was decided from the fact that the compactibility in this research was controlled by the moisture addition and 0.1% moisture increase results in 141 the 3% (approximate) change in compactibility. 0.1% is the least count of the moisture testing equipment. To distinguish the moisture level, 5% of compactibility level was chosen. This is also established as a convention in the sand research. In Figure 45-51, the title of each graph includes the sand type and the relationship of the respective sand system. The first row in the title block is the sand type and the second row displayed the relationship between the green sand properties and compactibility as a simple linear regression equation. The sign of the slope in the regression equation displays the nature of the relationship between the compactibility and green sand properties in terms of a positive or negative relationship. Positive signs suggest positive or direct relationships - green sand property increases with compactibility, whereas negative signs suggest negative or inverse relationships - green property decreases when compactibility increases. The regression models with R2 values above 80% were considered well fitted. Although higher degree polynomials may fit better in a wide range of compactibility as shown in Figure 43, for the given range of compactibility (30% - 40%), simple linear regression was fitted well and was selected over the higher order for the sake of simplicity. The lower level of compactibility was set by the friability (further lowering compactibility will violate the AFS 10% friability limit) where as the higher side 40% was cut off set by the bulk density and moisture content. A discussion of each green property and their relationship with compactibility are presented in the following paragraphs. Bulk density is the weight of the sand mass in a given volume. Bulk density measures how tightly the sand grains are forced together, leaving smaller voids between the grains. The bulk density relationships of different sand systems are displayed in Figure 45. 142 Fitted Line Plot: Lake Fitted Line PlofcRG Bulk Density (g/cm3) = 1.175 - 0.006 Compactability (%) Bulk Density (g/cm3) = 1.617 - 0.01500 Compactability (%) 2.0 S 0.0105400 S 0.0265047 R-Sq 86.6% R-Sq 86.5% R-Sq(adj) 85.3% I" R-Sq(adj) 85.1% * 0.5 0.0 35 40 30 35 40 Compactability (%) Compactability (%) Fitted Line Plot: Olivine Fitted Line Plot: Chromite Bulk Density (g/cm3) = 1.498 - 0.01477 Compactability (%) Bulk Density (g/cm3) = 2.136 - 0.02250 Compactability (%) 2.0 2.0 s 0.0102204 1 5 R-Sq 97.7% 1.5 1 I ' R-Sq(adj) 97.4% H S 0.0354461 I" I''°0 51 R-Sq 89.0% I - R-Sq(adj) 87.9% 0.0 0.0 30 32 34 36 38 40 30 35 40 Compactability (%) Compactability (%) Fitted Line Plot: Ceramic Media Bulk Density (g/cm3) = 1.667 - 0.01589 Compactability (%) 2. S 0.0178416 R-Sq 94.1% R-Sg(adi) 93.5% tl 0.0 30 35 40 Compactability (%) Figure 45. Bulk Density-Compactibility Relationship of Green Sand in Aeration As shown in Figure 45, bulk density in aeration was higher at lower compactibility levels in all given sand systems. In 30% to 40% compactibility levels, bulk density appeared linearly dependent with compactibility. Each sand system possessed a unique relationship with compactibility and each has a different intercept and slope. The negative slope of the regression line showed the negative relationship between 143 the compactibility and the bulk density. To get the higher bulk density, lower compactibility was required. Higher bulk density is preferred in foundries for better surface finish and dimensional accuracy. Lower bulk density at higher compactibility was due to the swelling effect of the clay. The greater the clay swelling, the larger the voids developed between the sand grains, and more sand mass compaction occurs during compactibility tests. The same sand mass takes larger volumes in higher compactibility and gives lower bulk density. For given sand, the higher the bulk density, the better the surface finish and the greater was the dimensional accuracy. Following equations expressed the relationship between the compactibility and bulk density of various sands. Di = 1.175-0.006 Ci Equation 19 D2 = 1.617- 0.015 C2 Equation 20 D3 = 1.498-0.0147 C3 Equation 21 D4 = 2.136-0.0225 C4 Equation 22 D5 = 1.667 - 0.016 C5 Equation 23 Where, D was the bulk density, C was the compactibility, and the subscripts 1, 2, 3, 4, and 5 represents lake, RG, olivine, chromite and ceramic media, respectively. Moisture content in green sand determines the mold quality by influencing all green sand properties for a given sand system. Moisture content (MC) in a sand mass is expressed as a percentage of water in green sand by weight. Compactibility moisture relationship is shown in Figure 41 144 Fitted Line Plot: RG Fitted Line Plot: Lake Moisture Content (%) = 0.6500 + 0.04500 Compactability(%] loisture Content (%) = 0.5167 + 0.05000 Compactability (% 4 ~ 3 3 € • ^^__ . . o 2 2 S 0.103280 S 0.0758288 R-Sq 82.4% •K R-Sq 87.6% 5 R-Sq(adj) 80.7% 1 R-Sq(adj) 86.3% 30 35 40 Compactability (%) 30 35 40 Compactability (%) Fitted Line Plot:Olivine Fitted Line Plot: Chromite Moisture content (%) = 1.392 + 0.04000 Compactability(%) Moisture Content (%) = 1.008 + 0.035 Compactability (%) E 3 2 -•-— 1 o 2 S 0.0645497 2! R-Sq 85.5% «o H R-Sq(adj) 84.0% 30 35 40 Compactability (%) Compactability (%) Fitted Line Plot:Ceramic Media Moisture Content (%) = 1.315 + 0.03375 Compactability (%) 4 1 • 1 1 o 2- S 0.0542947 R-Sq 88.5% o R-Sq(adj) 87.4% 30 35 40 Compactability (%) Figure 46. Moisture Content-Compactibility Relationship of Green Sand in Aeration As shown in Figure 46, moisture content increased with compactibility in aeration as a usual observation in the foundry. The rate of increase of the moisture with respect to compactibility was given by the slope of the regression equation, which is displayed at the top of each panel. Although the general trend of moisture was rising with compactibility, the rate was not the same in all sand systems. A significant change in compactibility was 145 observed with a small change in moisture. For example, compactibility increased 5% when average moisture was raised 0.2 % (2.3%- 2.5 %) in ceramic media. The relationships between compactibility and moisture in aeration were expressed by the following equations. Mi =0.5167 +0.050 Ci Equation 24 M2 = 0.65 + 0.045 C2 Equation 25 M3 = 1.392 +0.040 C3 Equation 26 M4= 1.008 +0.035 C4 Equation 27 M5 =1.315 + 0.03375 C5 Equation 28 Where, M was the moisture content, and C was the compactibility level, the subscripts represented the sand type as described earlier. Higher moisture in higher compactibility was dictated by the swelling characteristics of the clay. Clay has an ability to absorb water up to 20 times to its dry weight. When it absorbs water it swells up and expands. As mentioned in chapter three of this dissertation, clay consists of layers of platelets and these platelets can be expanded or contracted with the addition or removal of water. When water is added, clay absorbs the moisture and holds it in between the platelets and swells. When the moisture is released, platelets get contracted and volume of sand mix decreases as well. The higher the expansion due to swelling, the greater will be the compaction, giving higher compactibility value. Moisture provides moldability to the green sand, but both excessively low and high moisture content creates casting defects. A specific level of moisture is required to induce desirable green sand properties with the effective use of clay. Excess water increases the plasticity of the mold and enhances moldability but gives rise to moisture-related casting defects. A lower moisture 146 level is advised once other green property requirements are met. Relationship between permeability and compactibility are shown in Figure 47. Fitted Une Plot: Lake Fitted Line Plot:RG Permeablity(#) = 189.2 + 1.025 Compactability (%) Permeability(#) = 156.2 + 0.9500 Compactability (%) 400 T s 1.74642 * 300 R-Sq 85.5% 2r R-Sq(adj) 84.1% ^ 30 35 40 Compactability (%) Compactability (%) Fitted Line Plot:Olivine Fitted Line Plot: Chromite Permeability (#) = 20.21 + 1.675 Compactability (%) Permeability(#) = 266.1 + 2.950 Compactability (%) 400 S 3.17083 & 300 R-Sq 84.8% jr R-Sq(adj) 83.3% S 200 ] 100 1 . 30 32 34 36 38 40 Compactability (%) Compactability (%) Fitted Line Plot: Ceramic Media Permeability(#) = 161.4 + 2.175 Compactability (%) 4001 * 300- • S 3.44783 R-Sq 88.8% R-Sq(adj) 87.7% 30 35 40 Compactability (%) Figure 47. Permeability-Compactibility Relationship of Green Sand in Aeration As shown in Figure 47, permeability increased with compactibility in all given sand systems. Higher compactibility was obtained by the greater swelling of the clay. Clay swelling pushed sand grains apart and developed a larger void in between. Larger voids 147 let an easy passage of air through the mold and higher permeability number demonstrated the behavior. Although the permeability number was not the same, its trend in all sand systems was increasing with compactibility. Moreover, the positive slope of the following regression equations suggested a positive relationship between permeability and compactibility. Pi = 189.2+1.025 Ci Equation 29 P2 = 156.2 + 0.95 C2 Equation 30 P3 =20.21+1.675 C3 Equation 31 P4 = 266.1+2.950 C4 Equation 32 P5 = 161.4 +2.175 C5 Equation 33 Where, P and C represented the permeability and compactibility, respectively, and the subscripts were for the sand types as explained earlier. Permeability is the measure of porosity in sand mold. Greater porosity with higher permeability numbers, allowed the easy gas passages through the mold to the atmosphere, and avoided the gas trap. Otherwise, gas generated due to evaporation of the moisture and organic materials would penetrate into the molten metal and become trapped, giving blows, pinholes, and other gas related defects. Low permeable mold produces better surface finish as the closely packed sand grains reduce the roughness on the mold wall. Green compressive strength (GCS) measures the strength of mold before drying. GCS is vital to keep mold shape and withstand various loads during mold handling. 148 Fitted Line Plot: Lake Fitted Line Plot: Lake GCS(psi) 11.23 + 1.035 Compactibility (%) GCS(psi) = 53.07 - 0.8020 Compactibility (%) 40 ^30 'in (5 S 0.555158 10 R-Sq 94.6% R-Sq(adj) 93.7% 0- 35 30 35 40 Compactibility (%) Compactibility (%) Fitted Line Plot: RG Fitted Line Plot: RG GCS (psi) = - 1.325 + 0.7600 Compactability (%) ^QGCS (psi) = 39.98 - 0.4200 Compactability (%) 40 n 30 a. 20 8 S 0.884590 10 R-Sq 86.0% R-Sq(adj) 83.7% 30 35 40 35 Compactability (%) Compactability (%) Fitted Line Plot: Ceramic Media Fitted Line Plot: Chromite GCS(psi) = 41.34 - 0.3081 Compactability (%) GCS (psi) = 53.90 - 0.6805 Compactability (%) 40 40 7 ! • s 30 -i 30 • • W20i 20 8 S 0.639448 s 1.34919 83.6% 10-1 R-Sq 82.3% 10 R-Sq R-Sq(adj) 80.5% R-Sq(adj) 81.9% 30 35 40 30 35 40 Compactability (%) Compactability (%) Fitted Line Plot:Olivine GCS (psi) = 39.31 - 0.2488 Compactability (%) 40 » a 30 1 Q. u S 0.373923 13 R-Sq 89.8% R-Sa(adi) 88.8% 30 35 40 Compactability (%) Figure 48. GCS-Compactibility Relationship of Green Sand in Aeration 149 GCS was associated linearly with compactibility for olivine, ceramic media and chromite sand as shown at the last three panes in the Figure 48. The general trend was decreasing GCS with increasing compactibility. In case of lake and RG, a different type of relationship exists. GCS was increased in the range of 30% to 35% compactibility levels and was decreased afterwards. Since, linear and quadratic regression models did not fit well, a piecewise linear function with breaking points was employed. The compactibility range was segmented and breaking points were identified as 30%, 35% and 40% to express the relationship by a piecewise linear function. After converting the non-linear relationship into a piecewise linear function, the problem could be treated as a linear (Winston, 2003). The following equations represent the relationship for the given ranges. GCSi = -11.23 + 1.035 Ci (30 GCSi = 53.07 -0.802 d (35 GCS2 =-1.325 +0.760 C2(30 GCS2 = 39.98 - 0.42 C2 (35 GCS3 = 39.31- 0.2488 C3 Equation 38 GCS4 = 53.9-0.681 C4 Equation 39 GCS5 = 41.34- 0.308 C5 Equation 40 For the lake and RG (Equation 34-37), the slope of the equation was positive in the first-half (30-35% compactibility) and negative in the second-half (35-40% compactibility) with the peak at 35% compactibility level. The peak GCS was due to the change in the strength of the clay with respect to the moisture content or compactibility. Clay bond became stronger with the addition of water till temper point giving rise in 150 GCS, and further water addition weakened the bond and dropped the GCS. This behavior of the clay bonding produced a peak in GCS. Every sand system possesses one such peak, but its location in the compactibility scale might be different. For example, lake and RG peaked at 35% compactibility, whereas olivine, chromite and ceramic media had possibly peaked before 30-40% range. The descending trends in regression justified the latter supposition. These sands might have a peak at the compactibility level of 30% or less; specific position was not verified due to the boundary set while defining the compactibility range. Moreover, peak GCS value might not always be good; rather operating on the peak value makes sand control more unstable. As long as the GCS satisfies strength requirements of the mold, operating in a flat portion is wise, which avoids the drastic shift in GCS and help to keep the sand system under control. Regression relationships of mold hardness with compactibility of different sands in aeration are expressed by the following equations. Hj = 114.3-0.55 Ci Equation41 H2 = 123.1 -0.850C2 Equation42 H3= 110.1-0.35 C3 Equation 43 H4 = 107.0 - 0.3250 C4 Equation 44 H5 = 106.4-0.313 C5 Equation 45 Where, H and C represented the mold hardness and compactibility, and the subscripts 1, 2, 3, 4, and 5 represented sand type lake, RG, olivine, chromite and ceramic media, respectively. The regression line is displayed in Figure 49. 151 Fitted Line Plot: Lake Fitted Line Plot: RG Mold Hardness = 114.3 - 0.5500 Compactability (%) Mold Hardness = 123.1 - 0.8500 Compactability (%) 100 100- 1- 1 75 n 75 S 1.61761 0) c R-Sq 84.7% ro£ 50 1 50-1 R-Sqfadjl 83.1% X S 0.917424 x •o o R-Sq 87.8% o R-Sq(adj) 86.6% 30 35 40 30 35 40 Compactability (%) Compactability (%) Fitted Line Plot:Olivine Fitted Line Plot:Chromite Mold Hardness = 110.1 - 0.3500 Compactability (%) Mold Hardness(#) = 107.0 - 0.3250 Compactability (%) 100 100 *" -* ¥75^ 75 30 35 40 30 40 Compactability (%) Compactability (%) Fitted Line Plot: Ceramic Media Mold Hardness(#) = 106.6 - 0.3125 Compactability (%) 100 75 S 0.602944 R-Sq 84.3% 50- R-Sq(adj) 82.7% 30 35 40 Compactability (%) Figure 49. Mold Hardness-Compactibility Relationship of Green Sand in Aeration Mold hardness for all given sand systems appeared linearly dependent with compactibility. Decreasing trends of the lines and negative slope in the regression equation suggested a decrease in mold hardness with an increase in compactibility. Higher mold hardness at lower compactibility level was due to the fact that sand grains were forced tightly together, leaving smaller voids between the grains to be squeezed. 152 Friability relates the surface toughness of the sand mold. Relation between friability and compactibility of various sands in aeration is displayed in Figure 50. Fitted Line Plot: Lake Fitted Line Plot: RG Friability (%) = 21.17 - 0.4025 Compactability (%) Friability (%) = 17.44 - 0.2725 Compactability (%) 30 30 S 0.693932 R-Sq 87.1% s 0.504851 £20 R-Sq(adj) 85.8% #20 R-Sq 85.4% R-Sq(adj) 83.9% I. • L 1 30 35 40 30 32 34 36 38 40 Compactability (%) Compactability (%) Fitted Line Plot: Olivine Fitted Line Plot:Chromite Friability (%) = 18.60 - 0.3224 Compactability (%) Friability (%) = 22.94 - 0.4377 Compactability (%) 30 30 T S 0.507982 S 0.714455 R-Sq 89.0% R-Sq 88.2% #20^ ^20 R-Sq(adj) 87.9% R-Sq(adj) 87.1% I,. 10 • • 30 35 40 30 35 40 Compactability (%) Compactability (%) Fitted Line Plot: Ceramic Media Friability (%) = 19.64 - 0.3332 Compactability (%) 30 S 0.386168 R-Sq 93.7% £20 R-Sq(adj) 93.1% 10 -» • 1 30 35 40 Compactability (%) Figure 50. Friability-Compactibility Relationship of Green Sand in Aeration Friability related linearly compactibility for the given range of 30-40% in all the sand systems under the study. Negative slope of the regression equations signified the 153 negative relationship. Friability is reduced with increasing compactibility. This could be explained with an insight on the test procedure and through the understanding of the role of the clay at mold surface. In the friability test, sand erosion at mold surface due to the rubbing action was studied. The frictional behavior of the two rubbing surfaces was investigated. By principle, frictional force between two rough surfaces increases with surface roughness, and the weaker surfaces experience greater wear. Avoiding solid-to- solid contact could minimize friction. In higher compactibility level, clay in the sand mix swells more and provides more clay-palettes to coat the sand grains. Larger clay coating avoids grain-to-grain and/or grain-to-metal-sieve contact and reduces the friction. Low frictional force caused less surface wear and sand loss. Moreover, sand grains were embedded into the clay and firmly anchored at the mold surface giving greater bonding strength. Strong mold surface could better withstand the frictional force and other adversities. Green sand at high compactibility levels attains a stronger bond to hold the sand grains together and a cushion on the surface to lubricate. This double action provided better erosive resistance in high compactibility level, but green sand with lower compactibility lacked both the cushioning and strength benefits of the clay and forced to have higher friability. The regression equations are given as follows: Fi = 21.17-0.403 Ci Equation 46 F2 = 17.44- 0.2725 C2 Equation 47 F3= 18.6 - 0.3224 C3 Equation 48 F4 = 22.94 - 0.4377 C4 Equation 49 F5 = 19.64 - 0.333 C5 Equation 50 Where, F and C represented friability and compactibility and the subscripts were for the sand type as described before. 154 From the regression analysis, bulk density, moisture content, permeability, mold hardness and friability appeared to be linearly (or piecewise linearly) dependent on compactibility. Moisture content and permeability increased with compactibility whereas bulk density and friability decreased. The change in green sand properties with compactibility was based upon the swelling characteristics of the clay. Water was the only factor that was varied in this experiment. Clay's bonding capacity and its behavior was dependent upon the amount of water it absorbed. The larger the water content the greater the swelling, which induced the voids between the two sand grains. For a given volume, green sand with greater voids weighs less, and produces low bulk density mold. On the other hand, larger voids in the sand mass provided an easy passage to vent the gases through the mold. Greater swelling of the clay platelets provides greater coating and better anchoring of the sand grains at the mold surface caused lower friability. On the contrary, lower compactibility due to low moisture, displayed higher bulk density and mold hardness. Low moisture in clay caused less swelling and sand grains were packed more closely together. Density of the sand grains was higher than the density of swelled clay. Green sand with closely packed grains had the higher bulk density, and mold hardness. From the casting quality perspective, lower moisture and friability are desirable, whereas higher bulk density, mold hardness and permeability enhance the dimensional accuracy, mold stability and venting. One of the objectives as mentioned in chapter three of this dissertation was to minimize the casting defects by optimizing green sand properties. Green sand properties were dependent on the compactibility, and were expressed in the previous paragraphs. From the graph and regression equations, it was observed that all green sand properties 155 were not at their best level at a single compactibility level. Some were better at lower, whereas others were better at middle or higher compactibility levels. In this situation, unique compactibility values would not be the best fit for all. Individual compactibility level for each green property could be analyzed statistically, but this would not bear any practical relevance. In practice, the sand system should be operated in a single compactibility level. Therefore, a tradeoff in green sand properties was essential and an optimal level of compactibility needed to be determined. Furthermore, a slight change in any ingredient of the sand system would alter the optimal compactibility level. In this research, five different types of sands were evaluated. Each sand type might have unique optimal compactibility levels different from each other. The graphs were constructed considering this fact that each of the sand will have their own optimal compactibility levels, where compactibility levels within sand systems were determined by their green properties and constraints. The regression equations of the green sand properties along with the other constraints were used in locating the optimal compactibility level for each sand system. As mentioned earlier, two types of constraints were identified. The first constraint type was the limits set by foundries for green sand property, and the second type was the limitations set by assumptions in this research. For satisfactory mold quality, desirable green property should be within a certain limit. Range of desirable green properties established by the sand research and foundry practice should be satisfied at a minimum. Although Variables normally have lower and upper bound, both limits might not be crucial in certain situations. All green sand properties might not have both the lower and higher limits for practical purposes. Friability has higher limits, whereas mold hardness has lower limits. From the sand molding literature, green properties are interdependent, 156 which was further verified by the experiment. If one green property increases the other green property might decrease. Moreover, lower limits of one factor might limit the higher side of the other. For example, if sand is compacted very hard, its mold hardness increases but permeability decreases. By high-density compaction, sand grains are forced tightly together giving a higher hardness number and leaving smaller voids for air passage producing lower permeability number. In this research, limits for green properties were selected from a typical foundry practice in Michigan. To minimize casting defects, permeability numbers above 200 are desirable in providing good venting characteristics. Green compressive strength of more than 18 psi is essential to hold the mold shape and its cavities, and withstand the abuse in mold handling. A mold hardness number of at least 90 is required to produce the casting dimensions close to the desired pattern size. Mold hardness less than 90 lacks stability, and causes mold wall movement and deformation, which gives oversized casting. Friability, less than 10 percent is good for avoiding sand erosion and inclusion defects. Bulk density plays a role in dimensional accuracy and surface finish, and it depends upon the density of the sand itself: silica is low-density, whereas chromite and ceramic media are high-density sands. Higher bulk density is better, but it might be accompanied by higher friability. Moisture content of 2.5 percent is considered enough to temper green sand and minimize moisture related defects (Ramrattan, 2008). Following is the summary list of the constraints used to optimize the green properties in aeration. • Permeability (#) > 200 • GCS (lb/in2) > 18 • Mold Hardness (#) > 90 • Friability (%) < 10 157 • Moisture content < 2.6 In addition to these constraints, green sand properties were studied between 30% and 40% compactibility levels, which restricted the interpretation and application of these results beyond these ranges. Compactibility levels in aeration were optimized by using to the regression lines and the constraints. As shown in graph, for olivine sand it is impossible to obtain 200 permeability numbers, the lower limit. From the literature and the sand data, olivine sand is considered as low-permeable sand, and had barely 100 permeability numbers. This disparity in the sand system was successfully detected and displayed. From this analysis, it appeared that the olivine sand system might not be able to satisfy the permeability limit. Based only on this deficiency, the use of olivine in molding and its importance with other benefits could not be underestimated and ignored the usefulness of olivine in molding. Other factors in molding such as processing parameters, mold design, and materials needed to be investigate, which could help in this regard. By altering these parameters it is possible to satisfy the permeability requirements and restore the position of olivine in the molding regimes. One area of improvement is reducing the generation of vapor and gases in the mold so that less passage is required to vent through the mold. Moisture content and organics in green sand are the two prime factors in these regards. Lower moisture level and lesser amount of organics in green sand reduce the gas generation and minimize the permeability requirements. Physical adjustments in the mold during the mold building process could enhance the permeability of the mold. Small artificial venting holes could be made on the cope of the mold, which provides extra passage for the gases and increases the permeability of the mold. Similar types of provisions are also incorporated in conventional molding practice. Similarly, RG also 158 possessed lower permeability due to the round shape of its grain. Round grains were packed closely together, allowing very small gaps to let the air pass. To meet the criteria of a permeability number of 200, additional venting was essential and use of the holes on the cope as described previously was recommended. With this recommendation, the permeability constraint was suggested to satisfy practically. After examining the respective