Instructions for Authors s4

Proceedings in MANUFACTURING SYSTEMS Proceedings in Manufacturing Systems, Vol. 5 (2010), No.

SURFACE QUALITY ANALYSIS OF 102Cr6 BEARING STEEL AFTER CC6050 INSERT BY HARD TURNING AND BY SG GRINDING WHEEL

Jana ŠTEININGEROVÁ1, Jozef MAJERÍK2

Abstract: This paper is specialized about qualitative aspects analysis of machined surface by hard turning with CC6050 cutting ceramics cutting tool and by progressive grinding with SG grinding wheel on the Seeded Gel grain application. The main area of this article discuss about analysis of cutting condition influence and also other parameters which relates with surface roughness and Abbott surface profile and microstructure. Applied cutting conditions (parameters) expected fatigue strength affection or wearing resistance etc. It is possible to appreciate the complex surface topography evaluation in term of various possible aspects. The main problem of surface integrity is a possibility to new theories creation in term of new trends of machining technology. It is necessary to advance functionality of part surfaces.

Key words: Surface Quality, Hard Turning, Progressive Grinding, Cutting Ceramics CC6050, SG (“seeded gel”)Grinding Grain, Surface Roughness.

manufacturing operations of the technological process. In 1. INTRODUCTION1 order to successfully address the quality indicators and Patterns of the cutting process and create the desired funkčnosti surfaces must be sufficient to know and be shape and size of the piece are the very essence able practically to apply the patterns of surface integrity. machining process. They are stronger and toughner new The results of recent experiments, several authors have materials, expanding the number of components focused on the study of vibration during grinding. Some requiring high quality surface. It is very hard to be vibration analysis, however, were only focused on machined and hard machined materials require high conventional abrasive, by analyzing the components of dimensional and shape accuracy and surface quality. cutting force, acceleration of the system, as well as the Parts with better surface quality bear dynamic loads, associated quality of machined surfaces. It was analyzed resist wear, resist corrosion, increasing the functional the impact of these cutting conditions, workpiece and capacity, reliability and durability of complex machine tool vibration and the quality of the cut surfaces. mechanisms, and thus also the economic advantage of In this article we focus on the issue of SG vibration in whole plant and equipment. Prerequisite to achieve high grinding wheels. Therefore, the purpose of the study is to quality components is the use of hard machining methods study oscillations in advanced applications based on (turning), and finishing by fine machining (grinding). cutting tools SG grain and its effect on surface quality. It The values of the surface quality of machine parts is to is also considered the issue of hard turning with RK (Fig be found in its own production technology, especially in 4). These indicators are a prerequisite for the effect of the cutting operation. [6]. The task of examining the fatigue strength, wear resistance, quality, fit, corrosion integrity of the surface to create new theories in light of stability etc., which is crucial especially in dynamically current trends in technological practice. Therefore, the stressed parts of machinery and equipment subject to practical conditions of the manufacturing process can be wear. deduced the following argument: The integrity of the surface has a significant impact sequence of 2. METHODOLOGY OF EXPERIMENTS

11, Dubnica Institute of Technology in Dubnica nad Vahom, The experiments were used bearing steel 102Cr6, Specialistic subjects, University teacher, Sladkovicova 533/20, 01841 Dubnica nad Vahom, Slovakia, Tel./Fax,: +421918595640, hardened to 62 HRC. Its chemical composition is shown E-mail: [email protected] in Tab.1 and a microstructure, which consists of 2, Dubnica Institute of Technology in Dubnica nad Vahom, martensite (Fig.1). Chemical composition and Specialistic subjects, University teacher, Sladkovicova 533/20, mechanical properties were measured on a spectrum 01841 Dubnica nad Vahom, Slovakia, Tel./Fax,: +421907409452, E-mail: [email protected] analyzer JrCCD Spectrolab. Quantities of a single elements cultivated in steel in Table 1 Measured results allow verification of compliance with standards in the manufacture and heat treatment of steel. 4 0,04 8 2 520 195 Table 1 When comparing the SG grinding wheels are applied to the following cutting conditions: inside corner to cut ap Chemical composition of bearing steel 102Cr6 (mm) desk displacement vf (m.min-1) speed n (min-1) in Figure 2. Cutting fluids used in grinding - EMULZÍN H (2% concentration), flow rate 8 l / min, dressing rolls Chemical ( % ) (Al2O3, SG) – single-piece diamond dressing, ap = 0.02 Composi- mm, fd = 80 μm. In hard turning test samples of CA- tion C Mn Si Cr Cu Ni P S ceramics (CC6050) were used for the following cutting -1 1,30 parameters: n = 1600 min ap = 0,2 mm ≤ ≤ ≤ ≤ ≤ max. max. -1 102Cr6 až 1,1 1,2 0,65 0,25 0,3 0,027 0,03 f = 0,141 mm vc = 142,7 m.min 1,65