constraints, mold hardness and GCS were satisfied in all levels of compactibility. In reality, friability restricts compactibility levels to the lower side and moisture restricts to the higher side. In other words, friability is critical at lower compactibility level whereas moisture is critical in higher compactibility. Once friability limit of 10% as prescribed by AFS is satisfied the lower level of the compactibility is recommended. In this experiment, the friability limit was met at a 30% compactibility level and is suggested as an optimal practical working range. Moisture content and bulk density pulled down the compactibility and set the maximum limits. In addition, lower friability, which normally requires higher compactibility, was also achieved at a lower compactibility level. Change in permeability with respect to compactibility was less significant. For example, permeability in olivine remained in the same range although compactibility was raised from 30% to 40%. To cope with the lesser permeability in olivine and to reduce gas defects, artificial venting was recommended. In summary, in the aeration molding technique, defects could be contained to a minimum by maintaining the prescribed standard level of green sand properties in the 30% compactibility level. In other words, aeration appeared to produce a quality mold successfully with the optimal working range of 30% compactibility for lake silica, round grain silica, olivine, chromite and ceramic media. This analysis suggested 159 that mold in aeration could be built with optimal green sand properties, and it could be equally employed in any sand system for given set of conditions and materials. The compactibility level recommended in aeration was lower than the existing level for conventional molding techniques. Moisture content and friability were the two crucial factors binding the compactibility level. Friability did not allow the compactibility to lower, and moisture content prohibited it to rise. In conventional molding, the optimal level of compactibility is 38%. In aeration, 30% compactibility was possible due to the lower friability, which was below 10% (AFS standard). Normally, friability was the one to blame for the necessity of higher compactibility, which was also shown in the previous section of this dissertation. The friability in gravity and high-pressure blow was above 10% while lowering compactibility below 38%. Once friability requirements met, molds could be made at a lower compactibility level by satisfying all green sand properties. This revealed the fact that aeration not only produces the quality molds but also it does so at lower compactibility levels, which was impossible with the conventional molding techniques. The benefits of molding at lower compactibility are two-fold. Lower compactibility requires low moisture content and provides dense mold. Moisture in green sand is vaporized when it comes in contact with hot molten metal. Such abruptly vaporized water trapped in the molten metal produces the blowholes and pinholes in the casting when the metal solidifies. In addition, higher moisture levels increase the plasticity of the green sand and increase the probability of mold wall movement or deformation, which leads to distorted casting. Lower moisture is beneficial to get rid of these defects. High-density mold on the other hand provided the dimensional stability, and help to produce near-net shape castings with greater details and accuracy. From this 160 study aeration could produce not only the quality molds but also made sand molding possible at lower compactibility, which was not possible by the conventional molding techniques. Friability versus Other Green Sand Properties in Aeration Friability was the crucial factor in determining the optimal working range of compactibility for aeration system under study. As shown in Figure 43, friability was increasing with the decrease in compactibility. From cost and other benefits, working in low compactibility is better, but, when compactibility was decreased, friability was increased rapidly and crossed the 10% boundary set by AFS. Friability was already beyond this limit even at 35% compactibility level in gravity. Thus foundries had set a convention of operating in the range of 35% - 40% compactibility levels. The situation was changed in aeration, and the friability was well below the 10% limit even if the compactibility was reduced below this range. It is now possible to operate in or above 30% compactibility level in aeration. Going higher compactibility means losing the opportunities to save the cost and other benefits along with increasing the chances of moisture related casting defects. Since compactibility depends on the moisture, higher compactibility level contains more moisture in the sand. Without violating the 10% rule of friability and minimizing the moisture related defect, it was already established in this dissertation that to operate in the range of 30% - 35% compactibility levels in aeration was possible and recommended as the optimal working range, which met the green sand properties criteria and provided the cost and other environment benefits, such as saving in clay consumption, eliminating the use of hazardous chemicals in sand etc. 161 From this study, friability appeared as a sensitive factor to the changes in compactibility of a green sand system. It might be useful in sand control if other green properties could be estimated from the test results of the friability in a green sand system. In the following section, relationship between friability and other green properties were investigated. In Figure 51-55, friability is plotted on the horizontal axis and various green sand properties are on the vertical axis. Figure 51. Friability versus Green Properties of Lake Sand in Aeration As shown in Figure 51, when friability increased compactibility and moisture contents of the lake sand decreased significantly. The change in the other green sand properties-permeability, bulk density and mold hardness was small. Permeability decreases where as mold hardness and bulk density increases with friability. Changes in the green properties except compactibility and moisture were negligible practically. Lower level of moisture is desirable in sand molding, and forces friability to higher level. 162 Friability higher than 10% gives rise to the casting defects and not allowed. For the lake sand system with the given amount of clay, GFN and environmental conditions, moisture content in the range 2-2.25 is suggested. In other words, for a sand system with 8% clay content, 60 GFN with four sieve grain distribution, and the ambient conditions of 70o F temperature and 50% Relative humidity, moisture content in the range 2.0-2.25 produces the mold having less than 10% friability. In other words, once the friability test results are known, other green properties could be estimated using the friability graph for the specific conditions. For example, if the friability in sand is in the range of 8-10%, range of other green sand properties - moisture content: 2-2.25, compactibility: 30-32%, permeability: 180-190, mold hardness: 96-98, GCS: 20-22 psi and bulk density: 72-75 lbs/ ft3 could be deducted. In RG and olivine sand, relationship similar to that of lake sand existed between friability and other green properties, and is shown in Figure 52, and 53 respectively. Compactibility and moisture content where higher at lower friability. Moisture content of 2% or higher, keeps the friability less than 10% in RG whereas higher moisture content was required in olivine. 163 Friability vs. Green Properties Sand = RG 5.0 7.5 10.0 Permeability •••-•- GCS (psi •• * -• i , .— 5.0 7.5 10.0 5.0 7.5 10.0 Friability (%) Figure 52. Friability versus Green Properties of RG Sand in Aeration Friability vs. Green Properties Sand = Olivine 5.0 7.5 10.0 Compactibility (%) Moisture Content (%) Permeability 5.0 7.5 10.0 5.0 7.5 10.0 Friability (%) Figure 53. Friability versus Green Properties of Olivine Sand in Aeration 164 As shown in Figure 53, Olivine sand system with the given conditions as mentioned previously, had permeability of below 100 and bulk density of 65 lbs/ ft3. The relationship between the friability and other green properties in chromite sand and ceramic media are shown in Figure 54 and 55 respectively. Figure 54. Friability versus Green Properties of Chromite Sand in Aeration As shown in Figure 54, chromite sand had similar type of relationship between friability and other green properties to that of lake sand. Moisture content was higher at lower friability. Moisture content of 2.0% or higher, keeps the friability less than 10%. For this combination, chromite sand system will have permeability of 380 and bulk density of 90 lbs/ ft3 with the previously mentioned given conditions. 165 Friability vs. Green Properties Sand = Ceramic Media 5.0 7.5 10.0 Compactibility (%) Moisture Content (%) Permeability 45 40 35 30 25 Mold Hardness 100 754 50 5.0 7.5 10.0 7.5 10.0 Friability (%) Figure 55. Friability versus Green Properties of Ceramic Media in Aeration As shown in Figure 55, ceramic media has similar type of relationship between friability and other green properties that of other sands. Moisture content and compactibility were higher at lower friability. Moisture content of 2.25% or higher, kept the friability less than 10%. For this combination, ceramic media had the permeability around 250, and bulk density of 65 lbs/ ft3 with the given conditions. In conclusion, friability plot could be helpful to estimate the other green sand properties once the friability test results were available. Compactibility and moisture content changes rapidly with friability whereas permeability, GCS, bulk density, and mold hardness experienced a slight change. As shown in Figures 51-55, bulk density and permeability were varied principally with the change in the sand types. This suggested the foundries requiring high permeable mold should look for chromite or ceramic media. Similarly, foundries producing heavy section casting should look for higher bulk density 166 sand such as chromite. Once the sand type is determined and mixed according to the aforementioned composition and procedure, they could estimate the green sand properties by measuring the friability. Until now, the first two objectives of the dissertation comparing and optimizing the green sand properties of aeration were addressed. Next portion of this section covers the remaining objectives of dynamic test and material analysis. Advance Cone Jolt In advance cone jolt, drop height for the jolt can readily be changed. Force in term of number of impact versus displacement or deformation of the specimen can be plotted and recorded. From the force displacement curve, energy absorption before failure can be calculated. Advance cone jolt was developed to measure the toughness, a dynamic green sand property in foundry. Green silica sand with four different types of clay were tried to investigate its performance. Sand mixes were prepared by mixing different proportion of southern and western bentonite. Mix A, was 20% calcium bentonite and 80% sodium bentonite. Mix B was 80% calcium bentonite and 20% sodium bentonite. Composition of Mix C and D were the same to that of mix A and B, respectively, but samples were taken after running seven production cycles. In other words, samples for mix A and B were taken from the freshly prepared sand before using into the mold, whereas C and D were the recycled sand from the production molding lines. Test results are shown in Figure 43. 167 Cone Jolts vs. Deformation 130 • JU A Mix A Mf ^ » Mix B 90 • (# ) M/ A? "*— Mix C Mf ^p M Mix D Dlt S ^ 50" 10 1^* 0.0010 0.0020 0.0030 Deformation (m) Figure 56. Advance Cone Jolt Test Results of Different Clays Cone jolt test was able to pick the differences in various types of clay mix, which was not detected by other green strength tests. As shown in the figure above, Mix A was more plastic and weak, whereas Mix B was strong with little plastic deformation. Cone jolt number increased in both recycled sand. This concluded that cone jolt was able to detect the minor changes in sand system. Although cone jolt test was more sensitive than others, no difference was observed between the aeration and gravity. Test data for aeration and gravity are presented in Table 27. T-test at 90% confidence level for cone jolts data is as shown in Table 28. Table 27. Cone Jolt Results for Aeration and Gravity Runs Aeration Gravity 1 26 25 2 30 27 3 26 31 4 24 20 5 20 24 6 26 22 Compactibility = 38%, lake sand, clay = 8% Jolts/min= 100, drop height = 0.06 inch 168 Table 28. T-test of Cone Jolt: Aeration versus Gravity Two-sample T for Aeration vs Gravity N Mean StDev SE Mean Aeration 6 25.33 3.27 1.3 Gravity 6 24.83 3.87 1.6 Difference = mu (Aeration) - mu (Gravity) Estimate for difference: 0.50 90% CI for difference: (-3.29, 4.29) T-Test of difference = 0 (vs not =): T-Value = 0.24 P-Value = 0.814 DF = 9 P-value of this test was 0.814, which was distinctly greater than the significance level of 0.1. Hence, null hypothesis of equal mean was not rejected. Aeration and gravity had the equal mean and they were appeared not significant in cone jolt test. Test Results of Thermal Erosion Tester Thermal erosion tester was designed and built in Process evaluation lab at Western Michigan University (Ramrattan, 2008). The quest of developing this test was to study the sand clay behavior at elevated temperature while pouring the molten metal in the mold. This test was more relevant in studying erosion issue in aeration, because in the similar room temperature friability test, mold from aeration filling was appeared less friable than the conventional fill. As already mention in the methodology section of this dissertation, sand specimen was tested under a heated metal element (700°C). Lake sand with 8% bentonite clay and 38% compactibility level was used in the experiment. Amount of sand loss due to the erosion caused by the rubbing action of heated element on sand specimen was collected, and is displayed in Table 29. 169 Table 29. Thermal Erosion Test Results Amount of sand loss (g) Run Aeration Gravity 1 4.12 5.56 2 4.82 6.34 3 4.20 6.71 4 4.87 6.96 As shown in Table 29, four test replications were made to study the erosion in sand molds produced in aeration and gravity molding techniques. Amount of erosion was expressed in grams. The average erosion in aeration appeared less than in gravity. Further statistical analysis was conducted to for the confirmation, and the statistical test of comparing of two techniques is listed in Table 30 Table 30.One-way ANOVA: Sand Loss versus Technique in Thermal Erosion Test Source DF SS MS F P Technique 1 7.130 7.130 27.00 0.002 Error 6 1.585 0.264 Total 7 8.715 S = 0.5139 R-Sq = 81.82% R-Sq(adj) = 78.79% Individual 90% CIs For Mean Based on Pooled StDev Level N Mean StDev + + + + Aeration 4 4.5028 0.3963 ( * ) Gravity 4 6.3910 0.6092 ( * ) 4.00 4.80 5.60 6.40 Pooled StDev = 0.5139 As shown in Table 30, technique had p-value of 0.02, which was less than 0.1 significance level set for this test. Thus, null hypothesis of equal means of two techniques was rejected. Hence, aeration and gravity filling techniques were significant in erosion. This test supported the inference of the AFS friability test. The thermal erosion tester clearly detected the friability change and justified its relevance. 170 Sand Clay Interactions in Different Filling Mechanisms From the laboratory test and statistical analysis it was evident that aeration had some superior green sand properties. This section was devoted to investigate the sand clay interactions in different molding techniques and to identify the cause of lower friability in aeration. Results from X-ray Diffraction X-ray diffraction results of sand-clay mixture behavior under different filling mechanisms are shown in Figures 57-59. Figure 57 and 59 described the diffraction result for gravity filling and high-pressure blow filling, respectively, whereas Figure 56 displayed the diffraction pattern for aeration. By comparing these diffraction patterns with the standard International Centre for Diffraction Data (ICDD) (McClune, 2001) several observations were made. Strong directionality of the clay was observed in most of the samples that were not aerated. This is implied from the strong peak at 29 of 28.80, and the absence of other anticipated strong peaks was observed in the known aerated samples. The reason was that during aeration clay got isotropic, which made the peaks too small to be detected under the strong diffraction intensity of silica. Further, x- ray diffraction pattern showed that the intensity plot in aeration was more predictive and consistent in different runs, whereas there was run-to-run variation in gravity and high-pressure blow. This result led toward the conclusion that aeration system could produce the mold in a more consistent way with more isotropic mix of sand particles and clay platelets. 171 w c CD *-Jj ICO -Ii LJLL. I A-**, CD »ffwi IJM/ oc L^Jjua _* L ,*A>»ft«A- 20 30 40 SO 60 70 SO 30 100 110 26 Figure 57. Diffraction Pattern of Silica Sand and Clay Using Gravity Filling c _ctoo -Jl -1 ,* t . > * »_ JLJ Jtk«*A_ 1 ^ ^A. 20 30 40 50 60 70 SO 90 100 110 29 Figure 58. Diffraction Pattern of Silica Sand and Clay Using Aeration Filling CO c JS DC 'id •J—&»—i •» B. «» fl 20 30 40 50 70 80 90 100 110 26 Figure 59. Diffraction Pattern of Silica Sand and Clay Using High-pressure Blow 172 Ratio of the peak intensity with 29 at 21.8° and 28.8° in different samples were calculated and recorded as shown in Table 31, and the average values are displayed in Figure 60. Table 31. Intensity Ratio of Two Highest Peaks in Diffraction Pattern Aeration Gravity High-pressure Blow 4.23 4.19 4.2 3.8 1.49 2.51 4.23 2.78 2.86 Intensity Ratio 4.00 • Aeration High- • pressure <2 3.00 • Gravity Blow 2.00 Figure 60. Intensity Ratio Interval Plot As shown in Figure 60, average intensity ratios were 2.8, 3.2 and 3.9, for gravity, high-pressure blow and aeration specimen, respectively. Graphically, aeration seemed different than the other two conventional methods, and had the average closer to the ICDD's standard intensity ratio of 4.2. This suggested the homogeneous and isotropic distribution of the clay platelets in aeration. 173 Results of Scanning Electron Microscope (SEM) In an attempt to study the behavior under different filling techniques in micro scale and visualization, clay coating on sand grain was studied under SEM on the high-pressure blow and aeration specimens. As shown in Figure 61, clay platelets with discontinuous distribution was observed in high-pressure blow specimen. In addition, cracked and rough clay surfaces restricted the proper focusing of the SEM. Figure 61. SEM Picture High-pressure Blow Sand Specimen As shown in Figure 62, clay platelets appeared smooth and continuous throughout the sand surface in an aeration filled specimen, which suggested the uniform distribution of the clay into the green sand. 174 Figure 62. SEM Picture Aeration Sand Specimen This concluded that aeration helped in homogeneous clay distribution producing uniform coating. The purpose of clay was to bind the sand particles together. Homogeneous and uniform clay would yield better bond. From this fact, it could be inferred that grain-to-grain bonding strength in aeration filled specimen was higher in comparison to that of high-pressure blow filled specimen. Results of Universal Micro-tribometer (UMT) Universal Micro-tribometer was used to measure the bonding of sand grains at the surface of the specimen. In this procedure, a micro scale needle tip was used to scratch the specimen surface and resistance offered by the specimen was recorded. The UMT had 175 the facility to measure, record and display various parameters during the experiments such as friction or scratching force Fx, normal force Fz, electric contact resistance (ECR), acoustic emission (AE) etc, as a function of time in seconds. Only the scratching force was studied in this research to compare two filling techniques. Resistance or scratching force in high-pressure blow specimen is shown in Figure 63. Scratching Force Rot (Specimen without Aeration) 10 £ E 0 's: o 13 Time (9ec) Figure 63. Scratching Force Plot in High-pressure Blow Specimen with Vertical Load As shown in the Figure 63, there were peaks and valleys in the force curve representing the variations in resistance offered by the sand bond during scratching. In the experiment loose sand particles already removed also offers the resistance to the scratching and lifts the tip up. Whenever the surface is weaker, the tip goes deeper, and causes the variations. If examined for the forces during the experiment in high-pressure specimen, only one peak existed with more than 10 g magnitude and the average and standard deviation of the scratching force were 4.3 lg and 0.5lg, respectively. The same procedure and setting were followed to conduct the scratching test in aeration filled specimen, and the resulting scratching force plot is displayed in Figure 64. 176 Scratching Force Hot (Areation Specimen) a -5 Time (sec) Figure 64. Scratching Force Plot in Aeration Specimen with Vertical Load Upon the close examination of force plot, five peaks appeared higher that 10 g in this case. The average and standard deviation of scratching force were 5.0lg and 0.5g, respectively. By analyzing the data, it was evident that the average of 4.31 g of force was enough to break the bonds between the sand grains in high-pressure blow filled specimen, whereas 5.10 g force was required in aeration filled specimen. This observation suggested that the clay bond in aeration filled specimen was stronger with the homogeneously consistent bonding than high-pressure blow filled specimen. Further statistical analysis was done to investigate the significance. A two-sample t-test was conducted and result is shown in Table 32. Table 32. Comparison of Scratching Force in Aeration and High-pressure Samples Two-Sample T-Test and CI Sample N Mean StDev SE Mean Aeration 1950 5.01 0.50 0.057 High-pressure 1950 4.31 0.52 0.054 Difference = mu (Aeration) - mu (High-pressure) Estimate for difference: 0.7000 95% CI for difference: (0.5461, 0.8539) T-Test of difference = 0 (vs not =): T-Value = 8.92 P-Value = 0.000 DF = 3891 177 As shown in Table 32, p-value for t-test was zero, which rejected the null hypothesis of equal means of two filling techniques. Further, 95% confidence interval around zero for the difference in mean showed all positive values (0.5161, 0.8539). This concluded a significant difference in the samples of the two filling techniques with aeration on the higher side. Validation of the Findings From the experimentation and test result analysis, aeration appeared as a greener sand molding technique. It is an energy efficient technology with the capability of filling sand molds in any orientation. From the laboratory test, it was suggested that friability, a measure of the surface abrasive property of a sand mold, was lower in aeration than the conventional as-mulled sand. Friable mold is unable to hold the sand grains together, and the loose sand is easily washed away by the metal flow during metal pouring. In other words, a mold-wall having friable sand suffers more erosion loss when it comes into contact with the metal flow. As guided by this fact, it was anticipated that sand mold built in aeration should have less sand erosion, and castings produced in this mold were supposed to be free from erosion defects. Since aeration mold has lower friability than as- mulled gravity filled sand mold, it should have less erosion defects. This needs to be verified by examining the quality of the actual castings. This section is devoted to investigate the quality of the castings produced in different molding techniques. Test casting was required for the comparison because the available simulation software does not have the sophistication to simulate the mold metal interfaces. The test castings could provide information on casting surface quality, defect 178 tendencies, and effects of foundry processing variables - pouring temperature, head pressure, and metal velocity- on defect formation. Test casting quality was evaluated in terms of erosion resistance. Molding equipment, design of the test casting's pattern, test parameters, and methods of interpreting results are described in the following section. Molding and Green Sand Properties It was shown in the previous section that aeration technique could produce a mold at 30% compactibility levels with the benefits of lower friability and denser mold at laboratory conditions. This implies that aeration technology can produce molds at lower compactibility (lower moisture) levels compared to the conventional molding range of 35 - 40%. Sand filling was accomplished in less than O.lMPa gauge pressure in aeration, which is significantly less than the 0.6 MPa blow pressure used for high-pressure blow system. Any types of sand can be used with the identified aeration parameters to fill molds without regard to the inherent differences in flowability and shape of the grains. With the aeration sand filling system, it is possible to produce molds with enough strength and hardness while providing an even density distribution and integrity at the mold/metal interface. In this study the same aeration sand filling system described in chapter II was used. The flask was replaced with a new one having a matchplate pattern and an additional squeezing mechanism. This test machine is quarter the size of an actual molding machine with the flask size of 500 mm x 300 mm x 275 mm. In this machine, a nozzle for blowing the green sand is positioned on top of a built-in flask. Figure 65 shows the schematic diagram of the aeration sand filling system. 179 Green Sand Tank | Aeration Filter-, r.^v.%? WW Air Inlet | ) lft?#il Air Inlet Pressure Sensors- Air Inlet Air inlet Air Outlet' Nozzle Built-in Flask. Pattern \tw~\ Squeeze Plate Figure 65. Schematic of Aeration Sand Molding System As shown in Figure 65, match plate pattern with wedge design was mounted on the flask to create a mold cavity for the test casting. Vent holes were located at the top of the flask that allowed driving off the air and filling the mold densely. A data acquisition module connected to aeration system automatically records, displays and stores the information about the time, pressure and sequence of the aeration operations. Preparation of Green Sand to Desired Compactibilitv Green sand system also in this study consisted only of sand, clay, and water. As in the study of different sand systems presented in the earlier section, no additives were introduced into the green sand system, which kept the bonding formulation simple reduced the potential errors green sand preparation. The silica base aggregate (lake sand) 180 used in the study came from the shore of Lake Michigan, and its properties are shown in Table 33. In addition, this enabled the researcher to evaluate the performance of the green sand without additives. Table 33. Typical Properties of the Lake Sand Properties Values Screens 4 AFS-GFN 61.53 AFS Clay Content, % 0.34 LOI 0.25 Sub- Shape Rounded Roundness/Sphericity (Krumbein) 0.7/0.7 pH 7.5 Acid Demand Value (ADV, 7 pH) 1.40 Turbidity 28 M.Blue Clay, % (Total Clay 8% BOS) 7.45 Source Michigan If the green sand without additives is able produce the castings with no defects, use of the hazardous chemicals can be avoided in the green sand. The clay bond pre- blend contained 80% southern bentonite and 20% western bentonite, where total clay added was 8.0% BOS (methylene blue). Water was added to produce the desired compactibility and was monitored continuously. The water additions were raised or lowered accordingly, on each batch of sand to produce the 35% target compactibility. The sand was not discharged until the compactibility was on target. The green sand system used in the study was mulled at Western Michigan University, Sand Casting Laboratory. General procedures of green sand tests listed in chapter n of this dissertation were being followed. 181 Green Sand Properties Compactibility test, which is the most fundamental task in sand control, was administered to monitor sand temper. Lower the compactibility, higher the friability of a sand system. Defects related to the friable sand also called dry sand defects such as inclusions, erosion, cuts and washes were prevented in conventional molding systems by keeping high (35 - 44%) compactibility levels. Surprisingly, the aerated sands had shown that at lower compactibility levels (30%) there were no negative tradeoffs in sand friability. This fact is both beneficial and significant. Although aeration could produce mold at 30% compactibility level, 35% level of compactibility was chosen to compare the two techniques in this study. Since the molds that were gravity filled with as-mulled green sand were cracking and crumbling upon removing the matchplate pattern from the drag mold, it was not practical to produce the molds below a 35% compactibility level. Specimen weight of the silica sand was 158g and moisture content was 2.5%. Basic AFS green sand properties tests results of the silica sand from as-mulled and aerated systems are displayed in Table 34. Table 34. Properties of the Green Sand at 35% Compactibility Level Molding Techniques AFS Test As-mulled Aeration Compactibility (%) 35 (0.79) 35 (0.2) Bulk Density (g/cm3) 0.89 (0.01) 0.99 (0.01) Permeability (#) 233 (3.28) 222 (2.39) Green Compression Strength (psi) 24 (0.6) 24 (0.86) Mold Hardness (#) 94(0.8) 94(1.0) Friability (%) 17 (2.0) 7 (0.33) Note: number in parenthesis indicates standard deviations. 182 As shown in Table 34, at 35% compactibility level, green sand in aeration displayed 7% friability, which was within the 10% AFS limit, and was considerably less than 17% of as-mulled gravity filled mold. Bulk density was slightly higher in aeration, whereas remaining green sand properties: permeability, green compression strength and mold hardness were hardly showing any difference. Experimental Matchplate and Gating Design Design of the gating system was done in reference to the general guidelines for non- pressurized system with a gating ratio (Ac: AR: AG) of 1: 3: 3. Where, Ac, AR, and AG represents the cross sectional area (CSA) of choke, runner and gate respectively. Sand erosion erupts in a sand mold by a turbulent flow of liquid metal. Liquid metal flow velocity plays a decisive role to create the turbulence in the flow for a given gating design. Velocity of the liquid metal in a mold is primarily a function of the head height of the flow, gravity, and the frictional losses of the flow in the gating system. In a non- pressurized system with negligible frictional losses, velocity is expressed as: V = *j2gh Equation 51 Where, V= velocity of the liquid metal flow (m/sec), g = gravitational constant (9.8 m/sec2), and h = head height (m), i.e. distance between the parting line of the mold to the lip of the ladle from where metal is poured. Metal velocity of 1.5 m/sec with the presence of turbulence was recommended as a starting point to see the erosion on green sand mold (Showman, 2009); the pattern was designed accordingly, and metal casting flow and solidification simulation software 183 verified the gating design and flow velocity. Using Equation 51, when metal is poured at the top of the 75 mm sprue, the calculated velocity at the bottom of the sprue was to be 3.8 m/sec. Similarly, a 150 mm tall sprue would have the metal traveling at 5.4 m/sec at the bottom of the sprue. Solid model of the pattern, pictures of the experimental matchplate pattern, and simulation results are shown in Figure 66. (a) Pattern CAD Model (b) Pattern Plate (b) Velocity Profile (d) Pressure Profile Figure 66. Gating Design and Simulation Results 184 Figure 66 (c) and (d) represents the velocity and pressure profile of the liquid metal flow. The vertical rod represents the height of the sprue (head height). Simulation pictures of the velocity and pressure profile were ordered according to the filing sequence. Simulation pictures at the top represent the beginning and the bottom pictures represent the simulation near the end of the pouring process. Figure 66(c) showed the location of the turbulence occurred on the wedge section. For the short (75 mm) down sprue the simulation results indicated a maximum velocity of 1.8 m/sec and maximum pressure of 0.003 MPa with a metal splash indicating turbulence. For the tall (150 mm) down sprue the simulation results indicated a maximum velocity of 3.6 m/sec and maximum pressure of 0.003 MPa with the greater metal splashing indicating more turbulence. However, it must be noted that the simulation models used in this study do not predict erosion losses of the sand. After designing, the pattern and gating system were made out of wood and attached to the match plate. The match plate pattern was mounted on the flask. After setting up the match plate pattern and the flask, green sand was mulled and transferred into the aeration chamber for aeration molding, and directly to the flask for gravity fill. Air pressure applied in aeration was set at 0.07 MPa for 2.0 seconds, which allowed the mold/flask to completely fill with green sand. From the aeration pressure curve, it was observed that the transfer of the aerated green sand to the flask was completed within 1.0 second after the start of the pressurization. Uniform mold density in the flask/mold was achieved in the aeration sand filling. 185 After filling, the green sand mold was squeezed with a set pressure. The aeration system had a built-in squeezing mechanism with a hydraulic cylinder to squeeze the drag- half of the mold after filling. In case of the as mulled gravity mold, green sand at 35% compactibility was manually filled into the drag flask and squeezed with a hydraulic press. Reusable copes with a built-in pouring basin and a sprue were designed and developed to cap the drag molds as shown in Figure 67. Metal was melted in an induction furnace concurrently along with the mold preparation to avoid any delays and resulting process variations. Mold drying and metal over heating might have incurred due to longer waiting time. Drying causes higher erosion and overheating increases the penetration defects along with the erosion. (a) Schematic Diagram of the mold (b) Mold Figure 67. Test Flask with Cope and Drag Mold As shown in Figure 67, green sand was used to make the drag half of the mold. The wedge section was vertically below the pouring basin and a narrow channel supplied the 186 molten metal to the reservoir. Bottom of the pouring basin (sprue) was acting was a choke to regulate the metal flow. The wedge shape of the casting was designed to receive the direct impact (the pressure) of the metal flow and to provide an easy flushing of the eroded sand. The cope was designed on a single piece steel plate with ceramic lining underneath. Design of Experiments (DOE) In this experiment series of casting trials were carried out to compare the two sand molding processes using an experimental matchplate. Two molds were produced concurrently using the same heap of the green sand that was prepared at once. One mold was produced using aeration sand filling technology and the other was produced by as- mulled gravity filling. Two factors were varied in this experiment: mold squeeze pressure and head height. Mold squeeze pressure denotes the squeezing pressure used to compact the mold after sand filling. Head height was the height distance from the lip of the ladle to the parting line. Two levels of each factor were investigated. Levels of the squeeze pressure were determined from the existing squeezing pressure range used in industry: low (0.6 MPa) and high (0.8 MPa). Squeezing pressure more than 0.8 MPa was not recommended because extreme compaction of the mold makes it difficult to retract the pattern. Low squeeze pressure below 0.6 MPa could not compact the sand enough and the resulting molds lacked the strength to hold the shapes in the mold and might break during handling. Chances of penetration defects are higher in a less compacted mold. Levels of the head height: tall (150 mm) and short (75 mm) were calculated to achieve sufficient pressure head to impart an impact on the wedge surface and create turbulence in the 187 liquid metal flow. The lower head height was set to a level (75 mm) to exhibit less or no turbulence, whereas the higher head height (150 mm) was designed to create sufficient turbulence in the metal flow. Since the mold contained a single cavity with no core, there was no positional effect to be assessed on the casting. This approach allowed the possible variation in casting quality to be assigned to the molding techniques, either the aeration or the as-mulled gravity. A total of twelve pairs of molds were produced and poured. Molds were prepared and tested at Western Michigan University, Metal Casting Laboratory with the ambient conditions of 22±1°C temperature and 50±2 percent of relative humidity. The casting trial process flow is shown in Figure 68. As shown in Figure 68, the casting trial consisted of squeezing, pouring, finishing and inspection in addition to the sand preparation and filling procedures described in the chapter four of this dissertation. After molding drag half of the mold in green sand, a permanent copes was capped to the drag and the pouring basin was set on it. Metal (grey cast iron) was poured into the molds within ten minutes after the mold was ready. Molds were poured in a randomized order (aerated or as-mulled) manually through a pouring basin down the sprue, which determined the head height. Pouring time was recorded and controlled manually. The average pouring time was 8.0 seconds; temperature at pour was targeted at 1410°C (2,570 °F). Major alloying elements of the grey cast iron were: C = 3.55, Si =1.96. Detail metal chemistry is shown in Appendix P of this dissertation. Castings were allowed to air-cool and solidify at room temperature. After the complete solidification, castings were shaked- out, de-gated and cleaned with the low pressure (0.40 MPa) sand blasting. 188 35% Legend Operation (^ J) Inspection | | Transfer r—\ &osian Figure 68. Test Casting Process Flow Diagram 189 Measuring Erosion Depth After the finishing operations castings were inspected for the possible defects and surface quality. Inspection involved visual as well as non-contact digital methods on the wedge section of the castings. Erosion on the wedge surface of the casting was primarily studied, although some other minor cuts and washes were observed on some of the surfaces in visual inspection. Since wedge surface was receiving the direct impact of the metal flow with the highest velocity, it was a potential spot of erosion defects. Measurement of erosion losses using an ATOS II (Advanced Topometric Sensor) 3D coordinate measurement machine was conducted at Metrology Laboratory, Western Michigan University, which allowed the researchers to record the surface deviations from the pattern reference to the casting. He ATOS II system is shown in Figure 69. Figure 69. Non-contact Coordinate Measurement Machine 190 ATOS is an optical measuring device, which is based on the principle of triangulation. 3D coordinates for each point are calculated, and a polygon mesh of the object's surface is generated. Using the ATOS II system, objects can be measured with high accuracy (±10 um). ATOS consists of a head and a stand. A sensor is mounted on the head and connected to the computer through a cable. The measurement consists of projecting different fringe patterns onto the object's surface using a white light projection unit and capturing these patterns by two integrated cameras mounted at either side of the sensor head as shown in Figure 69. After each scan the measurement is displayed on the computer screen. Within seconds, the ATOS software has a capability to calculate the precise 3D coordinates of up to four million object points in each measurement. A series of scanning is required to get the complete shape. The coordinates of the new points after each scanning will accumulate and add on the data cluster. All measurements are automatically transformed into a common object coordinate system. The complete 3D data set can then be exported using standard file formats for an easy post-processing. This system monitors both its calibration and the influence of environmental conditions by itself, so that the measurement is reliable. Following steps involved while measuring the surface using ATOS E: • Positioning of sensor • Scanning • Measurement • Post processing 191 The ATOS II head was mounted on a stand and was positioned in front of the measuring object (pattern or casting). The object was placed on a table with the surface to be examined facing toward camera. Reference points were marked for the global coordinate system around the surface. The object was centered and kept within the view (bright region) of the camera. The object was secured on the scanning table and scanned at a different angle by slightly rotating (5-10 degree) it after each pass. This rotation provided an opportunity to disclose and map the missed points in the preceding scan. The wedge surface was reverse engineered into a CAD (Computer Aided Design) model using the coordinates of the surface scanned in ATOS H This model facilitated the researcher to analyze the surfaces and calculate the erosion depth by subtracting the pattern reference surface from the casting surface. Wedge surfaces of the castings and respective surface profiles are shown in Figure 70. The amounts of the surfaces deviations were displayed in a different color. All data was summarized in Tables 35 to facilitate the analysis. In Figure 70, first row of actual castings pictures were followed by the CAD model in the second row. Figure 70(b), was the complete casting with gating. Figure 70 (a) and (c) were the expanded view of the wedge surfaces of the casting produced in aeration and gravity filled molds. Casting produced in an as-mulled mold has extra deposition on the wedge surface. During pouring sand was eroded and washed away with the metal flow, cavity developed due to erosion was later filled with the metal and appear as a bulge when solidified. The uneven surface in the casting produced in an aeration mold was the roughness inherited by the sand casting process rather than the erosion. 192 a) Wedge Surface b) Test Castings c) Wedge Surface (Aeration) (Gravity) d) Aeration to Pattern e) Pattern Surface f) Gravity to Pattern Figure 70. Erosion on Wedge Surface of the Test Castings The sectional view of the wedge surface as shown in Figure 71 further clarified this fact. The location of the sand erosion and resulting metal deposition on the casting surface is shown in Figure 71. Figure 71 (a) was the sectional view of the green sand mold showing the sand erosion due to the impact of the molten metal. Figure 71(b) displayed an uneven surface build-up in the wedge section of the resulting casting 193 produced in gravity due to the sand erosion on the mold surface. The erosion losses of sand were accounted for the build-up and the over size of that part of the castings. A significant difference in erosion on castings was identified in the molds produced with different molding techniques. Sand erosion was lesser in the aeration molds than that of the as mulled gravity molds. Pattern Line *'i~"::£'%?i-'?: ...... &&'--&•&: : • -rf< * ../. • .M , * . ••••.» --F-" .,*.*'**,i >j^ .:--:. i*'*- "." •>»" ..;--"•; 1- — •» i ^3, 1""" '-, V- J- ."ji" «. C" .• >,> 4 -rf "•r- -.-, .?*. . J ":'r * '•"':--"'-.*•" -^*"*' -••-j-v'.--",-"""---'!- *c-'^i'i;"'^/::ii*«^&:-iv.:--; X (a) Erosion in the Green Sand Mold (b) Casting Surface Build-up Figure 71. Sand Erosion and Resulting Irregular Casting Section The average erosion depths of the various combinations of head height and squeeze pressure are summarized in Table 35. The difference or the depth of erosion was measured in millimeter. Table 35. Depth of Erosion in Different Sand Molding Techniques Depth of Erosion (mm) Squeeze Pressure Head Height Aeration Gravity (MPa) (mm) High (0.8) Short (75) 0.08 0.20 Tall (150) 0.13 0.32 Low (0.6) Short (75) 0.37 1.50 Tall (150) 0.83 2.60 194 Table 35 demonstrates the amount of erosion with the various combinations of head height and squeeze pressures in two molding techniques. Data suggested a different amount of erosion with the different levels of the factors. Erosion depth was high in as- mulled gravity filled molds under low squeeze pressure, especially in high head height. Further analysis of the data was performed using ANOVA. Statistical analysis of the data is presented in Table 36. Table 36. ANOVA: Erosion Depth versus Squeeze Pressure, Head Height, Techniques Factor Type Levels Values Squeeze Pressure (MPa) fixed 2 High, Low Head Height (mm) fixed 2 75, 150 Techniques fixed 2 Aeration, Gravity Analysis of Variance for Erosion Depth(mm) Source DF SS MS F P Squeeze Pressure (MPa) 1 10.4539 10.4539 1912.66 0.000 Head Height (mm) 1 1.4154 1.4154 258.96 0.000 Squeeze Pressure (MPa)* 1 0.9012 0.9012 164.88 0.000 Head Height (mm) Techniques 1 5.1120 5.1120 935.30 0.000 Squeeze Pressure (MPa)techniques 1 3.3218 3.3218 607.75 0.000 Head Height (mm)*Techniques 1 0.2228 0.2228 40.76 0.000 Squeeze Pressure (MPa)* 1 0.1288 0.1288 23.56 0.000 Head Height (mm)*Techniques Error 24 0.1312 0.0055 Total 31 21.6869 S = 0.0739299 R-Sq = 99.40% R-Sq(adj) = 99.22% As shown in Table 36, p-value for the interactions was zero, which was less than the standard significance level of 0.1. This suggested the presence of three way interactions among the factors: squeeze pressure, head height and techniques. The interactions are presented visually in Figure 72. 195 Data Means Hiph Low 75 150 Techniques / -•— Aeration • •- - Gravity Techniques H Squeeze Pressure (MPa) Squeeze Pressure (MPa High Low Head Height (mm) a) Interactions plot Surface Plot of Erosion Depth(mm) vs Technique, Squeeze Pressure(MPa) Erosion Depth(mm)' Squeeze Pressure(MPa) b) Surface plot Figure 72. Interaction Plot for Erosion Depth (mm) As shown in Figure 72, at high squeeze pressure, erosion in both techniques was seemingly equal, but when the squeeze pressure was lowered, the gravity filled mold 196 experienced larger erosion than the aeration mold. Opposite happened in head height. When head height was increased, erosion was increased in both molds although the rate was not the same. The gravity mold saw more erosion than the aeration mold. In low pressure squeezed mold when the head height was increased from short (75 mm) to tall (150 mm) the erosion depth was increased. Due to the interactions main affects of a single factor could not be interpreted and a Post-hoc analysis was conducted on the combination of the factors. Homogeneous sub sets from the post-hoc analysis is presented in Table 37. Combinations are ordered vertically in an ascending order according to the average erosion depth (smallest to largest). Table 37. Student-Newman-Keuls: Erosion Depth (mm) Subset Combination N 1 2 3 4 5 6 HAS 4 0.08 HAT 4 0.13 0.13 HGS 4 0.2 HGT 4 0.32 LAS 4 0.37 LAT 4 0.83 LGS 4 1.5 LGT 4 2.5 Sig. 0.398 0.193 0.348 1 1 1 Means for groups in homogeneous subsets are displayed based on observed means.The error term is Mean Square (Error) = .005. Uses Harmonic Mean Sample Size = 4.000.b. Alpha = .1. Where A = aeration, G = gravity, H = high squeeze pressure, L = low squeeze pressure, T = tall head height, S = short head height As shown in Table 37, the combinations were grouped into six homogeneous subsets. Upon examining the order, combinations with the low squeeze pressure were 197 positioned at the bottom. This suggested the fact that erosion was higher at low squeeze pressure irrespective to the techniques and head height. While examining the techniques within the low squeeze pressure combinations, gravity was below the aeration. This suggested that the gravity mold had the higher erosion than the aeration mold at lower squeeze pressure. For low squeeze pressure and gravity, the head height was aligned small to tall, and signified the higher erosion in tall. In other words, with tall head height and lower squeeze pressure, the as mulled gravity filled mold suffered the highest erosion. A similar trend of head height and technique was observed to the high pressure squeezed mold. The order was replicated with lowest erosion in aeration with short head height followed by tall head height. It could be suggested that aeration with high squeeze pressure and short head height could be the best combination to produce the molds with minimal erosion defects. As a conclusion, erosive flow of the liquid molten metal in this casting trial successfully compared the abrasion resistance property of the green sand mold built in different molding techniques. Lower squeeze pressure and higher head height were the critical levels of the factors that contributed to the green sand erosion. The potential for cuts and washes increased with the reduced squeeze pressure on the molds irrespective to the molding process. This would logically be attributed to the reduction in mold density. When head height (pressure) was reduced, the potential for cuts and wash was lower. The aeration filled molds were seen to have less erosion tendencies than that of gravity filled molds. This result verified the earlier findings of the laboratory tests. Green sand properties from these tests suggested less friability in the aeration molds. 198 This study revealed that lake sand system had superior erosion resistance in the aeration molding. It is plausible to suggest that the same should be true for the alternate sand systems since that was the case in the laboratory friability testing. However, additional green sand systems and other molding processes are recommended to compare. Friability is a measure of the abrasion resistance of a sand mold. Molds with friable green sand are not able to withstand the erosive flow of the molten metal. Molding sands can become very friable if there is a high influx of core sand, new sand, and bond. Friability of the working sand improves with an increase in its use. New bond requires several passes through the muller before its properties are developed. Since friability is inversely related to the compactibility, the lower the compactibility, the higher the friability. A drop in compactibility, or a brief air-drying; will produce an increase in friability. The rate of increase in friability is not the same for all compatibility levels. The rate is higher at lower compactibility levels (< 40%). Sand erosion at the mold wall is directly related with friability. The higher friability molds develop more erosion losses. Erosion produced the casting defects in two folds: at the point of erosion and at the point of sand deposition. At the point of erosion, molten metal eroded the sand from the mold surface, and enlarged the mold cavity producing oversized castings. On the other hand, the eroded sand streaming with the liquid metal became lodged into the pattern cavity, and produces inclusion defects. In other words, in a friable mold, surface erosion defects were developed at the point of erosion, and the consequent inclusion defects at the point of deposition. 