Fig. 3. Microstructure of surface layers of steel 102Cr6 after hard turning dry etched Nital 3% 500x magnification [2]

Fig. 1. Device for measuring the spectral analysis JrCCD [5] In Fig. 2 and 3 to see the microstructure of steel 102Cr6. The surface area of hard turning is present continuous layer of residual austenite on the thickness of max. 2 mm, see below annealed globular martensite and carbides. The surface layer after grinding were observed incidence of residual austenite layer, the structure is well formed martensite and annealed fine globular carbides. In the experiments for the analysis of cutting forces in terms of static and dynamic evaluation and follow mikrogeometrie surface [2].

2.1. Used for cutting hard material turning - ceramic cutting insert CC6050

Fig. 2. Microstructure of surface layers of steel 102Cr6 after There are many uses of ceramic materials, due to grinding, etched Nital 3% magnification 500x [2] higher hardness and wear resistance, and is the result of strong ionic or covalent bond. The growing field of application of ceramic materials in machining, where Table cutting operations are increasingly replacing traditional 2 methods of grinding. Designers constantly require new materials with increased strength, hardness, thermal Grinding cutting conditions properties and wear resistance. But the same characteristics, making the appropriate these materials, Grinding they do a hard cultivable. Two examples are hardened Measurement ap vf n wheel steel and alloys, which are holders of strength and wear number [mm] [m.min-1) [min-1) diameter [mm) resistance in many applications that retain strength at high temperatures of operation. Because these materials 1 0,01 8 2 520 195 are often used in applications where the degree of precision is required that at least one of machining 2 0,02 8 2 520 195 processes, technology applied in practice required to cast 3 0,03 8 2 520 195 or forged, made adequate dimensional precision surface F1. Surname1 et al. / Proceedings in Manufacturing Systems, Vol. 5 (2010), No. 1 / 110 (8 pt, Italic) 3 quality. As an example of a typical application uses a Components of shear strength of worn wheels Al2O3, SG hardened steel bearing mention manufacture for the after withdrawal Vw '= 1500 mm3.mm-1 are shown in automotive industry. (Fig.5 and Fig 7). Ceramic cutting materials are characterized by high hardness, which is preserved even at high operating temperatures of 1000 ÷ 1300 ° C. They are chemically stable and in the cutting process do not react with the workpiece material. Durability of cutting edge ceramic plates aside under the right conditions is very good. Ceramic cutting tools from ceramics (CC "Coromant) make large amount of material removed using high cutting speeds [2]. To achieve the quality of the machining process is needed to match the parameters of cutting ceramics that we have available cutting plate with the required physico-mechanical and chemical properties. Among the characteristics influencing the use of CC during operation include hardness, tensile strength and bending strength, structure and thermal properties. Very effective Fig. 5. Record the signal components of cutting force Fc and is a homogeneous fine-grain structure of CC, as has a 3 -1 Fp for vw '= mm .mm in a grinding Al2O3 at ap = 0.03 mm, very good strength characteristics required for machining wheel diameter 195 mm [1] of high materials. Strength estate in pressure is comparable with the strength of SK. However, the bending strength is lower compared with carbides. Therefore, the choice of CA must choose the correct geometry of the cutting plate so that the process of cutting the rigid ceramic plate mainly the least pressure and bending forces (negative angles γ and λ, negative collar at the forefront of cutting edge).

Fig. 6. Record the signal components of cutting force Fc and 3 -1 Fp for Vw '= 1500 mm .mm grinding in an Al2O3 at ap = 0, 03 mm, wheel diameter 195 mm [1]

Fig. 4. Hard turning of the test sample of an instrument with CA-estate CC6050 on CNC lathe HARRISON Alpha 1300S

3. EXPERIMENTAL RESULTS

3.1. Analysis of the relationship between the

components of cutting force and the amount of Fig. 7. Record the signal components of cutting force Fc and 3 -1 material removed during grinding Fp for Vw '= 1500 mm .mm in grinding SG at ap = 0.03 mm, wheel diameter 195 mm [1] Cutting force components were recorded in the computer under the scheme of experimental Furthermore, the records are filtered components of measurements. Records thus obtained were analyzed and cutting force on the static and dynamic component of consisted of a static view (Fig 8) as well as dynamic cutting forces are operating affect the grinding wheel components of cutting force (Fig 9). In (Fig 5 and Fig 7) wear on the size of the static cutting force components are characteristic components of cutting force records for different depth of cut. In particular, the RMS value of compared grinding wheels. Recording (Fig.5) shows the cutting force components are much smaller (less dynamic components of cutting force after the withdrawal Vw '= activity) in the applications of this type of abrasive and 3 -1 30 mm .mm , an Al2O3 plate after alignment. grinding wheel to maintain a stable long-term significance of change without cutting action force. These phenomena also verify the measurements of other 3.2. Analysis of the impact grinded volume of authors who have dealt with this issue in the past and material to the surface roughness show that the inside corner to the upper section, which ensures samoostrenie abrasive cloths size measurement Another area analyzed the impact of dynamic cutting 2-3 times greater in the application of SG grain compared process and the shape of the abrasive surface roughness with conventional abrasives [ 3], [4]. [1]. Roughness of the surface components were evaluated for selected numbers of wheel passes in five