199 Conclusion and Recommendations From the series of experiments and analyses of AFS green sand test results in comparing aeration with conventional filling techniques, aeration appeared as a superior sand filling technique. Most of the properties of aerated green sand were similar to that of conventional gravity and high-pressure blow. Although the main effects of the aeration factor were not evident separately, its impact on green sand properties appeared as an interaction effect in combination with sand and compactibility. Friability appeared lower in aeration than in conventional methods. This established the fact that fluidization and low pressure sand filling process in aeration was modifying the green sand properties advantageously, which interacts interestingly with sand and compactibility levels and generates some unique response in green property. Friability normally increases while drying green sand by air, but in this case, air was passed through the sand mix, but friability was decreased. Obviously, during aeration process, the green sand was experiencing some sort of drying phenomenon and part of it might hurt the friability, but other actions were also happening, which nullified that effect and gave a net benefit of lower friability. This finding was able to address the concerns of the researchers and sand casting experts about the increasing trend of friability in foundries. It was reported that friability in the foundries is increasing with the use of high-speed production lines (Heine & Mcintosh, 2001). Researchers are trying different ways to lower the friability. Various chemicals and compositions of clay were tried, but the problem was persistent, and the issue is being compromised as a business trade-off with the productivity. This study demonstrated that filling techniques could contribute to green sand properties; aeration 200 has the ability to reduce the friability. The fluidization and low pressure sand filling in aeration successfully improved some of the green sand properties and provided a new direction in sand control research. In addition, test results revealed that aeration molding did not discriminate between the density differences of the sands. This molding technique successfully filled the sands with a wide variety of densities from regular silica to relatively heavier specialty chromite sand. Experimental results also revealed that the aeration technique filled the flask with sand grains of different shapes, and it did not discriminate among the sand systems. For example, round grain ceramic media, angular grain chromite as well as sub angular olivine were effectively filled irrespective to their grain shape. This implied that aeration possibly allowed a wider range of sand types in molding. Aeration enhances the sand flow into the mold and facilitates the filling of small sections. Sand flow in aeration was smoother with higher flowability and was able to fill small pockets (sleeve) and deep holes (tubes) effectively with consistent density distribution. The AFS tubes, which were oriented horizontally into the flask, were equally filled. The aeration technique opened the new horizon for the sand casting research to design and produce the castings with near-net shape with better flowability, higher and uniform density distribution, along with the capability of filling molds in any orientation. The near-net shape castings are closer to the actual product dimension and save the secondary finishing operations. This was not possible with the traditional molding techniques. In addition, low-pressure air was used in aeration; the mold was successfully filled with the air pressure of O.lMPa in 2 seconds. Aeration requires less energy in comparison to conventional high-pressure blow system, which required tremendous power in compressing the high-pressure air (0.3-0.5MPa. 201 Another objective of this dissertation was to find the optimal working range for aeration molding technique in order to realize aforementioned benefits with better casting quality. As cited in the literature review section of this dissertation, mold quality is the function of materials, operating parameters, and environmental factors. Impacts of these parameters were quantified by different green sand properties tests as prescribed by AFS. Permeability, green compressive strength (GCS), mold hardness, bulk density and friability are the major AFS tests followed in the foundries. This research revealed that permeability was more dependent upon the sand type. For example, chromite possessed high permeability number, which was around 300, whereas olivine had hardly 80. There was a smaller impact on permeability by a change in compactibility level. Mold hardness is more related with the squeezing technique rather than the filling technique. In all combinations mold hardness numbers were in or above 90. On the other hand, green compressive strength was in the range of 20 to 30 lbs/in2 with a small change induced by the aeration. This showed that most of these green properties did not undergo much change and remained within the workable range mentioned in conventional molding literatures. The only green property that changed with compactibility and was critical in mold quality was friability. As a best practice established by AFS, friability above 10% is not desirable, and friability is inversely associated with compactibility. To cope with the situation of maintaining 10% friability limit, foundries are using higher levels of compactibility (40%) in the existing molding techniques. Since this study showed that in aeration the friability was below 10% even at 30% compactibility, it is now possible to work at lower than the existing compactibility levels. Thus, the optimal working range for aeration is set to 30% compactibility level, 0.1 MPa air pressure and 2 sec filling time. In addition, aeration seemed less susceptible to the compactibility. The change in friability 202 when compactibility was changed from 40% to 30% was only 3.4% in average where as the same change was more than 14% in gravity. This is a favorable facet for sand control in foundries because, contrary to the traditional methods, minute change in compactibility does effect too much in green sand properties, and the sand system remains more stable with lesser variations. Aeration is more robust with compactibility; in other words, a wider range of compactibility will afford quality mold using aeration. This might be of interest for molding process engineers. Friability testing proved to be more sensitive in its capability of discriminating minute changes in sand clay interactions than other AFS tests. This test appeared to have greater potential in sand control with the possibility of providing a baseline to estimate other green sand properties. It was evident that a relationship between friability and other green sand properties exists. Based on these relationships, a range of other green sand properties could be estimated, which may help to reduce or eliminate the requirements of all currently standard test and/or their frequencies in sand control. Dynamic test development and its use in aeration was another objective of this dissertation. The existing cone jolt, a dynamic toughness tester, was improved with the use of automation and data storage capability, and a thermal erosion tester was designed and used to investigate the sand clay behavior at elevated temperature. Cone jolt test measured the toughness of the green sand, which detected the changes in clay composition precisely. The specimen was tested under the cyclic impulses provided by lifting and dropping the base plate. Number of jolts (#) before failure gave an idea about the toughness of the mold. Different sand systems were investigated in advanced cone jolt tester. Numbers of jolts before failure for sand system with different clay compositions were significantly different. Since the number of jolts before failure of the aeration sand 203 specimen was not significant with that of gravity, aeration did not hurt the toughness of the green sand. Thermal erosion tester on the other hand, displayed a significant difference in sand erosion between the gravity and aeration filled specimens. A typical scenario of common head height and flow velocity was used along with the heated element temperature of 700°C. Applicability and relevance of the advance cone jolt test might be in the domain of assessing clay composition change and detecting contaminants in the sand system. On the other hand, the thermal erosion tester finds its niche in its ability to precisely depict the mold metal interface and effectively assesses the impact of molten metal in sand clay interaction. In the green property test, it was evident that the fluidization process was causing some changes in sand-clay relationship in a sand system. Study of the sand clay interactions was performed by X-ray diffraction, which provided better insight to understand and explain the material behavior under aeration. X-ray diffraction pattern showed that, in aeration, clay platelets were non-directional and isotropically distributed throughout the sand-clay mix, coating the sand grains equally. This resulted in a smooth and consistent bonding between the sand grains. Thus, a mold built by aeration filling technique got better erosion resistance. This showed the action of the fluidization. In addition to drying, there was an extra mulling happening in micro-scale, which distributed the clay particles. Further, clay coating in sand grains was investigated microscopically using Scanning Electron Microscope (SEM).The green sand sample of the aeration molding had smoother clay coating than that of the high-pressure blow sample. Another contribution of this research was identifying newer sophisticated techniques to assess the green sand property precisely. Universal Micro-tribometer (UTM), which is widely used in the tribology studies of the materials, was employed to 204 measure the bonding strength of the mold surface. It precisely measured the grain-to grain bonding strength in a short time. The UMT test showed the better surface property with higher bonding strength in aeration samples. Sand samples from aeration needed more scratching force to knock the sand particles apart. This result supported the lower friability in aeration, a test result shown in a conventional foundry test, and concluded that the better bonding of sand grains was imparted by aeration and consistently induced higher bonding strength in the mold surface. Higher surface bonding strength provided lower friability and better erosion resistance. Producing a test casting validated laboratory green test results. Metal was poured in the molds produced in two molding techniques. Molds were squeezed with two levels of pressure and metal was poured from two head heights to investigate their respective impact on erosion. Molds produced with high squeeze pressure gave less erosion defects. In addition, erosion was always higher in the as mulled gravity molds than the aerated molds for given squeeze pressure and head height. It was also observed in laboratory test that aeration had less friability than gravity molds. The test casting findings supported the results of the friability test that green sand having higher friability produces more erosion defects. It also provided a rationale to predict the erosion resistance ability of a mold by a laboratory test. The erosive flow of the liquid metal produces an erosion defect in a mold having higher friability. In summary, aeration appeared superior to conventional mold filling technique with its capability in producing complex shapes and deep pockets with low friability. Fluidization mechanism interacted with sand and compactibility, and altered the sand- clay relationships. Friability among AFS green property test appeared more sensitive in detecting the changes in compactibility and molding techniques. Relevant green sand 205 properties were studied under various situations from laboratory tests to a test casting production, and it was concluded that friability and erosion resistance of the green sand mold were improved in aeration. Lower level of compactibility, which is below the existing common compactibility level in foundries, was recommended as an optimal working range for aeration. X-ray diffraction and SEM helped to identify the cause of lower friability in aeration. Universal micro-tribometer appeared to be a better research tool in green sand study. Dynamic tests helped to better understand the dynamic behavior of the green sand system and will be beneficial in sand control to identify the variations systematically, which are currently treated as random. Benefits of Aeration Mixing Aeration provides the extra mixing of the green sand. Air passing through a micro- porous media mechanically blends the mixture by dispersing the water and clay throughout the sand. Thorough mixing converts the water and clay into bonding entities that are uniformly distributed over the sand grain surface. Mixing and/or mulling by air in aeration introduces the mechanical impingement between the sand grains and transfers the excessive coating from one grain to another, and develop an essentially uniform clay coating. Mulling force causes kneading and smearing as well as compression and shearing. In conventional mulling, a muller consists of plow and wheels, which plows continuously, and compresses and decompresses the green sand by its wheel faces. Similar types of compressive and decompressive action happen during aeration by the random fluffs of the sand mass by the air. Because of the larger volume of the sand batch, mixture and muller has some limitations in distributing clay and water uniformly. On the 206 other hand, aeration agitates the green sand and fluidizes with the air supplied uniformly from all sides of the fluidizing chamber, and eliminates any gross lumps coming from the muller. Aeration fluffs minimizes super-voids on the sand mass and produces a uniform density throughout the mold. The action of fluidization in aeration remains equally effective in all types of sand grains. Normally, an angular grain, having a higher surface area requires more bonding material, and their interlocking nature resists to compaction. The sub angular is better for foundry use, requires less binder, and compacts to the higher density. Rounded grains require least bond, and are compacted to the highest density. Compounded grain, which is the agglomerates of small grains bonded together to form a larger grain, is not usually recommended for foundry use. Their bond generally is not strong enough to keep grain integrity during mold filling, transport, casting, and shakeout. When the sand grains break down, they generate excessive fines, lowering permeability. In all sand systems aeration increases the bonding effectiveness of the green sand by enhancing the clay coating to the sand grains. Limitations and Recommendations for Future Study This research was conducted in a laboratory environment, which is an ideal condition in regards to the production floor. Room temperature and relative humidity were controlled, and the test was conducted immediately after molding, which might not be the case in a production floor. Extra precaution was taken to prevent the moisture loss from the green sand samples by sealing the containers. Practically, it is almost impossible to maintain the temperature and relative humidity to a desired level in a production floor. In addition to the operating parameters, weather conditions, and time of the day could alter 207 these environmental parameters. In the initial phase of this research, molten metal was not poured into the mold, and the change in green properties after metal pouring was not included. While comparing the green sand properties, four replications were made as a laboratory molding, which might be a small sample for the study of a production molding. Larger number of replications is recommended in the future study to compare the molding techniques in the production environment. In addition, various parameters of the green sand such as GFN, sieve distribution, and clay content were assumed constant in this study. A comprehensive future study of the green sand properties varying all these parameters could help to better understand the sand control in aeration. Sand-clay behavior of the green sand were analyzed to study the impact of different molding techniques, SEM and x-ray diffraction suggested the random distribution of clay platelets, giving more consistent homogeneous mix in aeration. Aeration process fundamentally consists of two stages: fluidization and low pressure filling. In fluidization, sand was fluffed with low pressure air and mixed, and during filling sand was driven to a mold by creating a directional flow by the low pressure air. Samples for the analyses were taken after the completion of the aeration filling process, and it is not clear whether the fluidization or low pressure air stream or both induced the effect of better surface abrasive property in green sand. Study of the sand-clay interactions within the different stages of the aeration process is recommended for future research. Friability provided a measure to estimate other green sand properties for olivine sand system as shown in Figure 73. 208 Friability vs. Green Sand Properties 180 3.5 • Permeability A Bulk density (Ib/cu ft) OGCS(psi) • Compactibifity(%) + 2.5 • Moisture(%) c a o Q t 1-5 £ o 4- 0.5 15 20 Friabity(%) Figure 73. Friability versus Green Sand Properties of Olivine Sand in Aeration As shown in Figure 73, for a measured value (10%) of friability level, other green sand properties such as GCS (30 psi) and bulk density (65 lbs/ft3) could be estimated from the graph. Similar type of graphs for other green sand systems could also be developed and used to estimate their respective green sand properties. Dynamic tests are essential to reliably monitor and control the green properties of the sand system in foundries. Advance cone jolt and thermal erosion tester had provided good insight about the importance of dynamic test and their relevance in detecting the 209 minor changes precisely in a sand system. These tests procedures require further improvement and testing. The casting trial represents one green sand system as an example of the application with aeration sand filling and casting. Specialty sand, alternative molding media, and reclaimed sands were not considered in this study. There are numerous other green sand systems, not to mention the systems containing additives from which casting trials on the aeration mold need to be analyzed. The scope of this research was constrained to establish the general trends for aeration molding and casting quality. A broader analysis of the molding and casting is recommended to future study. Table 38. Summary of the Research Findings a) Main Effects in Green Sand Properties Properties Main Factors Order Remarks Friability Compactibility 40, 35, 30 Clay swelling at higher (Lower) compactibility provides better Technique Aeration, anchoring of sand grains. Aeration Gravity enhances clay coating on sand grains, and reduces friability. Permeability Sand Chromite, Angular sands have greater recess (Higher) Compactibility & Olivine between the grains. Interaction Greater swelling of clay in higher compactibility enlarges the recess. GCS Sand Angular shape grains interlock (Higher) Sand *c ompactibility better enhance bonding strength. Mold Sand Lower the compactibility denser the Hardness Compactibility & mold, and harder the mold surface (Higher) Interaction with higher mold hardness number. Bulk Sand Chromite Heavier sand gives higher density, Density 30,35,40 Greater swelling at higher (Higher) Compactibility Aeration, compactibility lowers bulk density. Technique Gravity Aeration with extra mixing distributes clay uniformly, and breaks lumps and clay balls giving higher bulk density. 210 Table 38 - Continued b) Material Characterization Methods Findings X-ray Diffraction Random orientation of clay platelets developed homogeneous mix in aeration samples Scanning Electron Smooth clay coating on aeration sample at micro-scale Microscope Micro-tribometer Higher bonding strength between sand grains and clay at mold surface in aeration c) Dynamic Sand Test Dynamic Sand Test Green Sand Factors Remarks Property Advance Cone Jolt Toughness Drop height, Identify changes in a clay (# of jolts) RPM composition & contaminants Thermal Erosion Erosion on mold Speed, Aeration has low erosion surfaces at 700 °c Head pressure d) Comparison of Molding Techniques Features Aeration High- pressure blow Gravity Filling process Fluidization, directional Blast filling Gravitational flow Power require Less High Minimal or no (low- pressure<0.1MPa) (Pressure>0.5MPa) Manual & Sophistication Automated & complicated Automated & simple complicated Benefits / Cost High Low Low Friability Low (<10%) High (>10%) High (>10%) Near net shape Possible Not possible Not possible Filling Any direction possible Not possible Not possible orientation Mold Density Uniform distribution Non-uniform Non-uniform Erosion (mm) Low (0.03-0.8mm) High High (0.2-2.6) Compactibility Low (30-35%) High (35 - 40%) High (35 -40%) Note: Features ol ? high-pressure blow and gravit y filling techniques wer e in accordance to the existing literature. 211 REFERENCES American Foundrymen's Society (AFS) (2000). Mold & core test handbook. (3rd. ed.). Bailey, R. (1983). Quality through testing part 1. Modern Casting, 73, 19-22. Bakhtiyarov, S. I., Overfelt, R.A. & Reddy ,S. (1996). Study of the apparent viscosity of fluidized sand. American Society of Mechanical Engineers, Applied Mechanics Division, 217, 243-249. Bakhtiyarov, S. I., Overfelt, R. A. (1996). Study of cohesive flow in fluidized foundry sands. Transactions of the American Foundrymen's Society, 104, 705-708. Bakhtiyarov, S. I., Overfelt, R.A. (1996b). Study of channeling phenomena in fluidized foundry sands. American Society of Mechanical Engineers, Heat Transfer Division, 323, 239-245. Bex, T. (1992). Green sand molding at forefront of productivity gains. Transactions of the American Foundrymen's Society, 100, 102-105. Boenisch, D. (1988). New concepts of green sand technology - part ii. Foundry Management Technology, 116,38-49. Bralower, P. M. & Granlund, M. J. (1989). Controlling properties of molding sands. Modern Casting, 79(4), 51-54. Callister, W. D. J. (2007). Materials science and engineering an introduction (7th ed.). NY: Jhon Wiley and sons Inc. CETR (2008). Solutions for tribology research. Retrieved Sept. 21, 2008, from http://www.cetr.com/en/services/research.html. 212 Dietert, H. W., Graham A. L., & Schumacher J. S. (1974). Sand control program that saves castings. Transactions of the American Foundrymen's Society, 82, 329-342. Graham, A. L., Praski, R. M., & Edwards, D. H. (1979). Measuring friability of molding sands with present sand testing equipment. Transactions of the American Foundrymen's Society, 87, 453-458. Heine, R. W., & Mcintosh, M. A. (2001). Friability of green sand. Transactions of the American Foundrymen's Society, 105, 907-910. Heine, R. W., Schumacher J., & Green R. (1977). Sand/Metal ratio and moisture content for cooling of green sand. Transactions of the American Foundrymen's Society, 84, 281-286. Hicks, C.R., Turner, K.V. (1999) Fundamental Concepts in the design of Experiments (5th ed.). N Y: Oxford University Press, Inc. Hirata, M. (2002). Eco-conscious molding system, featuring aeration sand filling, preset squeeze and mold height feedback control. Transactions of the American Foundrymen's Society, 110, 697-704. Hirata, M., & Sugita, K. (2005). New sand filling method in flaskless molding and its controls. Transactions of the American Foundrymen's Society, 113, 319 - 326. Knight, D. F. (1973). Sand control system for high-pressure molding. The Foundry Trade Journal, 134, 10-14. Krysiak, M. B. (1994). Reducing casting defects: A basic green sand control program, Part 1. Modern Casting, 84(4), 35-38. Krysiak, M. B. (1994). Reducing casting defects: A basic green sand control program, part 2. Modern Casting, 84(5), 39-42. 213 Krysiak, M. B., & Pedicini, L. J. (1990). Sand handling systems affect castings produced in green sand- successful sand testing design, part 1. Modern Casting, 80(2), 44-46. Krysiak, M. B., & Pedicini, L. J. (1990). Sand handling systems affect castings produced in green sand- successful sand testing design, part 2. Modern Casting, 80(3), 42-44. Krysiak, M. B., & Pedicini, L. J. (1990). Sand testing design, part 3. Modern Casting, 80(4), 39-41. Krysiak. M.B., Ramrattan, S.N., & Cheah S.F. (2002). Thermal distortion of green sand and chemically bonded sand at cast iron fill temperatures. Transactions of the American Foundrymen's Society, 110, 651-664. Kunii, D., & Levenspiel, O. (1991). Fluidization engineering. Butterworth-Heinemann: Elsevier. Kuz'min, N. N. (1987). Clay science. Aurora: Clay Minerals Society. LaFay, V. (2009). Advancing eco-friendly binders. Modern Casting, 99(10), 35-36. LaFay, V. S., & Krysiak, M. B. (2008). pH of green sand: Past, present, and future. Transactions of the American Foundrymen's Society, 116, 329-346. Levelink, H. G., VandenBerg, H., & Frank, E. (1973). Sand quality in modern molding lines. Transactions of the American Foundrymen's Society, 81, 129-134. Loto, C. A., & Adebayo, H. (1990). Effects of variation in water content, clay fraction and sodium carbonate additions on the synthetic molding properties of igbokoda clay and silica sand. Applied Clay Science, 5(2), 165-181. Makino, H. (2008). Friability test by using FBOX. [Unpublished raw data]. Makino, H., Hirata, M., & Hadano, Y. (2003). Computer simulation and optimization of sand filling using the distinct element method. [Personal interview]. 214 McClune W. F. (2001). ICDD powder diffraction file. International Center for Diffraction Data, Newtown Square, Pennsylvania. Morgan, J. H. (1973). Some problems of sand preparation. The Foundry Trade Journal, 135, 675. Philips, D. R. (1970). Sand control by independent variables. Transactions of the American Foundrymen's Society, 78, 52-258. Radhakrishnan, A. (1975). Physical properties of bentonite-bonded molding sand. The Foundry Trade Journal, 139, 95-99. Ramrattan, S. N. (2008), Sand molding techniques. [Personal interview]. Ramrattan, S. N., Paudel, A. M, Makino, H., & Hirata, M. (2008). Desirable green sand properties via aeration sand filling. Transactions of the American Foundrymen's Society, 116,493-503. Rhodes, M. (1998). Introduction to particle technology. New York: Wiley. Rhodes, M. (2001). Relevant powder and particle properties. Retrieved Apr. 15, 2008, from http://www.erpt.org/012Q/rhod-02.html. Ricardo, J. (1980). Understanding green sand: A review. Modern Casting, 70(1), 39-43. Roshan, H. M. (1975). Temper point of molding sands. The Foundry Trade Journal, 139, 33-34. Sanders, C. A., Doleman, R.L. (1970). Bonding clay technology, current concepts, Transactions of the American Foundrymen's Society, 78, 57-65. Schleg, F. P. (2003). Technology of metal casting, Chicago: American Foundrymen's Society. Schumacher, J. S. (1983). Problem of hot molding sands - 1958 revisited. Transactions of the American Foundrymen's Society, 91, 879-888. 215 Showman, R. (2009). Turbulence in sand mold. [Personal interview]. Somers, R. W., & Melcher, R. E. (1972). A new dimension in green molding sand for the nonferrous foundry. Transactions of the American Foundrymen's Society, 80, 51-60. Speakman, S. A. (2008). The wonders of X-ray diffraction. Retrieved Sept.2, 2008, from http://prism.mit.edu/xray. Tordoff, W. L. & Tenaglia, R. D. (1980). Test Casting Evaluation of Chemical Binder Systems. Transactions of the American Foundrymen's Society, 88, 149-158. Wyoming Rails (2005). Retrieved Apr. 15, 2008, from http://www.trainweb.org/wyomingrails/wymining/wybentonite.html. Capture 3D (2006). ATOSII User Manual, V6. Retrieved Nov. 15, 2009, from http://www.gom.com. 216 APPENDIX A Data Collection Tables Table 1. Data Collection Sheet Experiment No: Environmental Room conditions Filling Testing Date: Temperature i Sand Type: R. Humidity ! Aeration flow Gravity Test 1 JL...... 3 ! .1. .J -2. ...i A.. ! 1 \ Aeration Pressure i i i [Mpa] _ i I .__! 2 1 i Moisture Content • 1 .,.[%] _.„ ._._. __ J 1 ! 3 i Bulk Density ; ! i i [gm/cc] ; ! \ ; _ j ! 4 J Mold Hardness i ! [BHN]L J __._J 5 > Compatibility(3-Ram) ! _[%]__ _. __,.___ J i i • 1 Compatibility(Sqz) f 6 i ! [%] ; ! : „„j ! ! Green Sand Strength i 7 i [psi] ! ! i __ J i i 8 : 1 Split Strength 1 t Ipsi] .__ _.. ; _ _j i i 9 | Permeability ' i ! i ! i 10 MQI 1 ': i i 11 ! Elec. Permeability 1 : ! 12 Friability (%) ' I i . 217 Boxplot of Green Sand Properties 400- * 300- 1 o Magnitud e 100- Xlvv * 0- m 1 , , , , . —i— ^ 2t S\ # ^f .^ # # s? r& jf *? J? * ~ON f o° S ^Nr Figure 1. Green Sand Properties Ranges in Foundries Table 3. Green Sand Properties of Olivine Sand in As mulled Gravity: Initial study Moisture Compactibility Bulk density Permeability GCS Friability (%) (%) (ft/cu ft) (#) (psi) (%) 1.3 11 90.1 35 12.5 81 1.8 17 83.2 50 22.5 46.8 1.9 19 81.25 59 25.03 40.6 2 21 76.46 68 27.83 32.6 2.1 24 72.52 78 31.82 22.3 2.2 27 70.95 89 35.2 20 2.3 30 67.14 98 35.79 13.9 2.4 33 63.2 110 34.94 12.6 2.5 36 59.72 120 30.4 10.2 2.6 40 56.39 126 27.2 8.1 2.7 46 50.24 140 20.41 5.7 2.8 53 45 160 14.02 2.5 2.9 58.5 40.62 180 10.02 2 218 Table 4. Green Sand Properties of Olivine Sand in Aeration: Initial study Compactibility Moisture Bulk density Permeability GCS Friabil (%) (%) (lb/cu ft) (#) (psi) (%) 11 1.3 98.1 36 14.5 51 17 1.8 85.2 51 21.5 33.5 19 1.9 82.25 59 25.5 30.26 21 2 78.46 67 27.98 25.6 24 2.1 74.52 80 32.56 18.3 27 2.2 72.95 85 36.22 12.5 30 2.3 69.14 95 35.79 9.58 33 2.4 66.2 104 34.94 9.23 36 2.5 60.72 112 30.24 8.2 40 2.6 57.39 124 25.2 5.3 46 2.7 50.54 136 22.54 3.2 58.5 2.9 40.62 170 12.66 1.2 219 APPENDIX B Material Data Sheet of Various Sands Chromites Minerals Percentage Si02 1.34 MgO 8.75 Cr203 45.80 A1203 21.34 Fe203 19.50 CaO 0.94 TiQ2 0.03 Montmorillonite Na (OH)4 AI4 Si8O20. NH20 Ca (OH)8 Al4 Si8O20. NH20 220 APPENDIX C Experimental Data Table 1. Experimental Data: Green Sand Properties Bulk Mold Moisture Permeability GCS Friability Sand Technique Compatibility Density Content Hardness (#) (psi) (%) (g/cm3) (%) m Lake 30 0.990 2 220 19 98 9.5 Aeration 30 0.980 2.1 220 20.7 96 9.3 30 0.990 1.9 221 19.6 99 7.5 30 1.010 2 219 20 99 10.2 35 0.970 2.2 225 25.2 94 7 35 0.980 2.3 224 24.5 95 7.3 35 0.971 2.2 226 25.2 95 6.9 35 0.960 2.5 225 25.1 95 6.9 40 0.930 2.5 229 20.5 92 5.5 40 0.940 2.6 228 21.2 93 4.5 40 0.940 2.5 230 20.36 93 4.9 40 0.920 2.4 234 21.9 92 5.5 Gravity 30 0.970 1.9 228 21.1 96 32 30 0.987 2.2 226 21.15 96 33 30 0.980 1.9 229 21.55 97 33 30 0.990 1.9 228 21.05 97 26 35 0.900 2.5 232 24.5 94 15 35 0.910 2.5 234 23.25 93 14 35 0.920 2.5 233 24.5 92 17 35 0.930 2.5 232 24.3 93 18 40 0.880 2.6 260 24.25 92 9.5 40 0.890 2.7 259 24 91 10.1 40 0.880 2.7 261 23.95 92 8.5 40 0.830 2.5 262 24 93 11.5 RG Aeration 30 1.150 2 182 22.5 98 9.5 30 1.170 2.1 186 21.5 99 9.1 30 1.120 1.9 185 20 96 9 30 1.200 2 184 21.9 99 10.2 35 1.100 2.2 193 25.3 94 7 35 1.120 2.3 189 24.5 92 7.3 35 1.130 2.1 190 25.2 90 7.9 35 1.080 2.3 190 26.1 94 7.9 40 1.030 2.4 195 23 89 6.5 221 GO 03 1 3 Q. 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MUMCOU^OlslCOCDlD OlO)slffl(OM0000(Ogg(D oo -»• o O(00oocnaiuui0)0i(os (D £2. CO W en O) •vl (O oo oo 00-vl00_i.(O(O(O_i. en -*1 01 ~s| co L Ob fO co '->• bo o o -* f° -•• -^ -* -* ro ro oo oo ligiliO^liLiQ) 05 K) •v2i oi en -p>. cn co oo o ->• L L M 01« ^ « en io ^ co ai 00 en co o> en co co oo j^ oo ai ro i\) 35°.o>ocMa)a>o- CO CO o oiioajoiniocoso't^io NScocoinio'2ioSt*in o v- 0)0)0)0)0)0)0)000)0)0) 00)0)0)0)0)0)0)0)0)0)0) 000000g>0g"000 X ") O m in m lO i- o o co K- -*t O) O) CM c/>~ O O . . . O CD OJ o in oo CM co in ^ - m in in co O « 5 S "? °! "! °! 5? « «H iri •* oo co • n W (M S N .^. rv. -r^ co q co CM Si ^ CM' O i- o O) oi co co C^O *-C?O CO CO CM CM CM co co co CO CO CM CM CM CM CM CM S CM CM r-. in CM CO CO •-B CM CM CM 1O) , O u, CL, co-^ cDOji-oooocMcnoo-r-t-m OCOCOCMCMCOCMCOCOCMCOO (0!0^T-SCO(OCOI-*O)O 00 10 •* •* co O) CM CM |-~- l~- 1^. CDC M O CM^CM^^ "™ CM CM CM CM i- co co •* in o o^- CM CM CM N CM CM CM CM CM CM CM CM CM CM CM CM CMC M CM CM CM CM CMC M CM CM CM CM CMC\ i CO is cs Q ooo)oo^i-i^-omioo)T-o OOOOOOOOOOOO oi s in ID o co ^ o i— oo co o T- T- oo in i- o ^'3 w E T-cDcooi-cMOT-coinin- x pq oooomminmoooo o co 3"- ooooinwwmoooo cocococococococO' CD 'c x: o i CD I I CD o c E CO o i. 2 "8 .c O O Table 1. Experimental Data: Green Sand Properties Sand Technique Compatibility ^ Moisture Re ^S JjgJ^ Friability (%) (g/cm3) (%) (#) (PSI) (#) (%) 30 1.170 2.3 224 26.79 102 15.2 30 1.170 2.2 227 27.5 99 15.5 30 1.170 2.2 222 25 101 17 35 1.100 2.3 242 29.42 99 8.6 35 1.140 2.3 242 32.21 100 11.5 35 1.150 2.3 248 31.95 100 11.6 35 1.150 2.3 246 30.9 99 12.2 40 1.000 2.5 265 28.56 97 7.4 40 0.990 2.4 268 27.89 96 10.6 40 1.000 2.4 270 27.1 96 8.4 40 1.000 2.5 265 27.7 97 9.8 Table 2. ANOVA: Permeability versus Sand, Technique, Compactibility Factor Type Levels Values Sand fixed 5 Ceramic Media, Choromite, Lake, Olivine, RG Technique fixed 2 Aeration, Gravity Compactibility fixed 3 30, 35, 40 Analysis of Variance for Permeability Source DF SS MS F P Sand 4 943190 235798 21782..6 8 0..00 0 Technique 1 1027 1027 94..8 4 0..00 0 Compactibility 2 11740 5870 542..2 7 0,.00 0 Sand*Technique 4 12170 3042 281,.0 6 0..00 0 Technique*Compactibility 2 1075 538 49..6 6 0..00 0 Sand*Compactibility 8 1181 148 13..6 4 0..00 0 Sand*Technique*Compactibility 8 573 72 6,.6 2 0,.00 0 Error 90 974 11 Total 119 971930 S = 3.29014 R-Sq = 99.90% R-Sq(adj) = 99 .87% 224 Table 3. ANOVA: GCS versus Sand, Technique, Compactibility Factor Type Levels Values Sand fixed 5 Ceramic Media, Chromite,, Lake, Olivine, RG Technique fixed 2 Aeration, Gravity Compactibility fixed 3 30, 35, 40 Analysis of Variance for GCS Source DF SS US F P Sand 4 1699.773 424.943 180.78 0.000 Technique 1 2.369 2.369 1.01 0.318 Compactibility 2 64.747 32.374 13.77 0.000 S and*Te chni que 4 39.641 9.910 4.22 0.004 Sand*Compactibi1ity 8 297.272 37.159 15.81 0.000 Technique*Compactibi1ity 2 12.858 6.429 2.73 0.070 S and*Te chni que * C omp ac tib i1i ty 8 96.881 12.110 5.15 0.000 Error 90 211.559 2.351 Total 119 2425.100 S = 1.53319 R-Sq = 91.28% R-Sq(adj) = 88. 47% Table 4. ANOVA: Mold Hardness versus Sand, Technique Factor Type Levels Values Sand fixed 5 Ceramic Media , Chromite, Lake, Olivine, RG Technique fixed 2 Aeration, Gravity Compactibility fixed 3 30, 35, 40 Analysis of Variance for Hold Hardness Source DF SS HS F P Sand 4 184.217 46.054 24.91 0.000 Technique 1 0.300 0.300 0.16 0.688 Compactibility 2 142.813 71.406 38.63 0.000 Sand*Technique 4 95.617 23.904 12.93 0.000 Sand*Compactibility 8 229.208 28.651 15.50 0.000 Technique*Compactibility 2 12.262 6.131 3.32 0.04l| Sand*Technique*Compactibility 8 143.008 17.876 9.67 0.000 Error 90 166.375 1.849 Total 119 973.800 S = 1.35964 R-Sq = 82.91% R-Sq(adj) = 77 .41% 225 Table 5. ANOVA: Bulk Density versus Sand, Technique Factor Type Levels Values Sand fixed 5 Ceramic Media, Chromite, Lake,, 01ivine , RG Technique fixed 2 Aeration, Gravity Compactibility (%) fixed 3 30, 35, 40 Analysis of Variance for Bulk Density (g/cm3) Source DF SS MS F P Sand 4 2.158219 0.539555 1930..3 7 0..00 0 Technique 1 0.036925 0.036925 132..1 1 0..00 0 Compactibility (%) 2 0.400140 0.200070 715,.7 9 0..00 0 Sand*Technique 4 0.007905 0.001976 7..0 7 0,.00 0 Sand*Compactibility (%) 8 0.034577 0.004322 15..4 6 0..00 0 Technique*Compactibility (%) 2 0.001938 0.000969 3..4 7 0..03 5 Sand*Technique*Compactibility (%) 8 0.017426 0.002178 7..7 9 0..00 0 Error 90 0.025156 0.000280 Total 119 2.682286 H = 0io0167185 K-Hw = 99io06% K--HM($BO) = 98K>76 g. 226 APPENDIX D Post-hoc Duncan Test Results Table 1. Post - hoc Duncan Test Results: GCS Subset Data 1 2 3 4 5 6 7 8 9 10 11 12 13 14 LA30 19.13 RG35 20.56 20.56 LG30 21.21 21.21 RA30 21.48 21.48 21.48 RG30 22.30 22.30 22.30 22.30 RG40 22.43 22.43 22.43 22.43 RA35 22.85 22.85 22.85 RA40 23.35 23.35 23.35 LA40 23.90 23.90 LG40 24.05 24.05 LA35 24.08 24.08 LG35 24.14 24.14 CG40 25.16 25.16 CA40 26.25 26.25 MA40 26.26 26.26 MG30 26.27 26.27 MG40 27.81 27.81 CG35 28.03 28.03 OA40 29.25 29.25 OG30 29.69 29.69 29.69 MA35 30.02 30.02 30.02 MG35 30.87 30.87 30.87 CA35 31.09 31.09 31.09 MA30 31.35 31.35 31.35 OA35 31.69 31.69 31.69 OA30 31.86 31.86 CG30 31.97 31.97 OG40 31.99 31.99 CA30 33.21 OG35 35.0 Sig. .19 .13 .18 .13 .15 .15 .36 .15 .12 .13 .11 .13 .14 1.00 The error term is Mean Square (Error) = 2.351. First letter and second letters represents sand type, and technique, respectively, numeral at the end is compactibility level. L = Lake sand, R = Round Grain, 0 = Olivine, M = Ceramic Media, C = Chromite, A = Aeration, G = Gravity, 227 00 CO en en r- CN cn CN CN •8 u CN 0, CN 3 CO CN •§ co CO 4) W CN t IT M» 00 N (S N N N c CN tN CN CN CN 3 in rj- in Q CN CN CN o CN CN CN o CN .£5 O O CN (X N tf •* 0\ C\ ON 8 IT) 00 I CM 100 oo oo o tl ON O a r- oo s oH r- § ON NO ^cn ^^•^•'^•^^•^•^•^•'t-*^,*'«trrTl--rJ-^l-^-rf'*Tt^-^rj--5t- oo>noingooioioooo>n2Soo>o!S!C32o2o>riooino i s 228 Table 3. Post -hoc Duncan Test Results: Permeability Data N Subset 1 2 3 4 5 6 7 8 9 10 11 12 13 14 RG30 4 89.3 RA30 4 89.5 LG30 4 92.8 LA30 4 93.0 LG35 4 93.0 RA35 4 93.0 OG35 4 93.3 93.3 OG30 4 93.5 93.5 93.5 OA40 4 94.0 94.0 94.0 94.0 MA30 4 94.1 94.1 94.1 94.1 94.1 LA35 4 94.5 94.5 94.5 94.5 94.5 RG35 4 94.5 94.5 94.5 94.5 94.5 CA40 4 95.0 95.0 95.0 95.0 95.0 CG30 4 95.0 95.0 95.0 95.0 95.0 CA35 4 95.3 95.3 95.3 95.3 MA35 4 95.4 95.4 95.4 95.4 CG40 4 95.5 95.5 95.5 95.5 CG35 4 95.8 95.8 95.8 95.8 95.8 LG40 4 96.0 96.0 96.0 96.0 MG35 4 96.5 96.5 96.5 96.5 CA30 4 96.8 96.8 96.8 96.8 96.8 RG40 4 96.8 96.8 96.8 96.8 96.8 MA40 4 97.3 97.3 97.3 97.3 LA40 4 97.5 97.5 97.5 97.5 OA35 4 98.0 98.0 98.0 98.0 OG40 4 98.0 98.0 98.0 98.0 RA40 4 98.5 98.5 98.5 98.5 OA30 4 99.3 99.3 99.3 MG30 4 99.8 99.8 MG40 4 100 Sig. .80 .13 .13 .10 .13 .11 .13 .12 .12 .19 .12 .11 .11 .16 .80 The error term is Mean Square(Error) = 1.849. First letter and second letters represents sand type, and technique, respectively, numeral at the end is compactibility level. L = Lake sand, R = Round Grain, O = Olivine, M = Ceramic Media, C = Chromite, A = Aeration, G = Gravity, 229 Table 4. Post -hoc Duncan Test Results: Friability Subset Data N 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 LA40 4 5.0 CA40 4 5.2 OA40 4 5.7 5.7 MA40 4 6.4 6.4 6.4 LA35 4 7.0 7.0 7.0 CG40 4 7.2 7.2 7.2 RA40 4 7.4 7.4 7.4 7.4 RA35 4 7.5 7.5 7.5 MA35 4 7.9 7.9 7.9 7.9 OA35 4 8.0 8.0 8.0 8.0 8.0 CA35 4 8.2 8.2 8.2 8.2 8.2 OG40 4 8.2 8.2 8.2 8.2 8.2 OA30 4 9.0 9.0 9.0 9.0 9.0 MG40 4 9.1 9.1 9.1 9.1 9.1 LA30 4 9.1 9.1 9.1 9.1 9.1 CA30 4 9.3 9.3 9.3 9.3 9.3 RA30 4 9.5 9.5 9.5 9.5 9.5 OG35 4 9.5 9.5 9.5 9.5 9.5 MA30 4 9.8 9.8 9.8 9.8 LG40 4 9.9 9.9 9.9 RG40 4 10.2 10.2 MG35 4 11.0 CG35 4 11.1 RG35 4 14.0 MG30 4 15.6 LG35 4 16.0 16.0 OG30 4 17.3 CG30 4 21.9 RG30 4 29.5 LG30 4 31.0 Sig. .18 .10 .12 .25 .11 .15 .11 .13 .28 .11 1.00 .62 .17 1.00 .10 The error term is Mean Square (Error) = 1.666. First letter and second letters represents sand type, and technique, respectively, numeral at the end is compactibility level. L = Lake sand, R = Round Grain, O = Olivine, M = Ceramic Media, C = Chromite, A = Aeration, G = Gravity, 230 Percent Percent Frequency Frequency vO. H- *- .3 —1 1— -4. 5 -1—! !- -J--I—i- - J 5. „ -•1—•!—• •• «i i i i 1 1 ! o i ; ; I 1 --.> -_.*. ;. 1 i : i ! -3. 0 -1. 5 \H 1- i 1 -2. 5 ! 1 i n» i -&4 i 1 -(---t- Resid u JO -]-V-i- : I • sid u o a 0. 0 » .I...J... o i^L ; 1 i or ,.L1V ! 1 XI i 1 cr h L1 ' a> !1° a 1 ! ll w II. \ . : ! i i ;~ 70 —T^ -i-i-~i- V~"i" a << a \ i i i ! . 5 3. 0 NJ i i ; e 2. u 1 : i Ul ---,-•-1-- -!'• -rlr O 5" a. i ; i 1 1 c •o i S < o •r-%k > 1 • SL 1 1 : i a> f tji (A a to o" m (A O Residual Residual Z Residual Residual us ro o N ^ •f V. Cu tn '». X <0. ai <&. •6. a •i> *. 3 O A % V (A or .<- < High-pressure Blow Systems Verification Data Date 5/21/2008 Temperature = 73F Relative Humidity = 47% Compactibility = 38% Sp. Wt.= 162 0.05 MPa 0.3 MPa Sample Initial Final Friability Initial Final Friability 1 324.60 274.70 15.37 323.00 276.90 14.27 2 325.40 280.70 13.74 325.90 284.10 12.83 3 325.00 279.50 14.00 325.20 283.30 12.88 4 324.00 275.40 15.00 324.50 278.50 14.18 5 324.90 275.10 15.33 324.60 284.30 12.42 6 325.10 281.90 13.29 325.80 278.40 14.55 7 325.60 279.80 14.07 329.40 279.50 15.15 8 324.00 275.80 14.88 325.70 282.30 13.33 AVE 14.46 13.70 Stdev 0.79 0.97 t-test p-value= 0.11 No si gnificant difference 232 APPENDIX G X-ray Diffractometer Setting and Results Parameters Values Company Diano (Rating 50 kV 30mA) Model 780 Voltage (Kv) 40 Current (Ma) 20 Power (Watt) 800 Target Cu Filter Ni 2T 20-110 Time step (sec) 0.02 Delta E 9.0 Spin On CTHV-1 1200 Eh 9.3 EI 0.3 Beam Width (inch) 1.56 X-ray Diffraction Pattern of Silica Sand • £jj PDF # 882302, Wavetengtt( = 1.54060 (A) 1 88-2302 QuateC Si 02 CAS Number: Silicon Oxide Molecular Weight: 60.08 Ref: Calculated from ICSD using P0WD-12+* Volume[CD]: 112.93 Ret: Will, G„ Bellotto, M„ Parrish. W.. Hart, M., J. Awl Qvstatogf.,21,182(1988 1 Die 2.650 DOT Sys: Hexagonal Lattice: Primitive •S.G.: P3221 (154) Cell Parameters: a 4.912 b c 5.403 iT oo I l_kJ 1 1 1 28' l/lcor: 3.09 0 l'5 30 45 60 75 Rad: CuKal Lambda: 1.540G0 28 Int-f h k I 2a Int-f h k i 26 Int-f h k 1 Filter: 201864 213 10 0 55.342 15 0 1 3 77.692 12 2 2 0 d-SD: calculated 26,646 999* 0 1 1 57247 2 2 10 73.306 24 2 1 3 ICSDtt: 041414 36.554 66 1 1 0 59.975 79 1 2 1 80.065 14 2 2 1 Mineral Name: 33.478 67 1 0 2 64.053 15 1 1 3 81.196 20 1 1 4 Quartz 40.302 30 1 1 1 65.803 4 3 0 0 81.512 25 3 1 0 42.462 50 2 0 0 67.762 49 1 2 2 83.860 15 1 3 1 45.807 27 2 0 1 68.163 60 2 0 3 84.981 2 2 0 4 501153 112 112 68,332 62 0 3 1 87.099 12 2 2 50:636 4 0 0 3 73.499 19 1 0 4 87.471 2 3 0 3 54,883 33 0 2 2 75.681 23 30 2 233 APENDEX H Scratching Force i-pressure Specimen Time F Time F Time F Time F Time F Time F_ 0.5 0.8 23.7 3.9 46.9 0.1 70.1 2 93.3 4.6 116 4.7 1 0.9 24.2 4 47.4 0 70.6 2.1 93.8 4.2 117 4.9 1.5 1.1 24.7 4.1 47.9 0.3 71.1 2.3 94.3 2.1 117 5.1 2 1.3 25.2 4.2 48.4 0.9 71.6 2.4 94.8 2.3 118 5.3 2.5 1.4 25.7 4.2 48.9 1.2 72.1 2.6 95.3 2.5 119 5.5 3 1.6 26.2 4.3 49.4 1.4 72.6 2.7 95.8 2.4 119 5.6 3.5 1.8 26.7 4.3 49.9 1.5 73.1 2.9 96.3 2.4 120 5.8 4 2 27.2 4.3 50.4 1.7 73.6 3.1 96.8 2.6 120 6 4.5 2.2 27.7 4.4 50.9 1.8 74.1 3.2 97.3 2.4 121 6.2 5 2.4 28.2 4.4 51.4 2 74.6 3.4 97.8 2.2 121 6.4 5.5 2.5 28.7 4.4 51.9 2.2 75.1 3.6 98.3 2.4 122 6.6 6 2.7 29.2 4.5 52.4 2.3 75.6 3.7 98.8 2.6 122 6.8 6.6 2.9 29.7 4.5 52.9 2.4 76.1 3.9 99.3 2.8 123 6.9 7.1 3 30.2 4.5 53.4 2.6 76.6 4.1 99.8 3 123 7.1 7.6 3.2 30.7 4.6 53.9 2.7 77.1 4.3 100 3.2 124 7.3 8.1 3.4 31.3 4.6 54.4 2.8 77.6 4.4 101 3.2 124 7.4 8.6 3.6 31.8 4.7 54.9 2.8 78.1 4.6 101 2.5 125 7.6 9.1 3.7 32.3 4.7 55.4 2.8 78.6 4.8 102 1 125 7.7 9.6 3.9 32.8 4.7 56 1.4 79.1 5 102 0.7 126 7.9 10.1 4 33.3 4.7 56.5 0.4 79.6 5.1 103 0.9 126 8 10.6 4.2 33.8 4.7 57 0.2 80.1 5.3 103 1.1 127 8 11.1 4.3 34.3 4.7 57.5 0.1 80.7 5.4 104 1.2 127 8.1 11.6 4.4 34.8 4.8 58 0.2 81.2 5.6 104 1.3 128 8.2 12.1 4.4 35.3 4.8 58.5 0.3 81.7 5.8 105 0.5 128 8.3 12.6 2.1 35.8 4.8 59 0.5 82.2 5.8 105 0.4 129 8.4 13.1 0.9 36.3 4.8 59.5 0.6 82.7 5.9 106 0.6 129 8.4 13.6 1.1 36.8 4.8 60 0.7 83.2 6 106 0.8 130 8.4 14.1 1.3 37.3 4.7 60.5 0.9 83.7 6.1 107 1 130 8.3 14.6 1.5 37.8 4.7 61 1 84.2 6.3 107 1.2 131 7.6 15.1 1.7 38.3 4.7 61.5 1.2 84.7 6.5 108 1.4 131 7 15.6 1.9 38.8 4.6 62 1.4 85.2 6.5 108 1.6 132 7.1 16.1 2 39.3 4.6 62.5 1.5 85.7 4.8 109 1.8 132 7.3 16.6 2.2 39.8 4.6 63 1.7 86.2 3.3 109 1.9 133 7.5 17.1 2.4 40.3 4.5 63.5 1.8 86.7 3.2 110 2.1 17.6 2.5 40.8 4.4 64 1.8 87.2 3.3 110 2.3 133 7.7 18.1 2.6 41.3 4.3 64.5 1.9 87.7 3.2 111 2.5 134 7.2 18.7 2.7 41.8 4.2 65 2.1 88.2 3.3 111 2.7 134 4.7 19.2 2.9 42.3 4.1 65.5 2.2 88.7 3.4 112 2.9 135 1.7 19.7 3 42.8 4 66 2.3 89.2 3.6 112 3.1 135 1.6 20.2 3.1 43.3 3.8 66.5 2.3 89.7 3.7 113 3.3 136 1.8 20.7 3.2 43.9 3.8 67 2.4 90.2 3.9 113 3.5 136 2 21.2 3.3 44.4 3.5 67.5 2.5 90.7 4 114 3.7 137 2.2 21.7 3.4 44.9 3.2 68 1.8 91.2 4.2 114 3.9 137 2.4 22.2 3.6 45.4 2.7 68.6 1.6 91.7 4.4 115 4.1 138 2.6 22.7 3.7 45.9 0.9 69.1 1.7 92.2 4.4 115 4.3 138 2.7 23.2 3.8 46.4 0.3 69.6 1.8 92.7 4.5 116 4.5 139 2.9 234 , rtPjtnifiiqhooMooojo Nm^" o\oo^-iNNtoni-'*inirnovot^t^oo«io\o\OOrt-iNNm(nTtTtinin>oioi~-M!Oi»o>o>oo-HrtMNm(r|Ttininio«i^t~- r-0000000000000000000000000000000000000000O\O\0\<^O\ON0\0\0S0\<^0\0\0\0\0\0\0\0s0sOOOOOOOOOOOOOOO •* IT) VO t--; fcl i/-> iri i/-> ir> '^^lNton^•'J»^u^^o^o^-^ooo!lo^o^oo-<' r^vqvqvor^r^r^voir)fntsr^<^c^rnrn^^Tj;Tj;^^^Tt^ir)in\q ooovoooo oo a\ -< M n 7f m « co eo co ci co co •* ^ Tt Tt Tt" Tf | i,inin«voh^ooooo\o\oO'H tO't'i•lnlA fl>o^-^ooooo^o^oo-^'HNNmn'!^•'*lnlnvo^o^^ooooo^o^oO'^'^Mnm'* •*'*'*',*-*Ti--^-Ti-'*'>*Tj-ininin MNN(SNNMN(SN(SNMN r^ooooo\f-\qinvi ^in«t^ooi^«Tt^>oi^Ttiot^O;(SMm^*qoqo\*>coo» ^H^H_,^Hoof~r-t--r--t-~r-r--t--p~ cococococococococ vovor-r-oooooNON Jr^ooo\0\0\>H>HNTtTtinin««i~;oooot^'0«inTt r~r~r-^r~r^ O6o6o6o6o6o6o6ooo6o6o6o6o6o6o6o6t^i ^ooooo^o\oOrtHN^lnm't'!tlnln^D^o^^ool»o^o^o-^'^^lM(nmTfTflnln^c>o^•^ooooo^o^oo•H-^^l^lnm^•i•lnu^ rt . rtcoinr^ON^coint^o\cs-*vqt--:ON'-;coinr~oo N^*oooo\rtmTt>ooo -HMTt COCOCO'-H'-HOOO Pooooo^' — ^^^cNcNcNcscscncnccicncn H Time F Time F Time F Time F Time F Time F 308 7.8 336 1.7 364 3.9 392 8.2 420 8.2 448 8.4 308 7.4 336 2 364 3.8 393 8.4 420 8.3 448 8.4 309 7.6 337 2.2 365 3.8 393 8.5 421 8.4 449 8.5 309 7.8 337 2.4 365 3.8 394 8.7 421 8.5 449 8.6 310 7.9 338 2.6 366 3.7 394 8.8 422 8.5 450 8.7 310 8.1 338 2.7 367 3.7 395 8.9 422 8.6 450 8.8 311 8.3 339 2.9 367 3.7 395 9 423 8.7 451 9 311 8.5 339 3.1 368 3.7 396 9.2 423 8.8 451 9.1 312 8.7 340 3.3 368 3.7 396 9.2 424 8.9 452 8.7 312 8.9 340 3.4 369 3.7 397 8.4 424 8.9 452 5.5 313 9 341 3.6 369 3.8 397 3.6 425 9 453 3.7 313 9.2 341 3.7 370 3.9 398 3.8 425 9.1 453 3.2 314 9.4 342 3.9 370 4 398 4 426 9.2 454 3 314 9.6 342 4 371 4.1 399 4.2 426 9.3 454 3.1 315 9.8 343 4.2 371 4.2 399 4.4 427 9.1 455 3.1 315 9.9 343 4.3 372 4.2 400 4.6 427 8.9 455 3.2 316 10.1 344 4.4 372 4.1 400 4.8 428 8.8 456 3.3 316 10.2 344 4.4 373 3.8 401 5 429 8.9 456 3.1 317 10.4 345 4.5 373 2.9 401 5.2 429 8.7 457 3.1 317 10.6 345 4.6 374 2.9 402 5.3 430 8.5 457 3.3 318 10.8 346 4.8 374 3.1 430 8.5 458 3.4 318 10.9 346 4.9 375 3.2 402 5.5 431 8.6 458 3.5 319 11.1 347 5 375 3.4 403 5.7 431 8.7 459 3.6 319 11.2 347 5 376 3.5 403 5.9 432 8.8 459 3.5 320 11.4 348 5.1 376 3.6 404 6.1 432 8.9 460 2.4 320 11.5 348 5.1 377 3.7 404 6.3 433 9 460 0.4 321 11.5 349 5.1 377 3.7 405 6.5 433 9.1 461 0.7 321 11.5 349 5.2 378 3.9 405 6.6 434 9.2 461 1 322 11.5 350 5.3 378 4 406 6.8 434 9.2 462 1.2 322 11.2 350 5.4 379 4.2 406 7 435 9.3 462 1.3 323 9.8 351 5.4 379 4.1 407 7.2 435 9.3 463 1.5 323 7.8 351 5.3 380 4.1 407 7.4 436 9.3 463 1.6 324 7.9 352 5.3 380 4.2 408 7.6 436 9.2 464 1.7 324 8 352 5.3 381 4.4 408 7.8 437 9 464 1.9 325 8.2 353 5.3 381 4.5 409 7.9 437 8.4 465 2 325 6.2 353 5.3 382 4.7 409 8.1 438 8.3 465 2.1 326 5.7 354 5.3 382 4.9 410 8.2 438 8.4 466 2.1 326 6 354 5.2 383 5 410 8.4 439 8.6 466 2.1 327 6.2 355 5.1 383 5.2 411 8.6 439 8.7 467 1.8 327 6.4 355 5.1 384 5.4 411 8.8 440 8.8 467 1.7 328 6.6 356 5.1 384 5.5 412 8.9 440 8.7 468 1.9 328 6.8 356 5.1 385 5.6 412 8.7 441 8.5 468 2.1 329 6.9 357 5 385 5.8 413 6.8 441 8.5 469 1.9 329 7.1 357 5 386 5.9 413 6.3 442 8.6 469 1.9 330 7.3 358 5 386 6.1 414 6.5 442 8.7 470 2 330 7.5 358 5 387 6.3 414 6.6 443 8.8 470 2.2 331 7.6 359 5 387 6.5 415 6.8 443 8.9 471 2.2 331 7.8 359 5 388 6.6 415 7 444 9 471 2.3 332 8 360 5 388 6.8 416 7.2 444 9.1 472 2.4 332 8.1 360 4.9 389 7 416 7.3 445 9.2 472 2.4 333 8.3 361 4.6 389 7.2 417 7.5 445 8.8 473 2.4 333 8.5 361 4.4 390 7.3 417 7.6 446 8.5 473 2.3 334 5.5 362 4.3 390 7.5 418 7.8 446 8.4 474 2 334 -0.2 362 4.1 391 7.7 418 7.9 474 2.1 335 0.7 363 4 391 7.8 419 8 447 8.5 475 2.3 335 1.3 363 3.9 392 8 419 8.1 447 8.5 475 1.7 236 Time F Time F Time F Time F Time F Time F_ 476 0.3 504 0.2 531 4.6 559 2.9 586 3.9 614 3.9 476 0.5 504 -0.3 532 4.7 559 2.8 587 4 615 4 477 0.6 505 -0.3 532 4.8 560 2.8 587 4.2 615 4.1 477 0.7 505 0 533 4.8 560 2.7 588 4.3 616 4.3 478 0.9 506 0.2 533 4.8 561 2.7 588 4.5 616 4.4 478 1 506 0.4 534 4.8 561 2.6 589 4.6 617 4.6 479 1.1 507 0.6 534 4.8 562 1.7 589 4.8 617 4.7 479 1.1 507 0.7 535 4.8 562 1.5 590 4.9 618 2.8 480 0.8 508 0.8 563 1.7 590 5.1 618 2.9 480 -0.5 508 0.9 535 4.8 563 1.8 591 5.2 619 3.1 481 -0.8 509 1.1 536 4.9 564 1.9 591 5.3 619 3.3 481 -0.9 509 1.2 536 5 564 2 592 5.3 620 3.5 482 -0.8 510 1.3 537 5.1 565 2.1 592 5.4 620 3.7 482 -0.6 510 1.4 537 5 565 2.2 593 5.4 621 3.8 483 -0.5 511 1.5 538 4.9 566 2.2 593 4.3 621 4 483 -0.4 511 1.7 538 4.7 566 2.3 594 4.2 622 4.1 484 -0.3 512 1.8 539 4.6 567 2.5 594 4.3 622 4.1 484 -0.2 512 1.9 539 4.5 567 2.6 595 4.4 623 3.1 485 -0.1 513 2.1 540 3.8 568 2.7 595 4.3 623 3.3 485 -0.1 540 3.8 568 2.8 596 4.5 624 3.5 486 -0.2 513 2.2 541 3.9 569 2.9 596 4.2 486 -0.3 514 2.3 541 4 569 3.1 597 4 624 3.7 487 -0.3 514 2.4 542 4.2 570 3.2 597 4.2 625 3.8 487 -0.3 515 2.4 542 4.2 570 3.3 598 4.3 625 3.9 488 -0.2 515 2.4 543 4.2 571 3.5 598 4.5 626 4 488 -0.2 516 2.5 543 4.3 571 3.6 599 4.2 626 4.1 489 -0.2 516 2.7 544 4.3 572 3.8 599 1.9 627 4.2 489 -0.3 517 2.8 544 4.3 572 3.9 600 2.1 627 4.3 490 -0.4 517 3 545 4.4 573 4 600 2.3 628 4.3 491 -0.3 518 3.1 545 4.3 573 4.1 601 2.5 628 4.4 518 3.2 546 4.3 574 4.3 601 2.7 629 4.1 491 -0.2 519 3.3 546 4.2 574 4.4 629 4 492 -0.1 519 3.4 547 4.3 575 4.5 602 2.9 630 4 492 0 520 3.5 547 4.2 575 4.7 602 3.1 630 4.1 493 0.2 520 3.6 548 4.1 576 4.8 603 3.3 631 4.1 493 0.3 521 3.7 548 4.1 576 4.6 603 3.4 631 4.1 494 0.3 521 3.8 549 4.2 577 4.2 604 3.5 632 4.2 494 0.3 522 3.9 549 4.2 577 4.2 604 3.7 632 4.2 495 0.3 522 4 550 4.2 578 4.2 605 3.8 633 4.2 495 -0.9 523 4 550 4.2 578 4.2 605 3.9 633 4 496 -0.9 523 4.2 551 4.2 579 4.3 606 3.9 634 1.7 496 -2.1 524 4.3 551 4.2 579 4.3 606 4 634 2 497 -2.7 524 4.4 552 4.1 607 4.2 635 2.3 497 -2.7 525 4.4 553 3.8 580 4.1 607 4.2 635 2.5 498 -2 525 4.4 553 3.7 580 3.9 608 4 636 2.7 498 -1.3 526 4.3 554 3.7 581 3.8 608 4 636 2.9 499 -0.8 526 4.4 554 3.7 581 3.1 609 4 637 3.1 499 -0.6 527 4.4 555 3.8 582 2.9 609 4.2 637 3.3 500 -0.6 527 4.5 555 3.6 582 3 610 4.4 638 3.5 500 -0.4 528 4.6 556 3.5 583 3.2 610 4 638 3.6 501 -0.2 528 4.6 556 3.5 583 3.3 611 2.7 639 3.8 501 0 529 4.6 557 3.5 584 3.4 611 2.9 639 3.9 502 0.1 529 4.7 557 3.5 584 3.4 612 3.1 640 4.1 502 0.2 530 4.5 585 3.5 612 3.3 640 4.2 503 0.4 530 4.4 558 3.1 585 3.6 613 3.5 641 4.4 503 0.6 531 4.5 558 2.9 586 3.8 614 3.7 641 4.5 237 Time F_ Time F Time F_ Time F Time F Time F_ 642 4.6 669 0.8 697 0.8 724 4.4 752 3.9 779 3.4 642 4.7 669 0.8 697 1 725 4.5 753 4 780 3.4 643 4.8 670 0.9 698 1.1 725 4.7 753 4.2 780 3.3 643 5 670 0.9 698 1.3 726 4.7 754 4.3 781 3.2 644 5.1 671 1 699 1.4 726 4.8 754 4.4 781 2.7 644 5.1 671 1 699 1.6 727 4.8 755 4.5 782 2.3 645 5.3 672 1 700 1.7 727 4.9 755 4.7 782 2.3 645 5.3 672 1.1 700 1.8 728 4.9 756 4.8 783 2.5 646 5.5 673 1.1 701 1.8 728 5 756 4.9 783 2.5 673 1.1 701 1.8 729 4.8 757 5 784 2.6 646 5.6 674 1.2 702 1.8 729 4.8 784 2.3 647 5.7 674 1.2 702 1.9 730 4.9 757 5.1 785 2.4 647 3.8 675 1.3 703 1.9 730 5 758 5.3 785 2.4 648 3.4 676 1.3 703 2.1 731 5.1 758 5.4 786 2.4 648 3.7 676 1.3 704 2.2 731 5.2 759 4 786 2.3 649 3.9 677 1.4 704 2.4 732 5.1 759 2.8 787 2.4 649 4.1 677 1.3 705 2.5 732 5 760 3 787 2.5 650 4.3 678 1.1 705 2.6 733 4.8 760 3.1 788 2.5 650 4.3 678 0.5 706 2.8 733 4.6 761 3.3 788 2.6 651 0.4 679 0.5 706 2.9 734 4.3 761 3.5 789 2.7 651 -0.3 679 0.7 707 3 734 4.3 762 3.7 789 2.8 652 -0.1 680 0.8 707 3.2 762 3.8 790 2 652 0 680 1 708 3.3 735 4.3 763 4 790 1.7 653 0 681 1.2 708 3.4 735 4.2 763 4.2 791 1.8 653 0 681 1.4 709 3.5 736 4.2 764 4.3 791 2 654 0 682 1.6 709 3.6 736 4.2 764 4.5 792 2.1 654 0.1 682 1.7 710 3.7 737 4.1 765 4.6 792 2.3 655 0.2 683 1.9 710 3.9 738 4 765 4.8 793 2.4 655 0.3 683 2.1 711 4 738 3.9 766 4.9 793 2.6 656 0.3 684 2.1 711 4.1 739 3.9 766 5 794 2.7 656 0.3 684 1.4 712 4.2 739 3.9 767 5 794 2.9 657 0.3 685 1.6 712 4.2 740 4 767 4.9 795 3 657 0.3 685 1.8 740 4 768 4.9 795 3.2 658 0.4 686 1.9 713 4.3 741 4.2 768 4.9 796 3.3 658 0.5 686 2.1 713 4.3 741 4.3 769 4.9 796 3.5 659 0.6 687 2.3 714 4.4 742 4.3 769 5 797 3.6 659 0.7 687 2.4 714 4.5 742 4.4 770 5.1 797 3.8 660 0.3 688 2.5 715 4.6 743 3.9 770 5.2 798 3.9 660 0.2 688 2.7 715 4.7 743 4.1 771 5.2 798 4.1 661 0.2 689 2.8 716 4.8 744 4.2 771 5.3 799 4.2 661 0.2 689 2.9 716 4.8 744 4.3 772 5.1 800 4.4 662 0.2 690 3.1 717 4.7 745 4.4 772 5 800 4.6 662 0.3 690 3.2 717 4.3 745 4.6 773 5.2 801 4.7 663 0.4 718 4.2 746 4.7 773 5.3 801 4.9 663 0.4 691 3.4 718 4.1 746 4.8 774 5.1 664 0.5 691 3.5 719 4.1 747 4.9 774 4.2 802 5 664 0.5 692 3.6 719 4.1 747 4.9 775 4 802 5.2 665 0.5 692 3.7 720 4.1 748 5 775 3.1 803 5.4 665 0.6 693 3.9 720 4.1 748 5.1 776 3.2 803 5.5 666 0.7 693 4 721 4.1 749 5.3 776 3.3 804 5.7 666 0.7 694 0.9 721 4.1 749 5.4 777 3.4 804 5.8 667 0.7 694 -0.1 722 4.1 750 5.5 777 3.5 805 6 667 0.7 695 0.2 722 4.2 750 5.6 778 3.5 805 6.2 668 0.8 695 0.3 723 4.2 751 5.6 778 3.3 806 6.3 696 0.5 723 4.2 751 5.6 779 3.3 806 6.5 668 0.8 696 0.6 724 4.3 752 5 807 6.6 238 Time F_ Time F Time F Time F_ Time F_ Time F_ 807 6.8 835 4 863 6.5 890 4.8 917 5.4 945 4.2 808 6.9 835 3.5 863 6.7 890 4.8 918 5.4 945 4.1 808 7.1 836 3.1 864 6.9 891 4.9 918 5.3 946 4.1 809 7.2 836 3.1 864 7.1 891 5 919 5.3 946 4.1 809 7.3 837 3 865 7.3 892 4.9 919 5.3 947 4.1 810 7.4 837 2.9 865 7.5 892 4.9 920 5.3 947 4.1 810 7.5 838 2.8 866 7.7 893 4.6 920 5.3 948 4.1 811 7.5 838 2.7 866 7.8 893 -0.6 921 5.3 948 4.2 811 7.6 839 2.6 867 8 894 0 921 5.3 949 4.2 812 7.7 839 2.6 867 8.2 894 1 922 5.3 949 4.2 812 7.8 840 2.6 868 8.4 895 1.7 922 5.3 950 4.1 813 8 840 2.5 895 2.3 923 5.3 950 4.1 813 8.1 841 2.5 868 8.6 896 2.7 924 5.3 951 4.2 814 8.3 841 2.5 869 8.8 896 3 924 5.3 951 4.3 814 8.4 842 2.5 869 8.9 897 3.2 925 5.4 952 4.2 815 8.6 842 2.4 870 9.1 897 3.4 925 5.4 952 4.1 815 8.7 843 2.4 870 9.2 898 3.6 926 5.5 953 4 816 8.8 843 2.3 871 9.3 898 3.8 926 5.5 816 8.9 844 2.3 871 9.4 899 3.9 927 5.6 953 4 817 9.1 844 2.2 872 9.6 899 4.1 927 5.6 954 4 817 9.2 845 2.1 872 9.7 900 4.3 928 5.7 954 3.9 818 9.4 845 1 873 9.8 900 4.5 928 5.7 955 3.9 818 9.5 873 7.1 901 4.7 929 5.8 955 3.8 819 9.7 846 