160 places, which were subsequently calculated aritmetic average. Entries were evaluated in an Dasylab 4.0. Thus, 140 the records were analyzed for various parameters and

120 surface roughness Ra, RQ, Rz. In (Fig 10 and Fig 12) are 100 characterized by the records of surface roughness after ]

N grinding has compared grinding wheels and Al2O3, SG. [

F Record of surface roughness on (Fig 10) is the 60 3 -1 removal Vw '= 30 mm .mm - wheel Al2O3 after facing. SG 40 Records of surface roughness Al2O3 discs, SG after the 3 -1 20 Al2O3 withdrawal of material Vw '= 1180 mm .mm are shown in (Fig 11 and Fig 12). Comparing (Fig 10 and Fig 11) it 0 is seen that the surface roughness with ap = 0.03 mm in 0 250 500 750 1000 1250 1500 the V ' changes, which is caused by the grinding wheel V ' [mm3.mm-1] w w 3 -1 wear. VW '= 1180 mm .mm in Fig 11 to Fig 12 shows that the amount microinequality surfaces were polished Fig. 8. Effect Vw ' the size of the static component of force Fp at

ap = 0.03 mm [1] wheels SG is significantly lower than in Al2O3 surfaces polished blade, which is related to wear and shape, Measurement of the static cutting force components abrasive at higher inside corner to cut. showed that differences between the grinding wheels, 10 etc. are all relatively small especially for small values 8 ]

m 6 µ and so forth. Also, that at higher ap values are static Fp [

i 4 t s

Al2O3 for less than the application of SG disc (Fig 8), o 2 n

v 0 o again in conjunction with a different mechanism of r

e -2 n

abrasive wear. Analysis of the RMS values of the a -4 k

š -6 3.2. Soft copy ý components has confirmed the fact of previous studies v Use-8 the surname of first author to identify your soft- [3], [4], that in the working area of the grinding disc -10 (area where the abrasive grain usually gradually wears) copy followed1 2 by the3 numbers4 015 or 026 in case7 of two8 dĺžka [mm] the size of the RMS values of components of cutting papers with the same first author, e.g. surname_01.doc. ’ 3 -1 force significantly changed (only slightly higher values). Fig. 10. Record of surface roughness for Vw = 30 mm .mm , In the area where the grinding wheel becomes apathetic, wheel Al2O3 (D=195mm), at ap = 0,03 mm [1] their size is growing rapidly (unlike the static 10 components) and the grinding wheel should be faced. 8 ]

The results of changes in particular RMS values indicate µ

i 4 t that the differences in RMS can be seen in relation to s 2 o n long-term interaction with the piece instrument which is v 0 o r

e -2 n indicated by the effect of tool wear and is not usually

a -4 k

immediately after facing grinding wheel. ý v -8 80 -10 Al2O3 0 1 2 3 4 5 6 7 70 dĺžka [mm] SG ’ 3 -1 60 Fig. 11. Record of surface roughness for Vw =1180 mm .mm ,

wheel Al2O3 (D=195mm), at ap = 0,03 mm [1] ] 50 N [

p 10 F 40 8 S ] m

M 6 µ

30 [ R

i 4 t s 2 o

20 n v 0 o r

e -2 n

10 a -4 k

š -6 ý 0 v -8 -10 0 250 500 750 1000 1250 1500 0 1 2 3 4 5 6 7 ' 3 -1 Vw [mm .mm ] dĺžka [mm]

’ 3 -1 Fig. 12. Record of surface roughness for Vw = 1180 mm .mm , Fig. 9. Vw' the size of RMS Fp values at ap = 0,03 mm [1] wheel SG (D=195mm), at ap = 0,03 mm [1] F1. Surname1 et al. / Proceedings in Manufacturing Systems, Vol. 5 (2010), No. 1 / 110 (8 pt, Italic) 5 The small inside corner to cut the character of wear of Comparing (Fig 10 and Fig 12) shows that the grinding wheels and therefore a similar surface surface roughness at ap = 0.03 mm in the Vw' changes roughness is comparable (Fig 13 and Fig 14). which are caused by the grinding wheel wear. 16 3 -1 For Vw '= 1180 mm .mm (Fig 10 and Fig 12) shows that the amount mikronerovností surfaces were polished 14 wheels SG is significantly lower than the cut surfaces of 12 the blade in Al2O3, which is related to wear and shape, ] 10 the abrasive upper inside corner to cut. m µ