1.3 874 3 901 4.8 929 5.8 956 3.8 819 9.8 846 1.6 874 3.2 902 5 930 5.8 956 3.8 820 9.8 847 1.8 875 3.5 902 5.1 930 5.8 957 3.8 820 9.9 847 2 875 3.7 903 5.3 931 5.7 957 3.7 821 10 848 2.3 876 3.9 903 5.4 931 5.6 958 3.7 821 9.8 848 2.4 876 4.1 904 5.6 932 5.5 958 3.7 822 9.5 849 2.6 877 4.3 904 5.7 932 5.6 959 3.6 822 9.3 849 2.8 877 4.5 905 5.8 933 5.6 959 3.6 823 9 850 3 878 4.7 905 5.9 933 5.6 960 3.6 823 8.8 850 3.1 878 4.8 906 6 934 5.5 960 3.5 851 3.3 879 5 906 6.1 961 3.5 824 8.5 851 3.5 879 5.2 907 6.2 934 5.6 961 3.5 824 8.3 852 3.6 880 5.4 907 6.3 935 5.8 962 3.5 825 8 852 3.8 880 5.6 908 6.3 935 5.9 962 3.4 825 7.7 853 4 881 5.7 908 6.4 936 6 826 7.3 853 4.1 881 5.9 909 6.4 936 6.1 963 3.4 826 7 854 4.3 882 6 909 6.5 937 6.2 963 3.4 827 6.6 854 4.4 882 6.2 910 6.5 937 6.2 964 3.4 827 6.3 855 4.6 883 6.4 910 6.6 938 6.2 964 3.3 828 6.2 855 4.7 883 6.5 911 6.6 938 6.2 965 3.2 828 6.2 856 4.9 884 6.6 911 6.6 939 6.2 965 3.2 829 6.1 856 5.1 884 6.7 939 6.2 966 3.2 829 6 857 5.2 885 6.8 912 6.6 940 6.2 966 3.2 830 6 857 5.4 885 6.9 912 6.4 940 6.2 967 3.3 830 6 858 5.6 886 6.5 913 6.2 941 6.1 967 3.3 831 6 858 5.7 886 4 913 6.1 941 6 968 3.2 831 5.7 859 5.8 887 4.2 914 5.9 942 5.1 968 3.1 832 5.2 859 6 887 4.4 914 5.8 942 3.6 969 3.1 832 4.8 860 6.2 888 4.5 915 5.8 943 3.7 969 3.1 833 4.5 860 6.3 888 4.7 915 5.7 943 3.9 970 3.2 833 4.3 861 6.5 889 4.8 916 5.5 970 3.2 834 4.3 862 6.7 889 4.8 916 5.5 944 4 971 3.1 834 4.2 862 6.6 917 5.4 944 4.1 971 3 239 Time F_ Time F_ Time F_ Time F_ Time F_ Time F_ 972 3 975 2.8 978 2.6 985 3.7 989 4.2 975 2.7 979 2.6 982 3.2 986 3.8 989 4.2 972 3 976 2.5 979 2.7 982 3.3 986 4 990 4.3 973 3.1 976 2.4 980 2.8 983 3.4 987 4.1 990 4.1 973 3 977 2.5 980 2.8 983 3.5 987 4.1 991 1.9 974 2.9 977 2.5 981 3 984 3.5 988 4.1 991 1.9 974 2.9 978 2.5 981 3.1 984 3.6 988 4.1 240 t^t^cxiodododcocoodoNaNONaNcxJcoodceooooodododod mooc<-ioocnoomoomoomoocnoomoocnoO'5tO\"*0\'^-o\TtONT)-o\ ON Tf ON Tf ON Tf ON •<* ON o©-H^ o r~ r- r^ r~t~~t~~t-r~t-0O0O0O0O0O0O0O0O0O0O0O0O0O0O0O0O0O0O000OONONO\O\ONONONONONONONON S3 1) o W^ooc^qHNNqnNnHf^N(^|^^e^ooflJqrtH(>^m^ln\q^o^OlO'o^^ m co •* © a, © © d -^ c o p>op oo(i;HM^^hO\qH(fi^\qi-. qNfiin«ooq'Hci((jin\qt -o\qfj(nifiri 00 ON ON © © —I -H CN CN CO CO •* Tt>nmNO\ot— r~-ooooONONOO-H^Ho)cNcocoTj-'^-invovor--r- g CO CO CO *—» s- o 00 W oo (N ^ in N ONOorfcovoi^vo fclOOOOONONONO^^CNCO^ln^C^OOONp-^C^C^C^C^C^CNCOCOTf dddddHHHHH'HHHH'HHNNNNNNNNNNNNNNNNNNririMd 242 Time F Time F Time F Time F Time F Time F 248.5 6.1 270.7 6.3 292.9 5.7 315.0 3.6 337.2 -0.5 359.4 7.4 249.0 6.1 271.2 6.4 293.4 5.6 315.5 3.7 337.7 -0.3 359.9 7.5 249.5 6.2 271.7 6.5 293.9 5.5 316.1 3.9 338.2 -0.1 360.4 7.7 250.0 6.2 272.2 6.5 294.4 5.4 316.6 4.0 338.7 0.0 360.9 7.9 250.5 6.3 272.7 6.5 294.9 5.2 317.1 4.1 339.2 0.2 361.4 8.0 251.0 6.5 273.2 6.6 295.4 5.0 317.6 4.2 339.7 0.4 361.9 8.2 251.5 6.6 273.7 6.7 295.9 4.9 318.1 4.3 340.2 0.6 362.4 8.3 252.0 6.7 274.2 6.6 296.4 4.9 318.6 4.4 340.8 0.8 362.9 8.4 252.5 6.7 274.7 6.5 296.9 4.9 319.1 4.5 341.3 1.0 363.4 8.5 253.0 6.5 275.2 6.3 297.4 4.9 319.6 4.6 341.8 1.2 363.9 8.7 253.5 6.4 275.7 6.4 297.9 4.9 320.1 4.7 342.3 1.4 364.4 8.8 254.1 6.4 276.2 6.6 298.4 4.9 320.6 4.8 342.8 1.6 364.9 8.8 254.6 6.4 276.7 6.7 298.9 5.0 321.1 4.9 343.3 1.8 365.5 8.9 255.1 6.3 277.2 6.8 299.4 5.1 321.6 5.0 343.8 2.0 366.0 9.0 255.6 6.2 277.7 6.9 299.9 5.1 322.1 5.0 344.3 2.1 366.5 9.0 256.1 6.1 278.2 6.8 300.4 5.1 322.6 5.2 344.8 2.3 367.0 8.9 256.6 6.1 278.8 6.4 300.9 5.1 323.1 5.2 345.3 2.5 367.5 8.7 257.1 6.0 279.3 6.3 301.4 5.0 323.6 5.3 345.8 2.7 368.0 8.7 257.6 6.1 279.8 6.4 301.9 5.0 324.1 5.4 346.3 2.9 368.5 8.7 258.1 6.1 280.3 6.4 302.4 4.9 324.6 5.6 346.8 3.1 369.0 8.8 258.6 6.1 280.8 6.5 302.9 4.9 325.1 5.7 347.3 3.3 369.5 8.8 259.1 6.1 281.3 6.6 303.5 4.9 325.6 5.8 347.8 3.5 370.0 8.7 259.6 6.0 281.8 6.7 304.0 4.7 326.1 5.9 348.3 3.7 370.5 8.3 260.1 6.1 282.3 6.7 304.5 4.0 326.6 6.1 348.8 3.9 371.0 7.9 260.6 6.3 282.8 6.7 305.0 4.1 327.1 6.1 349.3 4.0 371.5 7.4 261.1 6.4 283.3 6.6 305.5 4.0 327.6 6.2 349.8 4.2 372.0 7.4 261.6 6.5 283.8 6.5 306.0 4.0 328.2 6.3 350.3 4.4 372.5 7.4 262.1 6.6 284.3 6.5 306.5 4.1 328.7 6.4 350.8 4.6 373.0 7.4 262.6 6.6 284.8 6.4 307.0 4.1 329.2 6.4 351.3 4.7 373.5 7.5 263.1 6.6 285.3 6.3 307.5 4.2 329.7 6.3 351.8 4.9 374.0 7.5 263.6 6.8 285.8 6.2 308.0 4.2 330.2 6.1 352.3 5.1 374.5 7.6 264.1 6.9 286.3 6.1 308.5 4.2 330.7 6.1 352.8 5.3 375.0 7.6 264.6 7.0 286.8 6.0 309.0 3.2 331.2 6.2 353.4 5.4 375.5 7.6 265.1 6.9 287.3 6.0 309.5 3.4 331.7 6.1 353.9 5.6 376.0 7.6 265.6 6.3 287.8 6.0 310.0 3.6 332.2 6.2 354.4 5.8 376.5 7.5 266.1 6.0 288.3 6.0 310.5 3.6 332.7 6.1 354.9 5.9 377.0 7.3 266.7 6.0 288.8 6.0 311.0 3.7 333.2 5.2 355.4 6.1 377.5 7.3 267.2 6.1 289.3 6.0 311.5 3.7 333.7 4.5 355.9 6.3 378.1 7.3 267.7 6.1 289.8 5.9 312.0 3.2 334.2 4.7 356.4 6.4 378.6 7.2 268.2 6.0 290.3 5.9 312.5 2.8 334.7 2.5 356.9 6.6 379.1 7.0 268.7 6.0 290.8 5.9 313.0 3.0 335.2 0.1 357.4 6.8 379.6 7.0 269.2 6.1 291.4 5.9 313.5 3.1 335.7 -0.1 357.9 6.9 380.1 6.9 269.7 6.2 291.9 5.9 314.0 3.3 336.2 -0.2 358.4 7.1 380.6 7.0 270.2 6.2 292.4 5.8 314.5 3.4 336.7 -0.5 358.9 7.2 381.1 7.1 243 Time F Time F Time F Time F Time F Time F 381.6 7.1 403.8 3.3 425.9 5.1 448.1 4.6 470.3 4.2 492.5 2.7 382.1 7.2 404.3 3.4 426.4 5.1 448.6 4.7 470.8 4.2 493.0 2.9 382.6 7.1 404.8 3.5 426.9 5.1 449.1 4.7 471.3 4.2 493.5 3.0 383.1 7.2 405.3 3.6 427.5 5.1 449.6 4.7 471.8 4.1 494.0 3.1 383.6 7.2 405.8 3.6 428.0 5.1 450.1 4.7 472.3 4.1 494.5 2.6 384.1 7.2 406.3 3.6 428.5 5.1 450.6 4.6 472.8 4.2 495.0 2.5 384.6 7.2 406.8 3.6 429.0 5.2 451.1 4.5 473.3 4.3 495.5 2.6 385.1 7.1 407.3 3.6 429.5 5.2 451.6 4.4 473.8 4.3 496.0 2.4 385.6 7.0 407.8 3.6 430.0 5.2 452.2 4.4 474.3 4.3 496.5 2.4 386.1 7.0 408.3 3.7 430.5 5.1 452.7 4.4 474.8 4.2 497.0 1.3 386.6 7.1 408.8 3.7 431.0 5.1 453.2 4.4 475.3 4.2 497.5 1.5 387.1 7.2 409.3 3.8 431.5 5.1 453.7 4.4 475.8 4.1 498.0 1.7 387.6 7.2 409.8 3.8 432.0 5.1 454.2 4.4 476.3 4.0 498.5 1.8 388.1 7.2 410.3 3.9 432.5 5.1 454.7 4.4 476.9 3.9 499.0 1.9 388.6 7.3 410.8 3.9 433.0 5.1 455.2 4.4 477.4 3.9 499.5 2.1 389.1 7.3 411.3 4.0 433.5 5.1 455.7 4.4 477.9 4.0 500.0 2.3 389.6 7.2 411.8 4.1 434.0 5.0 456.2 4.4 478.4 4.0 500.5 2.4 390.2 7.1 412.3 4.2 434.5 5.0 456.7 4.5 478.9 3.9 501.0 2.6 390.7 7.1 412.8 4.2 435.0 5.0 457.2 4.5 479.4 3.4 501.5 2.7 391.2 7.0 413.3 4.2 435.5 5.0 457.7 4.5 479.9 3.5 502.1 2.9 391.7 7.0 413.8 4.3 436.0 5.0 458.2 4.6 480.4 3.6 502.6 3.1 392.2 6.9 414.3 4.3 436.5 5.0 458.7 4.6 480.9 3.6 503.1 3.2 392.7 6.7 414.9 4.4 437.0 4.9 459.2 4.6 481.4 3.6 503.6 3.4 393.2 6.4 415.4 4.5 437.5 4.9 459.7 4.6 481.9 3.6 504.1 3.5 393.7 5.9 415.9 4.7 438.0 5.0 460.2 4.5 482.4 3.5 504.6 3.7 394.2 4.8 416.4 4.6 438.5 5.1 460.7 4.5 482.9 3.4 505.1 3.8 394.7 4.7 416.9 4.6 439.0 5.2 461.2 4.5 483.4 3.4 505.6 4.0 395.2 4.7 417.4 4.7 439.5 5.2 461.7 4.5 483.9 3.4 506.1 4.1 395.7 4.8 417.9 4.8 440.1 5.2 462.2 4.2 484.4 3.5 506.6 4.3 396.2 4.7 418.4 4.8 440.6 5.1 462.7 4.1 484.9 3.5 507.1 4.4 396.7 4.3 418.9 4.9 441.1 5.1 463.2 4.1 485.4 3.5 507.6 4.6 397.2 3.9 419.4 5.0 441.6 5.0 463.7 4.0 485.9 3.5 508.1 4.7 397.7 3.9 419.9 5.1 442.1 4.9 464.2 4.1 486.4 3.5 508.6 4.8 398.2 4.0 420.4 5.1 442.6 4.9 464.8 4.2 486.9 3.5 509.1 4.9 398.7 4.1 420.9 5.1 443.1 4.9 465.3 4.3 487.4 3.6 509.6 5.1 399.2 4.2 421.4 5.2 443.6 4.8 465.8 4.4 487.9 3.6 510.1 5.2 399.7 4.2 421.9 5.2 444.1 4.9 466.3 4.4 488.4 3.7 510.6 5.4 400.2 4.3 422.4 5.2 444.6 4.9 466.8 4.5 488.9 3.8 511.1 5.5 400.7 4.3 422.9 5.2 445.1 4.8 467.3 4.5 489.5 3.8 511.6 5.6 401.2 3.3 423.4 5.2 445.6 4.8 467.8 3.9 490.0 3.8 512.1 5.7 401.7 2.6 423.9 5.3 446.1 4.7 468.3 3.8 490.5 3.8 512.6 5.8 402.2 2.3 424.4 5.2 446.6 4.7 468.8 3.9 491.0 3.8 513.1 5.9 402.8 2.7 424.9 5.3 447.1 4.6 469.3 4.0 491.5 3.8 513.6 6.0 403.3 3.1 425.4 5.2 447.6 4.6 469.8 4.1 492.0 3.4 514.2 6.2 244 Time F Time F Time F Time F Time F Time F 514.7 6.3 536.8 7.9 559.0 10.5 581.2 5.9 603.4 4.0 625.6 4.8 515.2 6.3 537.3 8.0 559.5 10.5 581.7 6.0 603.9 4.1 626.1 4.9 515.7 2.8 537.8 8.2 560.0 10.5 582.2 6.0 604.4 4.2 626.6 4.9 516.2 1.2 538.3 8.3 560.5 10.5 582.7 6.0 604.9 4.4 627.1 4.6 516.7 1.8 538.9 8.5 561.0 10.5 583.2 6.1 605.4 4.5 627.6 4.4 517.2 1.8 539.4 8.6 561.5 10.6 583.7 6.1 605.9 4.6 628.1 4.4 517.7 1.7 539.9 8.8 562.0 10.6 584.2 6.2 606.4 4.8 628.6 4.5 518.2 2.1 540.4 8.9 562.5 10.7 584.7 6.3 606.9 4.9 629.1 4.7 518.7 2.6 540.9 9.1 563.0 10.7 585.2 6.4 607.4 4.9 629.6 4.7 519.2 2.9 541.4 9.2 563.5 10.8 585.7 6.5 607.9 4.9 630.1 4.6 519.7 3.2 541.9 9.3 564.1 10.8 586.2 6.5 608.4 4.9 630.6 4.5 520.2 3.5 542.4 9.3 564.6 10.8 586.7 6.5 608.9 5.0 631.1 4.5 520.7 3.7 542.9 9.2 565.1 10.8 587.2 6.6 609.4 5.0 631.6 4.3 521.2 3.8 543.4 9.3 565.6 10.8 587.7 6.6 609.9 5.1 632.1 3.9 521.7 4.0 543.9 9.3 566.1 10.9 588.2 6.6 610.4 5.2 632.6 3.9 522.2 4.2 544.4 9.4 566.6 10.7 588.8 6.6 610.9 5.3 633.1 3.9 522.7 4.3 544.9 9.5 567.1 9.7 589.3 6.6 611.4 5.4 633.6 4.0 523.2 4.5 545.4 9.5 567.6 6.8 589.8 6.6 611.9 5.4 634.1 3.9 523.7 4.6 545.9 9.5 568.1 5.6 590.3 6.6 612.4 5.5 634.6 3.6 524.2 4.8 546.4 9.6 568.6 5.0 590.8 6.6 612.9 5.5 635.1 1.1 524.7 4.9 546.9 9.6 569.1 4.8 591.3 6.6 613.5 5.6 635.6 0.9 525.2 5.1 547.4 9.6 569.6 4.8 591.8 6.5 614.0 5.8 636.1 1.0 525.7 5.3 547.9 9.6 570.1 4.8 592.3 5.8 614.5 5.9 636.6 1.1 526.2 5.4 548.4 9.6 570.6 4.8 592.8 4.5 615.0 6.1 637.1 1.1 526.8 5.5 548.9 9.7 571.1 4.8 593.3 4.0 615.5 6.1 637.6 1.1 527.3 5.7 549.4 9.8 571.6 4.9 593.8 4.0 616.0 5.6 638.2 1.0 527.8 5.8 549.9 9.8 572.1 4.9 594.3 4.0 616.5 5.4 638.7 1.1 528.3 6.0 550.4 9.8 572.6 4.9 594.8 4.0 617.0 5.4 639.2 1.1 528.8 6.1 550.9 9.9 573.1 4.9 595.3 4.1 617.5 5.6 639.7 0.7 529.3 6.3 551.5 9.9 573.6 4.9 595.8 3.8 618.0 5.7 640.2 0.2 529.8 6.4 552.0 10.0 574.1 5.0 596.3 3.7 618.5 5.7 640.7 0.1 530.3 6.5 552.5 10.0 574.6 5.0 596.8 3.7 619.0 5.8 641.2 0.2 530.8 6.6 553.0 10.1 575.1 5.1 597.3 2.7 619.5 4.2 641.7 0.3 531.3 6.6 553.5 10.2 575.6 5.3 597.8 2.7 620.0 3.8 642.2 0.4 531.8 6.7 554.0 10.3 576.2 5.4 598.3 2.9 620.5 4.0 642.7 0.5 532.3 6.8 554.5 10.3 576.7 5.4 598.8 3.1 621.0 4.1 643.2 0.6 532.8 6.9 555.0 10.3 577.2 5.4 599.3 3.2 621.5 4.2 643.7 0.8 533.3 7.0 555.5 10.3 577.7 5.5 599.8 3.3 622.0 4.3 644.2 0.9 533.8 7.1 556.0 10.3 578.2 5.5 600.3 3.4 622.5 4.4 644.7 1.0 534.3 7.2 556.5 10.3 578.7 5.5 600.9 3.4 623.0 4.4 645.2 1.1 534.8 7.4 557.0 10.4 579.2 5.6 601.4 3.5 623.5 4.4 645.7 1.2 535.3 7.5 557.5 10.4 579.7 5.6 601.9 3.6 624.0 4.5 646.2 1.2 535.8 7.6 558.0 10.4 580.2 5.7 602.4 3.7 624.5 4.6 646.7 1.2 536.3 7.7 558.5 10.5 580.7 5.9 602.9 3.8 625.0 4.7 647.2 1.4 245 Time F Time F Time F Time F Time F Time F 647.7 1.5 669.9 3.0 692.1 7.5 714.3 8.1 736.4 3.5 758.6 3.2 648.2 1.6 670.4 3.1 692.6 7.7 714.8 7.7 737.0 3.7 759.1 3.2 648.7 1.6 670.9 2.3 693.1 7.8 715.3 7.5 737.5 3.8 759.6 3.2 649.2 1.5 671.4 2.1 693.6 8.0 715.8 7.4 738.0 3.9 760.1 3.0 649.7 1.4 671.9 2.2 694.1 8.2 716.3 7.3 738.5 4.0 760.6 2.9 650.3 1.4 672.4 2.3 694.6 8.4 716.8 7.3 739.0 4.0 761.1 2.5 650.8 1.4 672.9 2.4 695.1 8.5 717.3 7.2 739.5 4.0 761.7 2.6 651.3 1.6 673.4 2.5 695.6 8.7 717.8 6.2 740.0 4.0 762.2 2.4 651.8 1.6 673.9 2.7 696.1 8.8 718.3 5.8 740.5 4.0 762.7 2.6 652.3 1.6 674.4 2.8 696.6 9.0 718.8 5.9 741.0 4.0 763.2 2.3 652.8 1.7 675.0 3.0 697.1 9.1 719.3 6.0 741.5 4.0 763.7 0.0 653.3 1.8 675.5 3.2 697.6 9.3 719.8 6.0 742.0 3.9 764.2 0.4 653.8 1.9 676.0 3.4 698.1 9.5 720.3 6.1 742.5 3.8 764.7 1.2 654.3 2.0 676.5 3.5 698.6 9.6 720.8 6.2 743.0 3.6 765.2 2.0 654.8 2.0 677.0 3.7 699.1 9.8 721.3 6.2 743.5 3.5 765.7 2.4 655.3 1.9 677.5 3.9 699.7 9.9 721.8 6.2 744.0 3.5 766.2 2.6 655.8 2.0 678.0 4.1 700.2 10.1 722.3 6.1 744.5 3.6 766.7 2.7 656.3 1.7 678.5 4.2 700.7 10.2 722.8 6.1 745.0 3.6 767.2 2.9 656.8 1.2 679.0 4.4 701.2 10.4 723.3 6.0 745.5 3.6 767.7 3.0 657.3 0.9 679.5 4.6 701.7 10.6 723.8 5.9 746.0 3.6 768.2 3.2 657.8 0.9 680.0 4.7 702.2 10.7 724.3 5.8 746.5 3.3 768.7 3.3 658.3 1.1 680.5 4.9 702.7 10.9 724.9 5.8 747.0 3.2 769.2 3.4 658.8 1.2 681.0 5.0 703.2 11.0 725.4 5.7 747.5 3.3 769.7 3.4 659.3 1.3 681.5 5.2 703.7 11.1 725.9 5.6 748.0 3.4 770.2 3.5 659.8 1.5 682.0 5.3 704.2 11.2 726.4 5.6 748.5 3.5 770.7 3.6 660.3 1.6 682.5 5.5 704.7 11.3 726.9 5.5 749.0 3.6 771.2 3.7 660.8 1.7 683.0 5.6 705.2 11.3 727.4 5.5 749.6 3.6 771.7 3.8 661.3 1.7 683.5 5.7 705.7 11.1 727.9 5.4 750.1 3.7 772.2 3.9 661.8 1.7 684.0 5.8 706.2 10.4 728.4 5.2 750.6 3.7 772.7 3.9 662.3 1.8 684.5 5.9 706.7 9.6 728.9 5.2 751.1 3.8 773.2 4.0 662.9 2.0 685.0 6.0 707.2 9.0 729.4 5.1 751.6 3.8 773.7 4.1 663.4 2.1 685.5 6.1 707.7 8.9 729.9 5.1 752.1 3.9 774.3 4.2 663.9 2.2 686.0 6.3 708.2 9.0 730.4 5.1 752.6 3.9 774.8 4.2 664.4 2.2 686.5 6.4 708.7 9.0 730.9 5.2 753.1 3.8 775.3 4.1 664.9 2.4 687.0 6.5 709.2 9.0 731.4 5.2 753.6 3.5 775.8 4.1 665.4 2.5 687.6 6.6 709.7 9.1 731.9 5.2 754.1 3.4 776.3 4.1 665.9 2.6 688.1 6.7 710.2 9.0 732.4 5.1 754.6 3.3 776.8 4.1 666.4 2.7 688.6 6.9 710.7 9.0 732.9 5.1 755.1 3.4 777.3 4.2 666.9 2.8 689.1 7.0 711.2 8.9 733.4 5.1 755.6 3.4 777.8 4.2 667.4 2.9 689.6 7.2 711.7 8.8 733.9 5.0 756.1 3.2 778.3 4.2 667.9 3.0 690.1 7.3 712.3 8.7 734.4 4.9 756.6 3.0 778.8 4.3 668.4 3.0 690.6 7.4 712.8 8.4 734.9 4.8 757.1 3.1 779.3 4.3 668.9 3.0 691.1 7.3 713.3 8.3 735.4 4.4 757.6 3.1 779.8 4.0 669.4 3.0 691.6 7.4 713.8 8.2 735.9 3.3 758.1 3.1 780.3 4.1 246 Time F Time F Time F Time F Time F Time F 780.8 4.2 803.0 3.1 825.2 6.1 847.3 3.9 869.5 5.0 891.7 4.7 781.3 4.3 803.5 3.1 825.7 6.1 847.8 3.9 870.0 4.9 892.2 4.8 781.8 4.3 804.0 3.2 826.2 6.1 848.4 3.9 870.5 4.9 892.7 4.9 782.3 3.6 804.5 3.3 826.7 6.1 848.9 4.0 871.0 4.7 893.2 4.9 782.8 2.8 805.0 3.4 827.2 6.1 849.4 4.0 871.5 4.6 893.7 4.9 783.3 2.5 805.5 3.5 827.7 6.0 849.9 4.0 872.0 4.5 894.2 5.0 783.8 2.6 806.0 3.6 828.2 6.0 850.4 4.1 872.5 4.4 894.7 5.1 784.3 2.8 806.5 3.6 828.7 5.9 850.9 4.2 873.1 4.4 895.2 5.2 784.8 2.9 807.0 3.7 829.2 5.8 851.4 4.3 873.6 4.3 895.7 5.3 785.3 3.1 807.5 3.8 829.7 5.8 851.9 4.3 874.1 4.4 896.2 5.4 785.8 3.1 808.0 3.9 830.2 5.7 852.4 4.3 874.6 4.4 896.7 5.6 786.4 3.2 808.5 4.0 830.7 5.5 852.9 4.4 875.1 4.4 897.2 5.7 786.9 3.3 809.0 4.1 831.2 5.4 853.4 4.5 875.6 4.4 897.8 5.7 787.4 3.3 809.5 4.2 831.7 5.3 853.9 4.5 876.1 4.4 898.3 5.8 787.9 3.4 810.0 4.2 832.2 5.3 854.4 4.5 876.6 4.3 898.8 5.9 788.4 3.5 810.5 4.3 832.7 5.2 854.9 4.5 877.1 4.2 899.3 6.0 788.9 3.5 811.1 4.3 833.2 5.2 855.4 4.6 877.6 4.1 899.8 6.1 789.4 3.5 811.6 4.5 833.7 5.1 855.9 4.7 878.1 4.0 900.3 6.3 789.9 3.5 812.1 4.6 834.2 5.1 856.4 4.8 878.6 4.0 900.8 6.4 790.4 3.5 812.6 4.2 834.7 3.9 856.9 4.9 879.1 4.0 901.3 6.5 790.9 3.6 813.1 4.2 835.2 1.4 857.4 4.9 879.6 4.0 901.8 6.6 791.4 3.5 813.6 4.3 835.7 2.0 857.9 4.9 880.1 4.0 902.3 6.7 791.9 3.4 814.1 4.3 836.3 2.3 858.4 4.9 880.6 4.0 902.8 6.8 792.4 3.4 814.6 4.5 836.8 2.5 858.9 4.9 881.1 3.9 903.3 6.9 792.9 3.4 815.1 4.6 837.3 2.7 859.4 5.0 881.6 3.9 903.8 7.1 793.4 2.7 815.6 4.7 837.8 2.9 859.9 5.0 882.1 4.0 904.3 7.2 793.9 2.2 816.1 4.8 838.3 3.1 860.4 5.0 882.6 4.1 904.8 7.3 794.4 2.4 816.6 4.9 838.8 3.2 861.0 5.0 883.1 4.2 905.3 7.4 794.9 2.5 817.1 5.0 839.3 3.4 861.5 5.0 883.6 4.2 905.8 7.5 795.4 2.6 817.6 5.0 839.8 3.5 862.0 5.0 884.1 4.1 906.3 7.6 795.9 2.8 818.1 5.2 840.3 3.6 862.5 5.0 884.6 4.2 906.8 7.7 796.4 2.9 818.6 5.3 840.8 3.7 863.0 5.0 885.1 4.2 907.3 7.8 796.9 3.0 819.1 5.4 841.3 3.8 863.5 5.0 885.7 4.2 907.8 7.8 797.4 2.3 819.6 5.5 841.8 3.9 864.0 5.0 886.2 4.2 908.3 7.6 797.9 2.4 820.1 5.5 842.3 4.0 864.5 5.0 886.7 4.2 908.8 7.6 798.4 2.5 820.6 5.6 842.8 4.1 865.0 4.9 887.2 4.2 909.3 7.7 799.0 2.7 821.1 5.6 843.3 4.2 865.5 4.9 887.7 4.2 909.8 7.9 799.5 2.7 821.6 5.7 843.8 4.3 866.0 4.9 888.2 4.3 910.4 8.0 800.0 2.8 822.1 5.8 844.3 3.9 866.5 4.9 888.7 4.3 910.9 8.1 800.5 2.9 822.6 5.9 844.8 3.8 867.0 5.0 889.2 4.4 911.4 8.2 801.0 2.9 823.1 6.0 845.3 3.8 867.5 4.9 889.7 4.4 911.9 8.2 801.5 2.9 823.7 6.0 845.8 3.9 868.0 4.9 890.2 4.6 912.4 8.3 802.0 3.0 824.2 6.0 846.3 4.0 868.5 5.0 890.7 4.7 912.9 8.3 802.5 3.0 824.7 6.1 846.8 4.0 869.0 5.0 891.2 4.7 913.4 8.4 247 O—itSTj-mvor-ooo nHNpiNNNcicicicinci '*a\'«a;o\'S;o\^;ON>r)0>op c^t^c^oocnoq<^oqc<^oqcooqc^oorooocooocnoqcnoqcnoqcnoqc^ odooONONOd — — c^rJcocOTtTtininNdNdr^r^ododoNaNddrtrtc^c^c^ >t /1 « h » 00 — M n in iq i-; 000000000000000000000000000 — ^-^^ —;*£>-^\O-H NO -* vo — ^ ^ ^ "-! ^ "i ^ Tl^'l ^^ ^ -l ^t^t~:cs!r~:rit~:rir~:ts!r~:cir~:cir~:cir~:cir~: ON rt ON rf ON Tt ON ^ ON ^ OS ^t ON ON "* o\ •* o >n o m o >n o u~t >r> p >o p 10 p>op>np>op>o O m -H VO CI Normality Test of UTM Data Normality Test for Cutting Force Data Sample with out aeration 99.99- i i 1 i i • i Mean 4.317 ! 1 ! IT ! 1 1 i StDev 2.404 I i ! N 1967 i t 1 i — _i 99- € 1 KS 0.082 i 1 | > i 1 i 1 P-Value <0.010 95- "T" _, ; T 1 I 1 t ! ! >. — 1. 80- i | 1 — 1 V i ~l L 4 . 1 *£. 1 L ^ 1 I 1 1 50- -I 1 s 1 ! i i 1 £ 20- T -4--- -— 1 1 i ! i i ^ f 5- ! 1 1 1 1 i ! T _ j— -— _1 1- 1- | ! 1 1 1 i I 1 ! 1 1 1 if j 1 1 j 1 t i ! i 0.01- i —i— r- 5 10 15 FX Normality test for Cutting force data Sample after Aeration 99.99 Mean 5.016 StDev 2.502 N 1967 99 KS 0.049 P-Value <0.010 95 80 50 - I 20 5 fi=^l 1 0.01 1 i 1 1 1 0 5 10 15 FX With aeration 249 APPENDIX K SEM and UTM Data Electron Beam Energy = 0.2 to 40 KeV Resolution 4 nm Accelerating voltage = 300 V - 30KV Magnification range = 15x - 300,000 X Probe current = lpA- 500 nA 0.4nm-30KeV 1.6nm-lKeV Sputter coating thickness = 1-5 nm 250 APPENDIX L X-ray Diffraction Data Gravity Gravity Blow Blow Blow Blow Aeration Aeration Aeration 29 1 2 1 2 3 4 1 2 3 20.00 2 858 878 878 878 1087 751 709 813 20.02 1 810 845 845 845 1146 709 764 814 20.04 2 884 859 859 859 1051 731 709 807 20.06 3 816 835 835 835 1111 715 735 806 20.08 3 789 825 825 825 1147 735 759 807 20.10 2 876 829 829 829 1121 714 779 832 20.12 1 873 850 850 850 1085 704 725 805 20.14 2 845 853 853 853 1124 739 723 801 20.16 3 803 843 843 843 1131 783 739 800 20.18 3 861 854 854 854 1113 736 750 789 20.20 1 815 786 786 786 1138 709 720 832 20.22 1 860 833 833 833 1076 758 717 795 20.24 1 847 871 871 871 1069 725 747 789 20.26 3 847 904 904 904 1078 751 732 827 20.28 3 863 857 857 857 1061 717 702 860 20.30 2 873 877 877 877 1120 723 700 833 20.32 3 855 823 823 823 1089 729 709 847 20.34 3 873 853 853 853 1131 763 742 843 20.36 3 878 857 857 857 1090 674 736 814 20.38 1 895 880 880 880 1061 749 707 856 20.40 1 873 915 915 915 1105 729 735 844 20.42 585 882 876 876 876 1077 718 697 844 20.44 922 873 869 869 869 1105 723 706 829 20.46 963 844 904 904 904 1090 761 729 843 20.48 951 846 874 874 874 1094 700 715 807 20.50 933 876 901 901 901 1191 707 750 807 20.52 968 894 927 927 927 1191 710 696 814 20.54 987 869 892 892 892 1217 742 708 899 20.56 907 894 893 893 893 1313 725 656 799 20.58 1005 885 893 893 893 1379 757 728 853 20.60 959 890 900 900 900 1492 722 731 827 20.62 921 879 935 935 935 1515 765 710 862 20.64 936 870 933 933 933 1602 693 731 870 20.66 929 941 911 911 911 1778 771 725 849 20.68 911 917 909 909 909 1887 751 746 853 20.70 913 880 921 921 921 2132 705 717 838 20.72 943 805 883 883 883 2292 717 719 864 20.74 959 903 897 897 897 2366 737 692 865 20.76 927 854 919 919 919 2427 731 719 879 20.78 920 901 957 957 957 2319 702 703 821 251 Gravity Gravity Blow Blow Blow Blow Aeration Aeration Aeration 29 1 2 12 3 4 12 3 20.80 914 867 899 899 899 2136 768 715 834 20.82 892 849 909 909 909 2029 783 733 819 20.84 959 857 913 913 913 2073 803 733 777 20.86 925 894 907 907 907 2005 786 717 857 20.88 931 832 847 847 847 2001 789 707 867 20.90 943 903 897 897 897 1982 782 737 833 20.92 980 873 946 946 946 2065 763 753 828 20.94 939 879 890 890 890 2027 810 747 809 20.96 989 901 899 899 899 2044 749 737 820 20.98 951 920 951 951 951 2140 781 748 812 21.00 957 887 905 905 905 2106 799 715 834 21.02 959 899 885 885 885 2232 790 751 841 21.04 1065 919 888 888 888 2091 741 753 840 21.06 1121 951 914 914 914 2167 752 758 812 21.08 1102 903 944 944 944 2080 763 781 852 21.10 1134 915 937 937 937 2107 751 763 848 21.12 1185 963 943 943 943 1989 768 751 841 21.14 1139 961 913 913 913 1954 740 749 845 21.16 1151 1057 924 924 924 1770 765 763 845 21.18 1175 1037 903 903 903 1612 812 762 818 21.20 1203 1067 880 880 880 1564 738 776 817 21.22 1181 1133 958 958 958 1485 749 757 815 21.24 1251 1158 961 961 961 1374 768 798 853 21.26 1198 1247 959 959 959 1227 742 741 821 21.28 1286 1316 943 943 943 1215 767 767 818 21.30 1329 1350 1004 1004 1004 1185 791 737 839 21.32 1394 1431 1067 1067 1067 1136 759 738 875 21.34 1481 1455 1038 1038 1038 1181 757 736 865 21.36 1481 1509 1048 1048 1048 1103 741 747 862 21.38 1707 1473 1247 1247 1247 1043 721 724 843 21.40 1921 1522 1275 1275 1275 1045 765 759 813 21.42 2107 1483 1309 1309 1309 1062 770 747 867 21.44 2281 1585 1345 1345 1345 1056 778 731 867 21.46 2381 1506 1401 1401 1401 1096 720 765 908 21.48 2571 1477 1353 1353 1353 1053 814 735 881 21.50 2612 1535 1391 1391 1391 1057 792 773 924 21.52 2763 1657 1510 1510 1510 1075 800 745 915 21.54 2869 1768 1537 1537 1537 1013 749 731 998 21.56 2909 1929 1536 1536 1536 1037 797 722 1141 21.58 2699 2239 1627 1627 1627 1033 804 775 1263 21.60 2505 2468 1728 1728 1728 1035 779 789 1431 21.62 2331 2717 2003 2003 2003 1056 814 759 1586 21.64 2145 2955 2168 2168 2168 1069 785 805 1774 21.66 1921 3225 2560 2560 2560 1066 865 717 2088 21.68 1765 3371 2855 2855 2855 1027 934 710 2499 21.70 1503 3317 3125 3125 3125 1055 1047 740 2831 21.72 1244 3236 3151 3151 3151 1055 1312 717 3158 21.74 1132 2827 3145 3145 3145 1079 1731 737 3314 252 osr~f<^cNm^ooOfnTt>r>ococnr-or--fn—ivoo^oor- c so o 00 so i-< r- r- ©rN>/">t'-t-->oco>/-ir— ooosiooosou")-*'__ *.oocsmcsvooooo-nocsu-)Ovomoootso>ncSTtoo^H-- i o -1 O f » N t O • ..._.. _ t-~oooooooor-r^oooooooor-r- oooooor-oor~oor-oooooooooooor~oooo cncsooor~'*^vomooooooooooooot~-oo C3 CO CICIMMMNNHHH < a en p- os os —*osm^HOsoo^oor— [--r-coinoo -H o m in m so cs 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839 839 1030 709 707 881 23.80 831 812 879 879 879 949 716 698 819 23.82 876 829 891 891 891 995 718 686 877 23.84 827 821 898 898 898 1033 733 670 845 23.86 814 835 819 819 819 997 742 685 882 23.88 840 843 803 803 803 1001 743 727 836 23.90 870 859 825 825 825 961 742 697 850 23.92 865 820 815 815 815 958 683 718 787 23.94 853 841 804 804 804 983 732 694 837 23.96 885 879 819 819 819 1013 739 698 822 23.98 835 821 848 848 848 941 706 701 770 24.00 831 843 848 848 848 975 681 731 801 24.02 827 821 780 780 780 956 711 715 790 24.04 852 833 819 819 819 1009 740 725 803 24.06 821 881 823 823 823 997 709 681 783 24.08 820 851 829 829 829 982 705 701 762 24.10 903 908 795 795 795 977 733 682 759 24.12 839 943 806 806 806 989 712 659 777 24.14 884 969 791 791 791 996 697 695 733 24.16 910 1090 781 781 781 979 734 657 755 24.18 915 1133 813 813 813 979 716 695 775 24.20 923 1197 796 796 796 978 732 691 757 24.22 892 1243 834 834 834 1004 716 719 761 24.24 875 1259 799 799 799 984 791 752 770 24.26 887 1268 813 813 813 1003 717 661 715 24.28 923 1170 822 822 822 995 749 676 811 24.30 893 1022 775 775 775 964 711 683 783 24.32 875 984 796 796 796 941 803 685 725 24.34 869 904 804 804 804 1013 789 669 742 24.36 816 824 801 801 801 977 825 725 751 24.38 865 816 800 800 800 966 907 691 782 24.40 859 765 809 809 809 989 899 691 770 24.42 903 760 788 788 788 991 924 688 814 24.44 817 833 843 843 843 959 997 703 796 24.46 819 793 805 805 805 1012 1007 726 779 24.48 866 771 788 788 788 987 996 709 777 24.50 887 750 833 833 833 1024 1061 739 780 24.52 893 827 808 808 808 1025 1021 761 747 24.54 859 779 807 807 807 963 984 697 769 24.56 858 827 768 768 768 1014 981 716 747 24.58 858 777 817 817 817 993 915 726 803 24.60 915 785 831 831 831 998 863 711 761 24.62 899 857 827 827 827 955 855 739 772 255 N>MNiNiMMbJIOKiK)K)lv)IJIJK)K)KllOIOIOSJIOIONiK)IOK)IOMNlSlSISlN)KlNJNlNJK)KlK)IO M tO M tv) W M .p* 4*. -P.- -P» •£>• -P* Ul Ul Ul Ul Ul *. -p- o o bioio^owboobobobobo^^i -J ~J •-J ON ON ON 00 ON -P". tO © £ to © ©00ON4i.tO©00ON.p«.tO©00ON © oo ON -P* oo ON oo o\ A w ooo o\ oo ON -P* N> o V)0000SIV1NJV1-JS|00NIV|VJ00^^V|00VI0O00V1SISII!0VII!0^000000NIN|O000O000-.10000G000I!000(!000\OIXI \CUJ100*lO*Ul\OOOOvJO\U(»0\vlMvlOOO\>OOlNOOOO\OH'lj)vO(J|Hi(O^^OOOWU^OOO>«>C^^O S1VOUV1*0UIU\0O^U*IV1I-\00\^H'UI^USIV1U0\HV1OM00MV1UIU0000O\0*UIW>)^O*^-JM o sl-Jvl^^OO^vl-J-g-Jslvlvlvlvlvl-J-Jslvlsl-JOO-JsJvl-JvJOOOOslOOOOOONlvlOOOOOOOOvJOOvJMNlOOvl "3 00\WWtOO>Cvl-J*WVOvpaa^pNO^uvouim^iofw^^sw^^^^y^w^^^.^^^^w^^^^O^N^PSQooppO «NlOlvlvlW\00»0(»UlMvlUlUli-h.vlM^*^!>*vlUl»UUvlHUiUo l i— 5* ^vJsl^^slvlvl00vlvl0000-J00vlvl>lvlvl~Jv)O0>JvJOOO0l»O0O0O000000000tS00O0O0VO0O0O0O00vl00O0O0 >Ja«*00l/^>OHNlO\K)Ovlf-vllO11000\0Ul0\HOlO\H'HK)M^4iUis|vJ00H'\0l'll»Ma-J00Ul*K)HM ^^\0vlUlMt-MU\v0vlMMW0\v0vl\00\^W0\Ul^UOMU00OtOUlJii-Mln00AOOl^-J^.|i00Ui~J00 » to o* N1NJV]-J-JV1V1V1OO-J-JO0O0V)O0S|VJXISIVIV1SI00SI-J000000O0000O0000O000VOO0O0I»\O00OO00O0>J000O00 3 vi0\\0«00Ul^*Mxl0\IOO-jMv)*0000»0W(3iM0\ai-MMN^^Ul-Jvl00HN0Ul00i-0\-J00Ul«»0i-IO to ^Ji\0-JUMh-h-UL\0-jMMMO\\o>J*aMUO\Ui-WO^WC»OWl/i*M(JUi004iOa*-J**OOUlvlOO ON s v)vl-J-Jvl-JvlNlOOviNlOOOOvlOOvlvl^lvlsl>lv)OOvl-JI!0000000000000000000\0000000\OOOOOOOOOvlOOMOO sia\0*OOUl^*H'NlOMO-Ji-Nl\00000*UlO\^0\W^t-N)M.|i^Ul^~JOO^\OUlOOMO\-JOOUl*IOi-,M 3 ^^VOslUlMi-'i-'Ul*NlHHMO\VONl*Oii-UO\UlKUO>'UOOONUl^i-'|OUioO^Oa* 257 Gravity Gravity Blow Blow Blow Blow Aeration Aeration Aeration 28 1 2 1 2 3 4 1 2 3 26.56 943 746 787 787 787 2395 781 689 741 26.58 899 776 805 805 805 2592 786 639 745 26.60 900 798 847 847 847 2708 814 646 749 26.62 989 783 846 846 846 2856 877 669 774 26.64 984 785 838 838 838 3198 902 681 741 26.66 1040 768 813 813 813 3501 1000 663 752 26.68 1187 796 817 817 817 3808 990 651 777 26.70 1239 749 815 815 815 4274 1051 667 751 26.72 1496 839 901 901 901 4765 1068 702 768 26.74 1789 777 853 853 853 4899 1122 708 757 26.76 2337 832 861 861 861 5189 1179 684 795 26.78 2783 850 811 811 811 5327 1140 680 748 26.80 2971 884 856 856 856 5371 1113 705 811 26.82 3263 876 866 866 866 5499 1150 661 791 26.84 3437 931 873 873 873 5404 1097 717 826 26.86 3545 1000 858 858 858 5417 999 681 781 26.88 3550 1033 862 862 862 5307 1011 657 789 26.90 3579 1051 838 838 838 5298 977 661 818 26.92 3485 1114 835 835 835 4819 912 696 803 26.94 3523 1109 883 883 883 4661 839 696 847 26.96 3384 1155 934 934 934 4263 829 689 799 26.98 3465 1209 888 888 888 4029 763 640 819 27.00 3501 1283 942 942 942 3603 713 663 795 27.02 3541 1325 952 952 952 3137 733 673 796 27.04 3926 1453 977 977 977 2606 682 679 821 27.06 4200 1504 1042 1042 1042 2275 727 685 818 27.08 4593 1577 1093 1093 1093 1966 749 763 828 27.10 5217 1758 1265 1265 1265 1624 690 735 831 27.12 6129 1783 1427 1427 1427 1485 731 713 851 27.14 7491 2045 1689 1689 1689 1336 701 729 859 27.16 8667 2240 1963 1963 1963 1245 713 732 898 27.18 9682 2513 2199 2199 2199 1187 691 727 984 27.20 10547 2707 2507 2507 2507 1151 700 763 1000 27.22 10909 2922 2746 2746 2746 1067 704 739 1078 27.24 11391 3119 3034 3034 3034 1073 714 775 1123 27.26 11329 3377 3504 3504 3504 1065 701 741 1211 27.28 11237 3725 4045 4045 4045 1013 703 727 1403 27.30 10801 4010 4575 4575 4575 1042 713 734 1518 27.32 9711 4371 5179 5179 5179 1038 749 735 1616 27.34 8530 4603 6031 6031 6031 1082 713 717 1933 27.36 7005 4707 6770 6770 6770 1106 783 755 2482 27.38 5582 4759 7760 7760 7760 1272 829 713 3030 27.40 4145 5007 9029 9029 9029 1384 927 749 3533 27.42 3175 5015 10250 10250 10250 1549 983 726 4302 27.44 2299 4895 11135 11135 11135 1667 1032 734 5223 27.46 1621 4966 11895 11895 11895 1809 1083 747 6439 27.48 1345 4838 12339 12339 12339 1869 1115 707 7362 27.50 1127 4589 12095 12095 12095 1929 1135 750 8337 258 Gravity Gravity Blow Blow Blow Blow Aeration Aeration Aeration 20 1 2 1 2 3 4 1 2 3 27.52 1039 4453 11851 11851 11851 2012 1183 770 9216 27.54 975 3964 10880 10880 10880 1997 1221 743 9832 27.56 961 3741 9851 9851 9851 2005 1296 777 10527 27.58 935 3363 8545 8545 8545 1949 1337 775 11611 27.60 941 3129 7051 7051 7051 1795 1299 805 12619 27.62 905 2625 5473 5473 5473 1588 1440 835 13656 27.64 921 2394 4084 4084 4084 1504 1586 879 13191 27.66 912 2021 3067 3067 3067 1331 1940 933 10809 27.68 931 1664 2284 2284 2284 1203 2399 957 8000 27.70 904 1433 1611 1611 1611 1150 3071 1092 6381 27.72 852 1185 1222 1222 1222 1027 3794 1238 5053 27.74 852 1076 1073 1073 1073 1004 4533 1477 2909 27.76 879 979 976 976 976 970 5551 1682 1725 27.78 895 907 961 961 961 1000 6422 2131 1190 27.80 900 879 946 946 946 952 7452 2665 1097 27.82 840 839 973 973 973 959 8399 3473 975 27.84 881 918 967 967 967 973 9007 4983 915 27.86 863 880 872 872 872 1003 9229 6649 924 27.88 844 842 891 891 891 927 8935 8663 940 27.90 859 853 847 847 847 961 8637 10973 915 27.92 855 818 857 857 857 1040 7774 13159 820 27.94 873 885 855 855 855 1037 6829 14658 873 27.96 901 911 861 861 861 1103 6299 15732 835 27.98 903 875 853 853 853 1170 5508 16205 907 28.00 957 908 853 853 853 1121 4663 15799 869 28.02 980 901 857 857 857 1177 3488 14554 823 28.04 989 920 831 831 831 1177 2507 12835 853 28.06 999 924 839 839 839 1261 1966 11053 851 28.08 1049 975 860 860 860 1228 1561 9503 811 28.10 1037 951 843 843 843 1281 1041 7279 839 28.12 1067 960 874 874 874 1263 890 5103 834 28.14 1049 1010 892 892 892 1227 847 3706 828 28.16 1078 1016 884 884 884 1116 827 2685 831 28.18 1034 1013 977 977 977 1105 793 1940 887 28.20 990 957 1033 1033 1033 1067 784 1274 896 28.22 961 937 1151 1151 1151 1046 777 1068 866 28.24 863 1015 1195 1195 1195 975 722 909 837 28.26 916 920 1302 1302 1302 920 753 854 810 28.28 905 891 1299 1299 1299 919 771 872 821 28.30 853 831 1348 1348 1348 920 745 839 843 28.32 910 879 1353 1353 1353 882 744 853 825 28.34 843 893 1383 1383 1383 903 725 794 837 28.36 870 855 1325 1325 1325 920 760 788 800 28.38 815 839 1267 1267 1267 871 776 809 793 28.40 817 847 1192 1192 1192 845 727 805 827 28.42 953 802 1195 1195 1195 900 779 757 840 28.44 961 820 1080 1080 1080 843 883 771 827 28.46 1105 857 1034 1034 1034 909 934 739 821 259 Gravity Gravity Blow Blow Blow Blow Aeration Aeration Aeration 29 1 2 1 2 3 4 1 2 3 28.48 1262 817 1015 1015 1015 865 913 757 802 28.50 1638 829 1070 1070 1070 874 945 763 827 28.52 1941 841 1129 1129 1129 871 998 708 783 28.54 1960 845 1380 1380 1380 916 963 773 844 28.56 2154 859 1948 1948 1948 828 1026 731 801 28.58 2204 835 2795 2795 2795 887 974 683 800 28.60 2169 829 3675 3675 3675 873 1027 743 809 28.62 2142 865 4163 4163 4163 888 999 714 802 28.64 1999 767 4627 4627 4627 881 994 715 781 28.66 1850 823 4786 4786 4786 865 1005 759 806 28.68 1739 845 4811 4811 4811 838 1011 767 816 28.70 1461 789 4684 4684 4684 829 964 703 807 28.72 1269 783 4381 4381 4381 837 937 709 771 28.74 1134 774 3935 3935 3935 821 934 731 785 28.76 1069 779 3257 3257 3257 849 901 749 771 28.78 986 791 2935 2935 2935 860 842 743 809 28.80 907 761 2308 2308 2308 890 808 771 805 28.82 840 723 1989 1989 1989 867 858 715 795 28.84 837 755 1589 1589 1589 887 769 760 768 28.86 851 747 1420 1420 1420 827 763 745 771 28.88 834 763 1181 1181 1181 825 743 698 789 28.90 825 739 1047 1047 1047 851 739 761 758 28.92 819 751 1039 1039 1039 867 741 708 755 28.94 853 737 1016 1016 1016 827 739 731 737 28.96 855 799 981 981 981 817 723 697 745 28.98 856 769 979 979 979 871 711 753 744 29.00 819 764 1005 1005 1005 901 735 748 789 29.02 795 738 1047 1047 1047 859 757 751 734 29.04 788 763 1015 1015 1015 823 735 699 715 29.06 827 733 1003 1003 1003 847 721 692 745 29.08 744 804 967 967 967 831 705 693 749 29.10 730 767 1014 1014 1014 894 725 705 729 29.12 747 752 967 967 967 863 710 715 719 29.14 806 735 997 997 997 875 683 743 751 29.16 736 731 949 949 949 825 703 725 727 29.18 736 740 914 914 914 812 717 729 717 29.20 707 749 857 857 857 810 700 727 749 29.22 757 747 833 833 833 824 652 709 718 29.24 763 691 797 797 797 847 690 729 703 29.26 729 715 777 777 777 851 688 687 692 29.28 737 720 788 788 788 851 699 713 756 29.30 789 689 817 817 817 827 658 719 735 29.32 743 721 788 788 788 833 681 712 707 29.34 761 706 767 767 767 823 663 751 721 29.36 741 730 794 794 794 819 695 688 756 29.38 763 742 793 793 793 827 703 680 716 29.40 766 746 765 765 765 796 657 706 719 29.42 767 792 724 724 724 823 658 672 699 260 Gravity Gravity Blow Blow Blow Blow ,Aeratio n ,Aeratio n Aeration 20 1 2 1 2 3 4 1 2 3 29.44 785 744 746 746 746 828 684 724 742 29.46 782 700 819 819 819 829 675 663 680 29.48 729 704 773 773 773 825 709 712 685 29.50 749 711 744 744 744 853 611 655 707 29.52 787 752 727 727 727 850 716 667 741 29.54 744 767 763 763 763 831 664 649 719 29.56 706 683 720 720 720 847 642 712 736 29.58 725 709 752 752 752 821 675 695 724 29.60 725 729 739 739 739 847 655 695 705 29.62 769 721 727 727 727 851 663 703 734 29.64 733 738 764 764 764 833 696 687 750 29.66 740 749 765 765 765 823 681 681 716 29.68 749 713 713 713 713 860 674 649 723 29.70 765 719 712 712 712 861 634 631 710 29.72 725 744 769 769 769 838 664 688 721 29.74 764 696 727 727 727 852 621 649 711 29.76 734 742 739 739 739 826 651 640 687 29.78 751 725 761 761 761 819 635 679 725 29.80 735 714 737 737 737 840 644 659 729 29.82 740 695 768 768 768 797 673 659 741 29.84 767 723 718 718 718 815 657 679 749 29.86 715 705 769 769 769 829 663 661 688 29.88 787 726 715 715 715 833 678 632 719 29.90 734 719 764 764 764 801 669 657 723 29.92 721 695 745 745 745 803 664 631 743 29.94 740 725 711 711 711 817 681 687 772 29.96 763 707 737 737 737 833 637 639 738 29.98 737 691 720 720 720 875 609 659 701 30.00 722 681 736 736 736 793 653 671 720 30.02 734 745 740 740 740 763 629 680 699 30.04 729 733 748 748 748 822 656 649 704 30.06 731 741 731 731 731 807 681 641 693 30.08 751 745 748 748 748 779 639 643 659 30.10 794 727 763 763 763 799 613 649 715 30.12 715 728 712 712 712 791 661 631 723 30.14 755 762 753 753 753 780 669 662 708 30.16 734 715 682 682 682 816 653 646 692 30.18 689 721 724 724 724 805 663 656 715 30.20 729 763 688 688 688 791 648 660 679 30.22 712 726 783 783 783 799 654 615 683 30.24 734 733 761 761 761 781 641 627 697 30.26 707 755 779 779 779 809 665 623 715 30.28 705 741 780 780 780 793 632 649 723 30.30 747 729 824 824 824 810 661 630 683 30.32 721 735 779 779 779 784 684 657 721 30.34 707 743 791 791 791 797 623 673 691 30.36 718 741 799 799 799 787 658 655 667 30.38 722 719 755 755 755 773 627 663 672 261 Gravity Gravity Blow Blow Blow Blow deration *deratio n Aeration 29 1 2 1 2 3 4 1 2 3 30.40 736 717 755 755 755 751 674 623 684 30.42 728 718 796 796 796 806 639 662 710 30.44 733 708 717 717 717 777 653 611 717 30.46 712 687 743 743 743 807 682 598 692 30.48 725 722 742 742 742 793 783 648 671 30.50 727 681 730 730 730 808 825 637 649 30.52 667 739 714 714 714 790 781 623 683 30.54 703 685 737 737 737 752 837 655 644 30.56 682 702 722 722 722 787 879 591 690 30.58 690 707 679 679 679 751 893 615 705 30.60 698 749 709 709 709 799 891 646 693 30.62 697 693 699 699 699 757 843 639 657 30.64 693 734 757 757 757 805 884 649 665 30.66 705 735 657 657 657 787 819 656 705 30.68 731 710 722 722 722 729 789 631 644 30.70 701 689 715 715 715 737 755 653 685 30.72 716 665 719 719 719 807 745 608 653 30.74 717 670 695 695 695 736 721 629 689 30.76 721 730 710 710 710 798 706 638 688 30.78 717 711 725 725 725 817 725 652 675 30.80 704 737 739 739 739 741 671 639 667 30.82 696 725 717 717 717 745 614 628 697 30.84 659 777 714 714 714 785 659 654 701 30.86 692 767 688 688 688 761 636 663 660 30.88 726 746 689 689 689 777 639 659 727 30.90 703 760 738 738 738 797 664 628 658 30.92 703 801 699 699 699 766 680 637 679 30.94 703 755 711 711 711 742 658 615 641 30.96 702 780 699 699 699 751 623 643 657 30.98 689 762 715 715 715 759 667 654 663 31.00 664 828 709 709 709 771 635 617 688 31.02 694 785 717 717 717 764 645 612 710 31.04 720 767 706 706 706 788 663 637 667 31.06 660 761 732 732 732 771 653 634 695 31.08 691 738 743 743 743 737 607 661 689 31.10 715 756 713 713 713 699 622 649 729 31.12 651 698 697 697 697 741 628 593 717 31.14 658 769 675 675 675 736 596 635 721 31.16 701 694 649 649 649 767 626 616 743 31.18 678 691 700 700 700 789 637 603 702 31.20 709 683 659 659 659 742 601 625 697 31.22 686 754 677 677 677 750 632 645 760 31.24 675 766 661 661 661 737 623 585 725 31.26 662 744 658 658 658 729 579 606 793 31.28 719 753 672 672 672 722 632 592 855 31.30 695 769 687 687 687 757 633 625 928 31.32 703 789 686 686 686 730 649 611 926 31.34 720 749 679 679 679 725 589 613 948 262 Gravity Gravity Blow Blow Blow Blow Jderatio n J deration ,deratio n 29 1 2 1 2 3 4 1 2 3 31.36 706 769 673 673 673 755 607 605 969 31.38 731 777 641 641 641 719 608 629 979 31.40 733 785 691 691 691 695 611 651 980 31.42 733 759 655 655 655 705 620 639 943 31.44 739 748 643 643 643 727 609 607 892 31.46 737 697 661 661 661 699 607 596 881 31.48 717 686 693 693 693 781 597 638 842 31.50 713 708 673 673 673 747 576 613 785 31.52 743 710 649 649 649 723 607 611 748 31.54 699 703 630 630 630 711 607 608 793 31.56 707 702 685 685 685 695 587 602 759 31.58 731 714 628 628 628 746 598 567 697 31.60 706 707 669 669 669 711 580 620 709 31.62 717 675 620 620 620 697 573 635 711 31.64 662 644 661 661 661 749 619 631 766 31.66 638 690 645 645 645 711 606 621 687 31.68 657 675 693 693 693 722 587 580 735 31.70 697 668 630 630 630 727 571 617 721 31.72 669 696 631 631 631 775 585 587 785 31.74 664 698 661 661 661 718 611 623 777 31.76 646 661 626 626 626 715 595 616 775 31.78 684 629 671 671 671 721 622 619 771 31.80 697 632 701 701 701 697 627 627 770 31.82 653 641 649 649 649 763 611 628 737 31.84 649 653 662 662 662 734 619 609 732 31.86 647 635 651 651 651 709 613 605 723 31.88 649 623 643 643 643 735 599 589 772 31.90 645 669 651 651 651 725 553 592 717 31.92 665 637 648 648 648 746 563 617 660 31.94 659 638 645 645 645 711 576 630 671 31.96 637 643 663 663 663 729 606 616 702 31.98 678 649 653 653 653 751 569 600 662 32.00 638 648 606 606 606 716 596 606 637 32.02 642 630 652 652 652 727 589 634 611 32.04 616 655 655 655 655 711 599 613 641 32.06 639 634 643 643 643 742 611 621 700 32.08 648 673 622 622 622 709 580 589 631 32.10 629 616 667 667 667 717 593 587 633 32.12 675 649 647 647 647 716 593 629 614 32.14 649 617 616 616 616 686 553 636 644 32.16 638 664 616 616 616 713 563 583 645 32.18 629 616 626 626 626 684 575 624 623 32.20 646 633 615 615 615 742 587 608 623 32.22 643 588 634 634 634 713 587 618 667 32.24 624 602 593 593 593 725 589 602 633 32.26 637 656 659 659 659 704 581 615 593 32.28 617 638 622 622 622 711 556 636 638 32.30 627 636 669 669 669 709 567 583 649 263 Gravity Gravity Blow Blow Blow Blow Aeration ideratio n Aeration 20 1 2 1 2 3 4 1 2 3 32.32 627 625 657 657 657 714 567 572 625 32.34 585 589 622 622 622 769 580 614 589 32.36 630 617 635 635 635 721 564 573 667 32.38 611 645 629 629 629 767 563 580 613 32.40 609 641 678 678 678 724 590 614 574 32.42 662 649 634 634 634 723 580 553 622 32.44 635 623 627 627 627 746 563 586 591 32.46 675 633 649 649 649 719 591 591 583 32.48 649 607 620 620 620 761 558 597 607 32.50 654 599 589 589 589 734 572 589 609 32.52 629 622 619 619 619 736 593 561 630 32.54 639 624 611 611 611 710 550 580 603 32.56 657 634 638 638 638 739 553 576 628 32.58 640 603 638 638 638 720 552 587 598 32.60 647 621 596 596 596 673 554 563 617 32.62 668 615 573 573 573 682 573 560 639 32.64 675 608 611 611 611 699 551 585 633 32.66 638 589 640 640 640 720 567 614 627 32.68 645 605 593 593 593 735 549 579 630 32.70 653 635 611 611 611 681 588 566 605 32.72 623 629 611 611 611 663 591 541 595 32.74 641 599 639 639 639 656 603 553 615 32.76 625 605 595 595 595 665 539 600 591 32.78 633 627 620 620 620 673 556 575 635 32.80 624 624 623 623 623 686 601 587 655 32.82 613 608 615 615 615 671 567 567 605 32.84 618 627 584 584 584 680 585 572 599 32.86 623 639 620 620 620 698 558 555 628 32.88 632 615 612 612 612 686 559 603 604 32.90 621 615 635 635 635 679 610 562 595 32.92 622 598 676 676 676 689 545 552 607 32.94 596 629 647 647 647 667 543 583 639 32.96 606 645 611 611 611 665 557 582 609 32.98 655 630 597 597 597 663 539 572 595 33.00 627 645 661 661 661 751 545 564 591 33.02 641 625 606 606 606 677 531 551 611 33.04 601 638 620 620 620 694 553 559 587 33.06 614 610 600 600 600 710 559 562 632 33.08 623 574 597 597 597 680 557 559 607 33.10 623 606 622 622 622 674 561 577 619 33.12 626 600 599 599 599 707 563 585 594 33.14 609 570 612 612 612 698 553 594 633 33.16 614 593 628 628 628 653 573 579 620 33.18 607 585 597 597 597 649 557 572 653 33.20 601 590 593 593 593 712 565 579 625 33.22 593 613 579 579 579 679 544 548 583 33.24 589 617 579 579 579 725 557 568 593 33.26 593 593 636 636 636 649 591 555 643 264 Gravity Gravity Blow Blow Blow Blow Aeration Aeration Aeration 29 1 2 1 2 3 4 1 2 3 33.28 618 604 622 622 622 707 580 557 610 33.30 599 579 621 621 621 635 544 584 595 33.32 619 595 585 585 585 688 609 535 562 33.34 585 605 612 612 612 675 561 522 577 33.36 615 587 617 617 617 671 586 576 562 33.38 598 593 616 616 616 720 567 577 623 33.40 599 575 638 638 638 644 607 563 577 33.42 608 578 580 580 580 678 604 575 563 33.44 651 617 609 609 609 654 614 559 623 33.46 598 594 590 590 590 703 595 549 601 33.48 599 607 628 628 628 679 605 565 613 33.50 626 632 587 587 587 642 593 554 567 33.52 635 600 594 594 594 669 600 585 585 33.54 593 599 603 603 603 683 601 537 615 33.56 629 641 568 568 568 640 646 578 573 33.58 583 585 591 591 591 672 631 554 596 33.60 593 599 547 547 547 683 596 586 591 33.62 599 611 606 606 606 643 594 556 582 33.64 589 615 575 575 575 684 656 593 589 33.66 625 604 598 598 598 677 638 581 605 33.68 601 621 623 623 623 629 650 579 574 33.70 618 611 597 597 597 676 661 491 609 33.72 615 618 591 591 591 665 614 591 590 33.74 609 565 623 623 623 676 659 573 602 33.76 583 621 603 603 603 634 614 564 587 33.78 620 601 626 626 626 665 613 563 584 33.80 591 579 611 611 611 681 578 531 591 33.82 604 573 597 597 597 624 604 530 547 33.84 585 606 604 604 604 657 567 592 598 33.86 585 593 592 592 592 672 537 570 582 33.88 594 594 567 567 567 661 597 559 609 33.90 603 615 632 632 632 674 567 542 591 33.92 551 640 590 590 590 666 535 554 611 33.94 578 563 596 596 596 649 555 551 608 33.96 599 581 591 591 591 691 538 553 579 33.98 606 579 592 592 592 659 560 533 610 34.00 538 581 624 624 624 639 566 571 555 34.02 556 559 594 594 594 649 550 552 563 34.04 607 581 570 570 570 671 573 545 569 34.06 565 583 621 621 621 647 521 519 591 34.08 570 594 560 560 560 652 561 567 608 34.10 573 586 563 563 563 647 545 556 564 34.12 573 589 599 599 599 697 525 560 562 34.14 612 575 530 530 530 659 567 552 598 34.16 582 546 578 578 578 650 583 608 563 34.18 603 573 563 563 563 631 543 551 585 34.20 569 586 568 568 568 665 544 567 556 34.22 587 571 562 562 562 665 542 590 567 265 Gravity Gravity Blow Blow Blow Blow J deration Aeration ,deratio n 20 1 2 1 2 3 4 1 2 3 34.24 591 583 593 593 593 669 547 583 545 34.26 575 588 583 583 583 683 569 564 586 34.28 543 557 583 583 583 623 537 577 605 34.30 579 582 560 560 560 643 561 587 563 34.32 573 565 582 582 582 664 543 582 601 34.34 571 552 580 580 580 651 549 577 576 34.36 565 603 533 533 533 676 551 593 531 34.38 569 574 579 579 579 625 519 554 599 34.40 579 578 573 573 573 629 521 562 575 34.42 601 571 534 534 534 673 559 536 584 34.44 575 561 547 547 547 693 546 513 581 34.46 579 545 583 583 583 669 535 545 567 34.48 558 571 573 573 573 710 523 545 561 34.50 545 599 567 567 567 662 539 555 557 34.52 597 539 577 577 577 707 518 547 576 34.54 569 580 563 563 563 713 547 531 563 34.56 555 565 584 584 584 708 527 525 582 34.58 553 534 571 571 571 721 540 545 577 34.60 584 565 573 573 573 709 529 538 576 34.62 607 553 595 595 595 714 534 526 521 34.64 585 566 577 577 577 693 534 519 575 34.66 574 563 561 561 561 709 495 526 525 34.68 577 543 581 581 581 677 525 577 541 34.70 612 562 573 573 573 677 545 573 571 34.72 603 554 575 575 575 671 532 537 583 34.74 597 611 585 585 585 683 543 505 581 34.76 557 600 585 585 585 695 467 539 566 34.78 587 567 591 591 591 694 513 527 583 34.80 591 567 575 575 575 670 539 562 585 34.82 563 601 563 563 563 664 513 544 576 34.84 631 574 555 555 555 676 526 523 568 34.86 603 597 581 581 581 711 526 532 541 34.88 587 572 597 597 597 679 532 509 573 34.90 573 570 617 617 617 671 509 541 596 34.92 550 537 603 603 603 656 520 541 545 34.94 574 527 633 633 633 651 527 557 574 34.96 603 597 636 636 636 684 512 543 569 34.98 612 595 637 637 637 705 514 547 530 35.00 577 575 616 616 616 701 536 539 579 35.02 583 558 643 643 643 700 551 530 527 35.04 579 558 636 636 636 667 515 547 553 35.06 606 595 668 668 668 685 496 535 577 35.08 591 593 657 657 657 677 493 533 557 35.10 620 598 625 625 625 715 509 525 545 35.12 581 560 630 630 630 709 519 540 559 35.14 553 583 654 654 654 688 535 525 583 35.16 567 555 644 644 644 698 546 548 573 35.18 591 593 600 600 600 695 538 546 543 266 Gravity Gravity Blow Blow Blow Blow Aeration Aeration Aeration 29 1 2 12 3 4 12 3 35.20 605 599 623 623 623 733 527 521 571 35.22 606 545 613 613 613 676 544 564 579 35.24 621 607 586 586 586 666 532 576 565 35.26 617 578 609 609 609 685 530 524 577 35.28 629 550 593 593 593 658 515 569 582 35.30 636 586 591 591 591 703 525 564 606 35.32 627 553 573 573 573 659 527 530 605 35.34 607 572 581 581 581 690 511 557 566 35.36 611 584 577 577 577 689 511 537 578 35.38 621 610 589 589 589 735 533 547 577 35.40 604 555 579 579 579 689 521 514 637 35.42 613 595 595 595 595 688 536 556 592 35.44 647 585 579 579 579 690 515 540 578 35.46 636 632 593 593 593 693 523 580 591 35.48 630 633 606 606 606 657 537 567 614 35.50 645 579 634 634 634 703 511 552 581 35.52 657 607 613 613 613 745 505 565 594 35.54 635 641 601 601 601 708 517 558 585 35.56 641 615 637 637 637 683 552 561 612 35.58 663 603 607 607 607 711 560 569 573 35.60 655 602 599 599 599 739 535 592 589 35.62 681 587 610 610 610 693 513 615 617 35.64 711 569 626 626 626 703 569 639 620 35.66 723 646 645 645 645 666 548 593 582 35.68 742 593 625 625 625 677 535 632 605 35.70 716 631 631 631 631 683 561 627 573 35.72 701 614 577 577 577 700 531 605 612 35.74 691 604 637 637 637 669 529 597 602 35.76 700 595 583 583 583 665 572 595 607 35.78 694 625 600 600 600 691 545 571 583 35.80 689 578 619 619 619 731 566 589 599 35.82 731 609 656 656 656 702 562 559 613 35.84 742 630 629 629 629 729 566 597 605 35.86 712 588 615 615 615 710 581 593 593 35.88 747 613 630 630 630 724 593 639 611 35.90 735 581 623 623 623 727 577 577 547 35.92 739 599 641 641 641 792 567 604 577 35.94 707 622 633 633 633 834 579 577 616 35.96 693 599 579 579 579 811 510 536 581 35.98 727 587 623 623 623 832 533 569 612 36.00 688 591 555 555 555 781 569 603 574 36.02 719 594 607 607 607 758 551 569 623 36.04 685 577 599 599 599 748 563 562 593 36.06 693 611 614 614 614 709 526 565 579 36.08 682 553 618 618 618 700 549 532 625 36.10 695 610 604 604 604 667 589 530 617 36.12 675 594 581 581 581 709 545 561 573 36.14 665 601 562 562 562 638 545 554 583 267 Gravity Gravity Blow Blow Blow Blow Aeration Aeration Aeration 29 1 2 1 2 3 4 1 2 3 36.16 636 615 603 603 603 690 576 560 592 36.18 615 639 621 621 621 659 556 596 583 36.20 649 639 642 642 642 693 548 589 595 36.22 648 612 603 603 603 703 552 555 605 36.24 649 599 647 647 647 691 559 554 625 36.26 663 595 618 618 618 679 546 538 608 36.28 649 628 664 664 664 710 571 601 639 36.30 672 605 649 649 649 691 535 587 607 36.32 593 635 685 685 685 704 549 577 653 36.34 650 578 698 698 698 679 555 554 623 36.36 595 591 702 702 702 734 556 565 659 36.38 629 607 685 685 685 701 545 556 629 36.40 688 638 673 673 673 701 594 582 641 36.42 646 595 638 638 638 737 569 577 585 36.44 609 577 626 626 626 705 608 575 604 36.46 629 614 670 670 670 751 592 573 570 36.48 611 600 667 667 667 819 571 599 649 36.50 625 619 582 582 582 824 572 578 620 36.52 627 579 624 624 624 825 524 575 639 36.54 627 585 611 611 611 891 589 554 646 36.56 639 580 621 621 621 1019 569 567 612 36.58 641 616 585 585 585 1075 573 563 615 36.60 567 571 586 586 586 1105 591 563 575 36.62 624 596 604 604 604 1161 611 542 639 36.64 631 580 621 621 621 1194 584 506 608 36.66 642 614 619 619 619 1289 643 602 587 36.68 582 604 603 603 603 1351 623 586 607 36.70 602 577 571 571 571 1368 699 559 617 36.72 655 576 591 591 591 1360 745 606 574 36.74 677 615 579 579 579 1305 829 623 604 36.76 697 627 604 604 604 1318 879 573 589 36.78 761 578 589 589 589 1278 857 587 581 36.80 784 635 599 599 599 1244 945 579 600 36.82 779 575 601 601 601 1185 1019 617 553 36.84 857 619 579 579 579 1099 975 577 599 36.86 907 619 604 604 604 1032 1067 582 581 36.88 915 596 595 595 595 947 1034 584 619 36.90 926 639 611 611 611 880 1007 611 609 36.92 975 603 574 574 574 861 888 624 607 36.94 1028 641 598 598 598 771 821 619 605 36.96 1075 598 580 580 580 777 798 607 618 36.98 1222 627 595 595 595 762 704 649 601 37.00 1408 589 622 622 622 687 661 623 605 37.02 1653 625 610 610 610 680 637 665 595 37.04 1895 611 622 622 622 672 575 679 622 37.06 2214 633 611 611 611 675 586 823 596 37.08 2447 679 595 595 595 651 541 927 647 37.10 2730 703 618 618 618 635 541 1059 620 268 Gravity Gravity Blow Blow Blow Blow Aeration Aeration Aeration 29 1 2 1 2 3 4 1 2 3 37.12 3187 689 645 645 645 636 553 1084 631 37.14 3497 717 665 665 665 637 563 1026 625 37.16 3505 741 737 737 737 598 536 872 640 37.18 3465 825 758 758 758 633 592 837 646 37.20 3301 863 835 835 835 640 532 844 664 37.22 2915 859 866 866 866 620 560 777 683 37.24 2679 909 916 916 916 614 527 688 733 37.26 2419 928 1005 1005 1005 587 550 651 797 37.28 2238 908 1186 1186 1186 607 559 595 938 37.30 1810 952 1187 1187 1187 617 543 561 999 37.32 1403 901 1267 1267 1267 580 582 535 1135 37.34 1156 917 1277 1277 1277 614 567 602 1258 37.36 969 873 1247 1247 1247 604 548 578 1359 37.38 909 862 1307 1307 1307 633 596 561 1381 37.40 814 854 1285 1285 1285 599 613 541 1505 37.42 686 810 1183 1183 1183 607 640 591 1489 37.44 625 755 1099 1099 1099 596 652 592 1555 37.46 596 713 1029 1029 1029 629 693 549 1463 37.48 577 665 929 929 929 613 799 603 1401 37.50 605 667 821 821 821 592 844 583 1354 37.52 607 646 785 785 785 637 820 547 1257 37.54 563 586 729 729 729 610 905 590 1088 37.56 541 626 681 681 681 625 899 595 963 37.58 558 563 617 617 617 571 1033 606 877 37.60 565 590 603 603 603 618 1107 663 787 37.62 537 539 616 616 • 616 597 1186 667 714 37.64 565 558 583 583 583 597 1263 739 659 37.66 581 561 573 573 573 625 1264 832 605 37.68 569 534 549 549 549 619 1277 885 623 37.70 564 596 555 555 555 586 1355 1021 601 37.72 549 515 565 565 565 603 1409 1260 559 37.74 529 571 513 513 513 594 1335 1712 603 37.76 569 555 580 580 580 591 1288 2285 573 37.78 560 588 543 543 543 589 1241 2661 568 37.80 539 553 553 553 553 596 1101 2963 549 37.82 552 504 516 516 516 595 1017 3221 572 37.84 521 518 557 557 557 579 898 3354 574 37.86 565 550 531 531 531 635 859 3609 589 37.88 575 537 571 571 571 557 736 3619 546 37.90 542 555 543 543 543 583 647 3535 559 37.92 579 558 562 562 562 618 604 3583 558 37.94 545 517 539 539 539 573 633 3198 539 37.96 577 553 508 508 508 587 550 2691 536 37.98 545 551 541 541 541 575 558 2087 529 38.00 536 518 513 513 513 543 495 1692 542 38.02 575 559 537 537 537 598 517 1556 558 38.04 556 527 515 515 515 609 559 1291 504 38.06 536 555 519 519 519 621 553 1085 525 269 Gravity Gravity Blow Blow Blow Blow Aeration Aeration Aeration 26 1 2 12 3 4 12 3 38.08 596 535 503 503 503 553 459 786 527 38.10 585 531 525 525 525 604 523 692 555 38.12 610 533 530 530 530 605 508 603 520 38.14 594 536 501 501 501 556 495 603 535 38.16 588 542 531 531 531 612 525 598 509 38.18 621 555 562 562 562 605 551 583 507 38.20 645 466 528 528 528 571 508 553 564 38.22 644 577 527 527 527 591 509 577 545 38.24 683 559 523 523 523 611 527 569 542 38.26 651 539 513 513 513 577 533 564 524 38.28 693 562 523 523 523 574 515 529 540 38.30 690 525 547 547 547 566 510 537 539 38.32 707 531 559 559 559 627 493 525 545 38.34 716 531 533 533 533 577 490 533 549 38.36 721 531 564 564 564 587 517 521 558 38.38 722 553 499 499 499 575 515 545 569 38.40 716 555 503 503 503 572 505 521 516 38.42 709 558 503 503 503 541 488 490 508 38.44 691 542 528 528 528 578 484 550 557 38.46 634 549 552 552 552 608 516 557 545 38.48 662 525 573 573 573 588 509 550 572 38.50 621 501 519 519 519 586 509 536 528 38.52 609 506 533 533 533 567 526 527 522 38.54 612 508 506 506 506 603 497 491 523 38.56 591 517 533 533 533 581 497 565 565 38.58 585 505 526 526 526 610 495 550 545 38.60 538 527 566 566 566 636 520 517 535 38.62 546 547 511 511 511 641 508 520 543 530 526 38.64 506 526 526 619 506 545 545 517 523 38.66 521 523 523 676 524 542 501 517 505 38.68 530 505 505 657 505 519 547 501 529 38.70 541 529 529 713 517 525 523 38.72 561 544 525 525 525 674 517 541 538 38.74 498 515 515 515 515 713 506 533 533 38.76 519 524 513 513 513 721 453 540 521 38.78 553 529 511 511 511 695 481 507 529 38.80 522 511 525 525 525 706 517 536 545 38.82 558 545 474 474 474 701 495 521 519 38.84 532 553 503 503 503 673 483 497 517 38.86 515 515 503 503 503 649 510 525 503 38.88 531 483 497 497 497 629 507 516 528 38.90 532 539 537 537 537 609 508 489 530 38.92 520 549 534 534 534 593 523 527 550 38.94 511 521 514 514 514 583 483 530 517 38.96 533 513 523 523 523 565 505 507 537 38.98 522 523 523 523 523 583 519 541 521 39.00 526 520 569 569 569 605 485 531 532 39.02 523 519 559 559 559 573 466 478 528 270 c r-^HSooinoooooo-H —< oo oo © -H in co o ^•in^tinmininin,'*minm^-Tfmm>nin ca en u < - oo©inasmsoosin-H— 0^oOTta3c^i»oora\or~Osw^w^Ot~OOcnt~r^r4^^i»^r^r c-)r~r~rt^rtc^r~fno\r~vor^o\^oocnoo\c^vooKu^r^r~cn<^t~(^rju^cnu^r40NC4vort^oc~^o^fnfnoN cnvoootsoo^cso\OOOst-~cnrnooOrtCSO'-iO\0\rn(Srn(SO\\ootso--tS'^-- « c^r~c~^in^rNir~coost^vor^ON^©©rn©ONC^voos>nesr~roo\c~a\rNiincoinc^osc^so^ino r-» rf O so O en Os rnvo(X)r^ooos(sa\ooosr~-cnc<-iooO'-Hcso-HO\ONrntsrocsos^oC)tsO'-'tS'-'-Hcnooo r- o o o\ rr is ts * m m * m m in s rat~t^^>n^r^r^fnost~vDr~osvDOOcno^r^voi^iritsp~cnosr~o\tsiocnintsosts^£)^Hino r~ Tt o so m ro o\ r- O O Os Tt CS CN cnvO00CSOO0NC4O\OO0sr--mcnOOO'^tSO-^0\0Ncn 272 Gravity Gravity Blow Blow Blow Blow Jderatio n Aeration ,deratio n 29 1 2 1 2 3 4 1 2 3 40.96 958 992 600 600 600 515 492 514 525 40.98 938 962 641 641 641 546 477 483 569 41.00 916 985 613 613 613 524 482 509 569 41.02 929 958 694 694 694 536 513 485 613 41.04 850 952 748 748 748 518 478 495 673 41.06 723 953 747 747 747 478 508 482 754 41.08 705 841 776 776 776 523 495 498 769 41.10 632 881 778 778 778 547 471 494 807 41.12 666 748 757 757 757 505 495 471 808 41.14 583 737 768 768 768 550 484 495 861 41.16 527 718 759 759 759 554 502 489 947 41.18 509 647 728 728 728 521 465 499 926 41.20 513 628 690 690 690 551 522 489 962 41.22 494 592 697 697 697 553 524 486 912 41.24 495 555 660 660 660 542 535 506 845 41.26 503 551 590 590 590 562 575 485 763 41.28 519 504 575 575 575 599 578 524 705 41.30 483 514 541 541 541 532 631 498 651 41.32 518 515 521 521 521 524 651 539 642 41.34 498 503 493 493 493 513 711 520 629 41.36 482 532 522 522 522 533 725 551 578 41.38 495 507 497 497 497 520 754 593 543 41.40 477 501 479 479 479 579 777 616 513 41.42 463 483 483 483 483 527 761 631 505 41.44 504 488 495 495 495 507 813 675 488 41.46 467 517 473 473 473 539 789 746 520 41.48 493 525 477 477 477 534 762 886 483 41.50 487 511 459 459 459 537 736 944 500 41.52 495 547 475 475 475 515 681 921 489 41.54 492 540 465 465 465 527 680 917 501 41.56 511 517 489 489 489 517 645 1005 471 41.58 485 513 489 489 489 510 574 1021 493 41.60 464 547 501 501 501 503 561 1006 487 41.62 508 533 464 464 464 503 537 949 512 41.64 490 523 514 514 514 509 517 871 493 41.66 507 522 533 533 533 533 485 783 495 41.68 495 529 491 491 491 531 507 765 506 41.70 494 479 469 469 469 520 497 731 473 41.72 481 502 487 487 487 502 484 651 468 41.74 495 514 460 460 460 534 475 631 479 41.76 475 511 466 466 466 526 491 569 510 41.78 485 511 477 477 477 519 463 561 487 41.80 484 527 442 442 442 535 502 515 505 41.82 469 537 465 465 465 552 484 512 473 41.84 474 553 489 489 489 499 480 521 485 41.86 489 532 488 488 488 512 475 500 460 41.88 486 525 485 485 485 529 489 479 471 41.90 505 557 495 495 495 517 463 483 508 273 Gravity Gravity Blow Blow Blow Blow Aeration Aeration Aeration 29 1 2 1 2 3 4 1 2 3 41.92 500 542 460 460 460 529 483 523 473 41.94 461 551 446 446 446 540 487 470 471 41.96 468 554 495 495 495 517 462 476 473 41.98 458 529 478 478 478 535 501 501 491 42.00 467 531 479 479 479 522 461 494 529 42.02 469 506 488 488 488 543 485 497 453 42.04 504 477 465 465 465 535 479 505 493 42.06 431 497 472 472 472 514 466 489 469 42.08 480 495 495 495 495 549 488 478 440 42.10 481 492 469 469 469 503 466 493 464 42.12 519 481 458 458 458 530 470 471 508 42.14 509 442 469 469 469 552 483 522 488 42.16 488 479 461 461 461 527 449 478 482 42.18 480 472 466 466 466 534 467 476 471 42.20 498 481 471 471 471 547 485 485 490 42.22 478 513 470 470 470 511 473 465 478 42.24 511 490 487 487 487 534 466 458 467 42.26 529 503 476 476 476 541 425 443 490 42.28 475 519 458 458 458 569 488 483 491 42.30 504 461 441 441 441 577 461 489 483 42.32 465 496 475 475 475 591 480 483 483 42.34 513 490 476 476 476 568 431 481 482 42.36 487 488 463 463 463 581 501 495 473 42.38 469 481 471 471 471 627 441 460 477 42.40 503 449 477 477 477 642 461 484 468 42.42 479 462 469 469 469 661 426 476 507 42.44 493 491 450 450 450 657 453 456 465 42.46 493 483 489 489 489 723 453 511 511 42.48 494 486 519 519 519 781 421 475 496 42.50 491 452 485 485 485 851 511 492 486 42.52 465 479 461 461 461 913 431 480 463 42.54 483 502 465 465 465 973 464 489 477 42.56 485 506 465 465 465 955 455 450 490 42.58 469 495 499 499 499 985 470 473 475 42.60 481 485 488 488 488 1113 452 453 509 42.62 470 486 477 477 477 1115 465 485 517 42.64 522 491 457 457 457 1116 452 439 496 42.66 503 505 475 475 475 1089 449 481 479 42.68 553 461 502 502 502 1038 485 450 532 42.70 525 485 478 478 478 995 434 487 498 42.72 577 467 473 473 473 953 452 489 514 42.74 598 455 460 460 460 952 469 470 485 42.76 649 504 460 460 460 905 465 489 481 42.78 675 491 501 501 501 818 431 464 499 42.80 748 479 462 462 462 736 491 472 484 42.82 849 493 458 458 458 678 465 487 495 42.84 843 499 496 496 496 639 465 455 519 42.86 905 519 475 475 475 635 471 465 457 274 Gravity Gravity Blow Blow Blow Blow Aeration Aeration Aeration 26 1 2 1 2 3 4 1 2 3 42.88 917 508 477 477 477 586 474 489 485 42.90 974 525 467 467 467 555 490 481 470 42.92 996 545 464 464 464 561 447 476 546 42.94 967 592 459 459 459 506 491 472 487 42.96 993 653 485 485 485 529 475 478 517 42.98 1047 687 491 491 491 508 453 481 523 43.00 1070 738 487 487 487 529 502 482 527 43.02 1139 927 513 513 513 475 461 497 509 43.04 1227 1021 535 535 535 514 494 459 524 43.06 1299 1043 551 551 551 490 480 515 563 43.08 1294 1163 625 625 625 487 434 456 605 43.10 1313 1224 685 685 685 486 479 459 779 43.12 1281 1224 784 784 784 507 427 483 931 43.14 1325 1320 915 915 915 491 471 484 1161 43.16 1270 1331 1028 1028 1028 515 456 489 1431 43.18 1276 1377 1278 1278 1278 483 476 489 1648 43.20 1126 1411 1529 1529 1529 506 470 486 1913 43.22 1029 1441 1674 1674 1674 486 470 505 2169 43.24 917 1353 1743 1743 1743 523 481 477 2375 43.26 835 1254 1817 1817 1817 504 479 474 2392 43.28 791 1178 1889 1889 1889 513 499 454 2399 43.30 711 1135 1841 1841 1841 509 491 489 2360 43.32 631 1070 1866 1866 1866 479 492 484 2206 43.34 582 925 1669 1669 1669 491 512 501 2045 43.36 544 819 1495 1495 1495 485 525 463 1855 43.38 498 779 1237 1237 1237 511 566 490 1671 43.40 506 687 1113 1113 1113 488 507 467 1435 43.42 472 680 971 971 971 501 576 547 1253 43.44 475 611 935 935 935 486 543 525 1080 43.46 450 562 805 805 805 503 547 517 864 43.48 483 527 677 677 677 491 608 551 763 43.50 452 479 566 566 566 493 626 579 669 43.52 490 474 509 509 509 486 650 663 601 43.54 507 503 510 510 510 502 661 770 558 43.56 480 459 490 490 490 490 700 893 529 43.58 481 491 469 469 469 487 655 1075 495 43.60 457 474 459 459 459 489 655 1363 513 43.62 471 464 478 478 478 511 677 1565 465 43.64 452 485 493 493 493 513 691 1784 487 43.66 461 484 468 468 468 482 691 1942 463 43.68 432 479 467 467 467 505 649 2256 479 43.70 447 477 487 487 487 489 627 2390 487 43.72 453 464 475 475 475 479 617 2484 471 43.74 480 480 469 469 469 465 627 2556 491 43.76 471 453 484 484 484 490 600 2523 459 43.78 457 445 494 494 494 485 545 2489 494 43.80 513 453 462 462 462 510 521 2245 461 43.82 491 513 433 433 433 511 523 2054 486 275 Gravity Gravity Blow Blow Blow Blow Aeration Aeration Aeration 20 1 2 1 2 3 4 1 2 3 43.84 439 474 425 425 425 487 510 1909 461 43.86 467 432 455 455 455 458 462 1565 469 43.88 451 449 451 451 451 502 475 1356 471 43.90 465 478 431 431 431 493 487 1164 478 43.92 456 449 458 458 458 505 439 1009 450 43.94 435 471 461 461 461 483 468 825 451 43.96 429 459 440 440 440 472 439 735 457 43.98 465 457 474 474 474 483 451 607 465 44.00 458 467 458 458 458 471 451 544 455 44.02 447 454 434 434 434 522 448 529 472 44.04 477 453 444 444 444 491 458 510 479 44.06 452 445 424 424 424 480 435 477 471 44.08 447 447 428 428 428 484 445 490 505 44.10 465 458 451 451 451 461 449 492 464 44.12 485 461 451 451 451 504 449 473 451 44.14 468 475 445 445 445 453 431 457 481 44.16 446 426 475 475 475 475 439 465 493 44.18 436 447 465 465 465 475 436 443 491 44.20 491 451 459 459 459 472 449 485 455 44.22 479 421 452 452 452 468 423 495 459 44.24 459 459 427 427 427 454 433 485 486 44.26 477 438 439 439 439 500 465 507 443 44.28 439 441 451 451 451 442 468 455 412 44.30 456 447 477 477 477 485 435 437 465 44.32 431 433 465 465 465 470 461 458 439 44.34 427 427 459 459 459 477 456 483 472 44.36 445 437 446 446 446 509 457 435 471 44.38 446 476 447 447 447 492 460 480 455 44.40 477 455 461 461 461 490 441 469 480 44.42 469 454 410 410 410 478 445 474 443 44.44 451 449 435 435 435 463 445 484 450 44.46 399 441 462 462 462 457 475 477 451 44.48 451 426 456 456 456 495 466 473 472 44.50 432 433 457 457 457 473 419 497 451 44.52 469 469 469 469 469 517 445 451 428 44.54 427 439 431 431 431 512 439 448 455 44.56 431 463 464 464 464 513 431 480 477 44.58 429 448 457 457 457 489 461 471 444 44.60 415 431 489 489 489 485 463 471 449 44.62 447 449 439 439 439 486 459 476 460 44.64 447 486 437 437 437 501 442 428 467 44.66 443 451 469 469 469 490 448 443 439 44.68 461 430 432 432 432 496 445 429 438 44.70 445 443 433 433 433 508 445 452 446 44.72 448 452 436 436 436 486 424 472 454 44.74 425 415 451 451 451 471 459 462 480 44.76 437 419 447 447 447 500 448 421 482 44.78 423 453 431 431 431 520 451 469 455 276 Gravity Gravity Blow Blow Blow Blow Jderatio n >iteratio n ,deratio n 29 1 2 1 2 3 4 1 2 3 44.80 405 447 428 428 428 529 450 497 462 44.82 441 461 450 450 450 492 445 421 439 44.84 444 447 433 433 433 477 461 475 457 44.86 447 454 436 436 436 481 425 487 459 44.88 445 488 426 426 426 491 422 463 447 44.90 448 446 437 437 437 492 445 453 479 44.92 465 463 426 426 426 486 460 470 489 44.94 439 427 412 412 412 487 418 463 454 44.96 463 459 402 402 402 489 448 466 468 44.98 451 431 440 440 440 463 453 453 482 45.00 437 439 427 427 427 482 447 457 415 45.02 463 439 400 400 400 472 475 466 465 45.04 435 439 424 424 424 524 447 459 461 45.06 451 427 408 408 408 470 433 439 422 45.08 439 401 421 421 421 465 441 435 443 45.10 431 441 429 429 429 495 451 453 442 45.12 457 462 440 440 440 467 427 433 439 45.14 428 431 441 441 441 492 423 462 467 45.16 453 442 443 443 443 469 452 428 477 45.18 417 433 425 425 425 491 431 478 430 45.20 399 446 452 452 452 467 431 428 434 45.22 449 453 434 434 434 490 445 451 460 45.24 467 449 451 451 451 496 443 437 433 45.26 431 435 427 427 427 499 451 464 449 45.28 407 470 405 405 405 493 456 444 439 45.30 458 429 406 406 406 543 423 437 491 45.32 441 428 423 423 423 489 457 435 442 45.34 425 459 437 437 437 491 431 433 435 45.36 437 423 434 434 434 503 423 433 432 45.38 443 427 417 417 417 455 450 437 454 45.40 431 427 480 480 480 477 428 433 410 45.42 455 436 434 434 434 452 422 475 441 45.44 413 447 451 451 451 497 416 445 464 45.46 431 438 426 426 426 460 434 411 442 45.48 421 472 450 450 450 485 429 427 434 45.50 433 469 431 431 431 486 453 417 465 45.52 463 429 423 423 423 495 411 441 443 45.54 467 427 448 448 448 483 445 471 433 45.56 467 431 421 421 421 463 428 431 464 45.58 459 416 430 430 430 540 423 448 457 45.60 488 455 415 415 415 505 439 421 448 45.62 450 404 427 427 427 453 429 399 427 45.64 453 427 451 451 451 523 412 463 457 45.66 451 441 429 429 429 534 447 418 409 45.68 397 427 449 449 449 545 399 414 450 45.70 429 414 399 399 399 568 426 451 439 45.72 429 476 453 453 453 545 441 430 447 45.74 433 467 398 398 398 615 431 451 451 277 Gravity Gravity Blow Blow Blow Blow Aeration Aeration Aeration 29 1 2 12 3 4 12 3 45.76 449 438 456 456 456 676 412 425 455 45.78 433 431 437 437 437 705 418 429 455 45.80 475 460 436 436 436 852 425 438 475 45.82 451 476 433 433 433 1082 409 469 441 45.84 440 417 439 439 439 1250 443 439 431 45.86 437 419 428 428 428 1614 417 435 459 45.88 426 439 411 411 411 1905 429 444 450 45.90 409 448 432 432 432 2141 446 424 455 45.92 430 444 442 442 442 2409 450 437 460 45.94 414 410 410 410 410 2503 441 445 471 45.96 402 433 429 429 429 2604 449 420 422 45.98 480 417 431 431 431 2561 439 457 478 46.00 445 421 458 458 458 2443 437 439 468 46.02 457 411 437 437 437 2359 454 459 453 46.04 485 412 427 427 427 2047 446 431 437 46.06 448 431 425 425 425 1814 407 477 446 46.08 431 422 427 427 427 1643 420 444 433 46.10 452 453 395 395 395 1382 449 471 450 46.12 431 412 438 438 438 1277 457 451 458 46.14 483 451 413 413 413 1005 449 429 453 46.16 469 453 421 421 421 853 430 427 431 46.18 470 441 443 443 443 693 406 471 477 46.20 496 448 417 417 417 597 456 442 450 46.22 497 463 439 439 439 537 418 411 449 46.24 490 457 440 440 440 516 410 485 459 46.26 553 497 449 449 449 474 438 413 481 46.28 555 473 453 453 453 511 451 467 517 46.30 568 559 464 464 464 437 423 475 472 46.32 547 555 495 495 495 469 428 464 443 46.34 572 597 497 497 497 491 427 477 454 46.36 575 691 544 544 544 452 419 472 443 46.38 558 733 497 497 497 448 405 462 441 46.40 589 889 551 551 551 475 426 465 507 46.42 575 1015 599 599 599 453 438 504 517 46.44 527 1076 597 597 597 453 454 499 547 46.46 532 1069 635 635 635 414 464 482 555 46.48 521 983 633 633 633 469 445 450 599 46.50 540 1004 635 635 635 445 458 475 680 46.52 467 1017 693 693 693 472 476 462 745 46.54 499 1077 691 691 691 443 495 449 877 46.56 455 967 687 687 687 444 508 455 879 46.58 454 876 711 711 711 437 495 449 901 46.60 443 847 677 677 677 415 510 485 961 46.62 446 713 712 712 712 447 529 449 1033 46.64 427 700 700 700 700 439 517 434 957 46.66 433 629 681 681 681 459 554 446 1039 46.68 391 581 579 579 579 441 537 421 1017 46.70 453 551 587 587 587 445 555 437 941 278 Gravity Gravity Blow Blow Blow Blow deration J deration Aeration 29 1 2 1 2 3 4 1 2 3 46.72 422 535 517 517 517 466 589 445 911 46.74 424 482 537 537 537 431 579 425 778 46.76 411 453 544 544 544 449 593 455 740 46.78 425 437 487 487 487 421 622 483 696 46.80 423 421 480 480 480 417 626 503 593 46.82 411 441 497 497 497 456 636 488 615 46.84 425 452 449 449 449 417 644 509 541 46.86 403 436 443 443 443 449 627 544 523 46.88 397 435 448 448 448 432 681 547 519 46.90 379 399 425 425 425 417 619 615 433 46.92 397 413 429 429 429 480 614 625 458 46.94 419 414 439 439 439 447 554 635 443 46.96 435 433 417 417 417 451 593 737 459 46.98 405 415 401 401 401 470 569 751 453 47.00 407 391 422 422 422 412 567 791 425 47.02 413 419 413 413 413 461 539 805 449 47.04 409 413 431 431 431 448 558 819 421 47.06 445 424 423 423 423 435 503 847 470 47.08 415 441 431 431 431 429 486 822 471 47.10 405 426 431 431 431 423 432 786 492 47.12 417 416 435 435 435 425 462 749 479 47.14 375 400 424 424 424 424 425 734 499 47.16 414 419 421 421 421 437 441 683 477 47.18 410 366 427 427 427 471 419 623 540 47.20 391 427 419 419 419 434 415 617 524 47.22 424 416 424 424 424 431 447 535 576 47.24 413 393 417 417 417 423 393 548 563 47.26 395 435 424 424 424 437 413 494 583 47.28 427 415 423 423 423 455 411 491 561 47.30 393 391 427 427 427 471 392 455 609 47.32 393 431 413 413 413 445 403 478 589 47.34 403 407 441 441 441 429 403 423 581 47.36 391 410 403 403 403 426 411 452 560 47.38 391 387 411 411 411 427 401 433 538 47.40 429 427 394 394 394 435 421 403 538 47.42 400 419 391 391 391 414 426 419 533 47.44 373 392 412 412 412 449 419 414 499 47.46 407 411 421 421 421 453 403 421 501 47.48 428 416 408 408 408 428 387 403 474 47.50 415 409 399 399 399 454 425 417 458 47.52 443 427 387 387 387 430 381 403 485 47.54 387 403 420 420 420 435 373 431 458 47.56 408 415 417 417 417 462 397 417 434 47.58 391 406 411 411 411 447 371 430 449 47.60 441 414 409 409 409 433 429 427 447 47.62 396 431 379 379 379 446 409 407 473 47.64 411 450 403 403 403 480 403 435 453 47.66 374 405 383 383 383 433 400 436 424 279 Gravity Gravity Blow Blow Blow Blow Aeration Aeration Aeration 29 1 2 1 2 3 4 1 2 3 47.68 406 454 384 384 384 408 397 413 473 47.70 370 401 406 406 406 409 419 399 449 47.72 419 455 397 397 397 441 389 407 409 47.74 417 454 403 403 403 422 413 443 438 47.76 398 469 369 369 369 420 390 395 431 47.78 387 460 395 395 395 435 400 441 425 47.80 405 463 399 399 399 439 383 404 459 47.82 399 479 426 426 426 437 397 419 431 47.84 408 489 381 381 381 430 387 405 445 47.86 391 496 403 403 403 433 381 415 439 47.88 432 486 403 403 403 457 394 405 425 47.90 387 483 432 432 432 415 399 405 397 47.92 387 527 397 397 397 458 379 381 415 47.94 386 486 398 398 398 437 408 423 431 47.96 418 465 397 397 397 441 421 418 442 47.98 431 499 405 405 405 420 384 398 411 48.00 405 476 390 390 390 433 393 401 443 48.02 384 467 385 385 385 430 403 399 426 48.04 371 476 400 400 400 454 403 393 435 48.06 397 458 411 411 411 417 405 408 422 48.08 406 487 398 398 398 469 377 405 420 48.10 364 496 402 402 402 449 391 384 405 48.12 401 476 406 406 406 439 386 403 403 48.14 401 451 405 405 405 421 419 398 427 48.16 405 460 389 389 389 423 393 392 396 48.18 420 444 384 384 384 397 400 428 372 48.20 393 490 415 415 415 426 397 397 401 48.22 383 462 394 394 394 413 378 404 420 48.24 376 463 392 392 392 444 410 384 396 48.26 385 439 395 395 395 435 415 383 419 48.28 403 421 413 413 413 444 371 387 425 48.30 381 425 375 375 375 422 405 404 448 48.32 391 418 389 389 389 435 395 398 418 48.34 400 419 395 395 395 427 367 399 413 48.36 400 425 406 406 406 415 395 389 426 48.38 394 419 374 374 374 429 389 426 419 48.40 397 414 387 387 387 409 395 433 431 48.42 416 395 369 369 369 425 379 403 419 48.44 399 408 384 384 384 443 406 399 437 48.46 403 416 393 393 393 421 401 391 402 48.48 364 423 455 455 455 443 424 415 421 48.50 433 435 369 369 369 421 395 403 393 48.52 404 446 400 400 400 452 423 383 399 48.54 409 441 366 366 366 413 377 408 411 48.56 383 571 399 399 399 429 417 395 417 48.58 399 603 412 412 412 453 391 398 401 48.60 377 701 389 389 389 439 379 389 419 48.62 397 756 372 372 372 425 412 405 440 280 Gravity Gravity Blow Blow Blow Blow deration Aeration ,deratio n 29 1 2 1 2 3 4 1 2 3 48.64 399 882 374 374 374 419 401 403 411 48.66 400 864 377 377 377 422 383 410 380 48.68 416 871 361 361 361 424 405 409 414 48.70 398 898 366 366 366 427 425 401 421 48.72 416 900 381 381 381 423 411 417 422 48.74 452 866 393 393 393 433 397 421 390 48.76 428 767 387 387 387 427 404 398 415 48.78 461 768 375 375 375 427 434 405 407 48.80 437 675 401 401 401 439 414 405 394 48.82 453 616 400 400 400 400 414 393 402 48.84 455 588 403 403 403 433 383 390 398 48.86 449 549 385 385 385 444 382 395 390 48.88 468 535 397 397 397 418 392 368 392 48.90 463 467 401 401 401 448 429 391 431 48.92 425 438 378 378 378 412 385 381 405 48.94 455 457 373 373 373 413 395 375 367 48.96 432 436 383 383 383 439 377 410 414 48.98 417 435 401 401 401 411 385 369 410 49.00 410 411 371 371 371 423 373 381 385 49.02 404 414 395 395 395 439 410 367 390 49.04 417 405 382 382 382 435 358 394 400 49.06 390 383 383 383 383 431 358 378 385 49.08 401 376 378 378 378 444 395 399 401 49.10 381 389 379 379 379 435 387 408 411 49.12 403 385 377 377 377 445 393 390 425 49.14 385 390 439 439 439 447 371 402 394 49.16 409 399 387 387 387 443 399 400 388 49.18 384 406 403 403 403 418 381 381 407 49.20 389 403 373 373 373 439 407 391 380 49.22 445 392 388 388 388 426 387 389 407 49.24 383 417 395 395 395 442 401 404 417 49.26 433 381 385 385 385 441 381 379 406 49.28 415 396 355 355 355 421 399 359 392 49.30 415 405 411 411 411 431 384 397 383 49.32 378 408 379 379 379 466 389 409 397 49.34 394 397 379 379 379 439 393 436 395 49.36 392 431 391 391 391 429 420 376 423 49.38 388 434 378 378 378 455 397 401 386 49.40 387 428 393 393 393 445 400 358 417 49.42 401 397 395 395 395 411 390 383 393 49.44 377 419 379 379 379 456 400 402 386 49.46 399 435 403 403 403 425 389 388 421 49.48 390 430 391 391 391 443 397 400 410 49.50 408 485 412 412 412 441 401 405 415 49.52 423 461 357 357 357 427 388 375 408 49.54 379 487 386 386 386 448 389 387 408 49.56 419 466 385 385 385 483 385 402 409 49.58 410 496 386 386 386 416 374 416 401 281 Gravity Gravity Blow Blow Blow Blow Aeration Aeration ,Aeratio n 29 1 2 1 2 3 4 1 2 3 49.60 381 516 374 374 374 425 354 421 405 49.62 365 493 389 389 389 412 379 372 377 49.64 399 513 405 405 405 451 370 425 391 49.66 384 509 401 401 401 468 367 372 383 49.68 412 471 415 415 415 462 383 399 389 49.70 421 461 369 369 369 453 375 433 389 49.72 417 449 389 389 389 433 397 412 393 49.74 377 473 395 395 395 461 384 431 389 49.76 378 421 370 370 370 430 393 387 391 49.78 387 419 413 413 413 439 387 397 419 49.80 405 431 419 419 419 433 391 406 406 49.82 391 426 363 363 363 431 401 395 387 49.84 387 430 389 389 389 442 377 411 373 49.86 411 427 373 373 373 452 391 369 355 49.88 413 406 377 377 377 437 389 388 427 49.90 379 441 394 394 394 453 377 365 409 49.92 403 426 370 370 370 478 404 400 407 49.94 383 404 385 385 385 518 422 414 415 49.96 389 391 409 409 409 504 382 364 408 49.98 387 393 389 389 389 547 410 399 375 50.00 404 450 384 384 389 585 395 377 425 50.02 385 414 382 382 365 602 375 388 388 50.04 399 393 383 383 401 661 380 379 425 50.06 410 395 377 377 379 677 351 399 389 50.08 390 373 376 376 401 719 381 383 411 50.10 402 420 398 398 385 837 411 372 387 50.12 399 425 383 383 413 864 433 390 389 50.14 400 406 389 389 379 926 416 366 437 50.16 415 425 389 389 428 1148 394 390 379 50.18 409 443 380 380 376 1258 431 374 375 50.20 384 402 381 381 381 1473 427 415 396 50.22 426 415 395 395 375 1700 409 402 377 50.24 423 408 369 369 393 1963 450 384 400 50.26 427 436 384 384 376 2074 451 372 421 50.28 477 438 385 385 370 2288 469 391 415 50.30 412 406 387 387 373 2345 448 389 427 50.32 438 447 387 387 396 2339 443 424 397 50.34 493 455 407 407 393 2340 459 391 406 50.36 500 436 388 388 381 2413 418 373 377 50.38 507 480 421 421 384 2383 449 407 392 50.40 511 460 406 406 398 2327 445 395 406 50.42 546 467 373 373 403 2137 433 424 408 50.44 533 496 389 389 387 2001 436 401 386 50.46 616 557 397 397 417 1663 417 392 403 50.48 661 625 409 409 440 1473 413 381 396 50.50 767 787 383 383 443 1286 403 407 423 50.52 810 837 387 387 379 1173 421 415 399 50.54 935 975 419 419 399 1057 423 421 412 282 UUlUlUlUlUlUlWUlUlUlUlUlUUlUlUlUlUlUUllA oooooooooooooooooooooo o UlvlOOiOKUOiaoOOMWU^^W-O-JUiMO ^NJKJoouJOOvoooLno\ui--JOOa\ooN)-jH-a\vo HMMIOMMIONMMHHH to^ U)U)U)U)N>H-000 s -j-~joouiNJK-H-oOMU)isJK-i>jmoo--j\ooo^.ji.o 3 s to oo 2 U) ST Cd 3 \0OWtOV0U>U<©Ul\0UlV0<-*>0000t0U>O<-A--J--J00 > (0V1O^W9H000OVI0\MIOMWIOMOO-JOH o s > ft oonooo«oo*Hviaoao VO -J *- O VO •— -J © i-- > CD o 13 APPENDIX M Green Properties Test Results of Various Sands in Aeration Moisture Mold Bulk Compactibility Permeability GCS Friability Sand Content Hardness Density (%) (#) (psi) (%) (%) (#) (lbs/cu.ft) Lake 30 2 220 19 98 9.5 61.8 Lake 30 2.1 220 20.7 96 9.3 61.2 Lake 30 1.9 221 19.6 99 7.5 61.8 Lake 30 2 219 20 99 10.2 63.0 Lake 35 2.2 225 25.2 94 7 60.5 Lake 35 2.3 224 24.5 95 7.3 61.2 Lake 35 2.2 226 25.2 95 6.9 60.6 Lake 35 2.5 225 25.1 95 6.9 59.9 Lake 40 2.5 229 20.5 92 5.5 58.1 Lake 40 2.6 228 21.2 93 4.5 58.7 Lake 40 2.5 230 20.36 93 4.9 58.7 Lake 40 2.4 234 21.9 92 5.5 57.4 RG 30 2 182 22.5 98 9.5 71.8 RG 30 2.1 186 21.5 99 9.1 73.0 RG 30 1.9 185 20 96 9 69.9 RG 30 2 184 21.9 99 10.2 74.9 RG 35 2.2 193 25.3 94 7 68.7 RG 35 2.3 189 24.5 92 7.3 69.9 RG 35 2.1 190 25.2 90 7.9 70.5 RG 35 2.3 190 26.1 94 7.9 67.4 RG 40 2.4 195 23 89 6.5 64.3 RG 40 2.5 195 23.5 90 7 63.0 RG 40 2.5 193 22.7 91 6.9 63.0 RG 40 2.4 192 23.5 88 6.5 61.8 Olivine 30 2.6 76 32 99 8.818 65.6 Olivine 30 2.7 66 31.68 100 8.103 66.5 Olivine 30 2.5 68 31.45 100 9.983 66.6 Olivine 30 2.5 72 32 99 9.1 65.6 Olivine 35 2.8 83 30.5 98 7.035 61.0 Olivine 35 2.8 76 30.5 98 7.156 61.2 Olivine 35 2.8 79 31.05 97 6.944 60.0 Olivine 35 2.9 77 30.9 99 7.5 60.5 Olivine 40 3.1 89 28.78 96 6.153 56.3 284 Moisture Mold Bulk Compactibility Permeability GCS Friability Sand Content Hardness Density (%) (#) (psi) (%) (%) (#) (lbs/cu.ft) Olivine 40 3 86 29.7 97 5.675 56.9 Olivine 40 2.9 89 29.8 96 5.28 57.4 Olivine 40 2.9 85 28.9 95 6 56.8 Chrom te 30 2 346 32.05 98 10.04 94.8 Chromi te 30 2.1 352 33.98 97 10.16 91.7 Chromi te 30 2 361 33.9 97 9.59 89.3 Chromi te 30 2.1 358 32.5 98 8.9 93.6 Chromi te 35 2.2 370 31.5 95 8.62 82.0 Chromi te 35 2.3 369 31.05 95 7.09 82.8 Chromi te 35 2.3 372 30.61 95 7.39 81.1 Chromi te 35 2.2 369 30.2 96 8.5 82.1 Chromi te 40 2.5 378 25.09 94 5.74 79.0 Chromi te 40 2.4 391 24.59 95 5.52 78.6 Chromi te 40 2.4 381 28.83 94 4.12 78.1 Chromite 40 2.3 385 26.7 94 5.8 77.4 Ceramic Media 30 2.35 226 32.46 97 10.01 76.1 Ceramic Media 30 2.3 226 32.5 97 10.07 76.0 Ceramic Media 30 2.3 224 31.2 98 9.51 74.0 Ceramic Media 30 2.4 231 32.22 98 9.48 72.2 Ceramic Media 35 2.4 237 30.6 95 7.9 69.3 Ceramic Media 35 2.5 238 31.5 95 7.38 68.8 Ceramic Media 35 2.55 236 29.99 95.5 8.2 68.3 Ceramic Media 35 2.45 238 30.1 95 7.5 69.3 Ceramic Media 40 2.7 241 29.75 94.5 6.92 64.4 Ceramic Media 40 2.7 254 29.5 94 6.12 64.8 Ceramic Media 40 2.7 249 28.5 94 6.55 64.5 Ceramic'.vledi a 40 2.6 250 28.3 95 6.15 64.9 285 Appendix N Green Properties of Lake Silica Sand for Validation Bulk Mold Compactibility Density Permeability GCS Hardenss Friability Technique N (%) (Ibs/cu.ft) (#) (psi) (#) (%) 1 35 58 233 23.5 95 18 2 36 58.3 230 24 96 17 3 36 53 235 24.2 94 18 4 34 53.5 233 23.9 93 15 5 34 58 227 24.5 94 16 6 35 59.6 229 25 94 17.3 7 35 235 24.6 94 17.5 As Mulled 60.5 8 36 58 237 23.1 94 17.2 9 35 85.9 233 23 93 16.5 10 34 58 231 24.5 94 16.2 11 36 60 238 24 94 16 12 35 55.2 235 24.1 94 15.2 Averaqe 35.08 59.83 233 24.03 94.08 16.66 Std 0.79 8.55 3.28 0.6 0.79 1 1 35 62 220 23.6 93 6.5 2 36 62 225 23.5 94 6.8 3 36 63.5 225 24.2 94 7 4 34 65.1 223 24.5 94 7.2 5 34 62.5 223 25 95 7.5 6 35 63.5 221 21.5 95 6.5 7 35 64.2 227 23.5 94 6.8 8 36 64 218 24.2 94 6.9 9 35 64 223 24 94 7.5 10 34 65.5 224 24.1 94 7 11 36 65.3 223 24.2 93 7.2 12 35 65.6 223 24.2 94 7 222.92 23.88 94 6.99 Aeration Averaqe 35.08 63.93 Std 0.79 1.29 2.39 0.86 0.6 0.33 286 Appendix O Results of the Test Casting: Erosion Depth Erosion No. Techniques Squeeze Pressure Head Height (mm) Depth 1 Aeration High 75 0.1 2 Aeration High 150 0.12 3 Aeration Low 75 0.32 4 Aeration Low 150 0.8 5 Aeration High 75 0.08 6 Aeration High 150 0.14 7 Aeration Low 75 0.36 8 Aeration Low 150 0.85 9 Aeration High 75 0.08 10 Aeration High 150 0.14 11 Aeration Low 75 0.4 12 Aeration Low 150 0.8 13 Aeration High 75 0.08 14 Aeration High 150 0.12 15 Aeration Low 75 0.42 16 Aeration Low 150 0.9 17 Gravity High 75 0.2 18 Gravity High 150 0.36 19 Gravity Low 75 1.6 20 Gravity Low 150 2.5 21 Gravity High 75 0.18 22 Gravity High 150 0.32 23 Gravity Low 75 1.5 24 Gravity Low 150 2.4 25 Gravity High 75 0.22 26 Gravity High 150 0.3 27 Gravity Low 75 1.4 28 Gravity Low 150 2.6 29 Gravity High 75 0.2 30 Gravity High 150 0.32 31 Gravity Low 75 1.6 32 Gravity Low 150 2.8 287