2,0 z R 6 Al2O3 Al2O3 4 1,6 2 SG SG 0 1,2 0 250 500 750 1000 1250 1500 ] 3 -1 m V ' [m m .m m ]

µ w [

a ´ R 0,8 Fig. 15. Vw influence on surface roughness Rz at ap = 0,03 mm

The upper inside corner to cut the size of Ra, RQ, Rz 0,4 SG blades for less than it shows pictures. In the context of increasing RMS values of cutting force components as well as the size increases with Ra conventional disc much 0,0 faster than in the case of grain SG [1]. In this area starts 0 250 500 750 1000 1250 1500 grinding wheel wear more and more radius abrasive V ' [m m 3.m m -1] w grains, a grain abrasives, which are beginning to create flat pads and not the cause vibration, but also a larger ´ Fig. 13. Vw ifluence on surface roughness Ra at ap = 0,03 mm, increase in the roughness of cut surface. increase in without sparks surface roughness in this area also relates to different material removal processes (deformation) in the contact Figures 13 and 14 traces of the rms. tool and workpiece. The increase in Ra values as well as some other parameters correlated with the increase in RMS values of cutting force components and is therefore heavily influenced by the cutting process dynamics.

3.3. Analysis of the effects of hard turning surface roughness Roughness of the machining conditions for each varies greatly. Its properties are largely dependent on how machining cutting conditions and geometry of the cutting tool. Existing differences in quantitative and qualitative characteristics of surface roughness machined by turning and grinding are based on different kinematic principles, different types of cutting tools as well as the different layout tool against the workpiece. The machined surfaces microgeometry single blade cutting tool is influenced by several factors. These are ´ Fig. 14. Vw influence onsurface roughness Rq at ap = 0,03 mm the effect of cutting parameters (cutting speed, feed, depth of cut), the impact on the geometry of the cutting Grinding wheels SG will maintain its long cutting knife (front angle, back angle, radius tip), the influence inside corner to the upper section with respect to their of material cutting tool (UF-EN, CC, CBN) impact ability samoostriacou which is then reflected positively vibration technological system, not least the impact of in the surface roughness (Fig 13 and Fig 14) cutting tool design. An analysis of the impact of volume grinded material Cutting parameters for hard turning were chosen to surface roughness shows that a higher portion of the achieved dimensional accuracy and surface roughness inside corner with increasing Vw 'grows and roughness. was approximately the same (Ra ≤ 0.4 μm). In (Fig 13 and Fig 15) can be seen during the various The number of standard parameters were chosen to parameters of roughness, depending on the material describe mikrogeometrie parameters that are most used impact odbrúseného Vw 'grinding wheels each (Al2O3, in practice and only 90% of producers used to express SG). In (Fig 13 and Fig 15) is a graph of "Ra, RQ, Rz“. the value of the roughness Ra and the quality of processed surface. Fig. 16. Graphic recording of a surface roughness measurement The aim was elimimating impact of different surface 102Cr6 turning dry (left) and cut (right). roughness in tribological tests, in which radial wear is higher for surfaces with greater surface roughness .Verification impact displacement (f) and cutting speed 9. CONCLUSIONS (vc) in hard turning is achieved at f = 0.1 mm surface He assessed the state of the surface layer of roughness toto Ra = 0.20 mm. It was reduced to feed f = specimens 102Cr6 hardened steel (HRC = 60 ± 2) -1 0.15 mm and rε = 0.8 mm, vc = 150 m.min , p = 0.2 mm measurement microgeometry (surface roughness and was achieved Ra = 0.33 ÷ 0.38 mm. Abbott curve), and microhardness during hardening and Test results of various machining hardened steels metallographic evaluation of the structure of surface confirm that the surface roughness in hard turning is layers and so. white layer. equal to or better than the grinding round of sparks. (Fig The microstructure of individual samples from all the 16) Turning to the use of cooling in many cases even hardened material to see a continuous white surface layer improves the surface roughness. thickness from 0.002 to 0.004 μm for all the hard turning In addition to the arithmetic average roughness Ra is of hardened steels. This white layer is absent or very thin the difference for a better assessment of the surface and interrupted during grinding. measured and assessed the proportion of material profile The results of extensive testing on the next types of (Abbott curve), as the nature of surface roughness is only high strength steels follows: slightly indicative of functional properties of the surface. - Microgeometry turned hard, dry surfaces or cooling is equal to or better than the plunge grinding, - Curve of surface roughness and material share at 40% distance from the surface of inequalities is better to cut surfaces and a 58 ÷ 60 ÷ 38% versus 40% for turning; Scientific contribution of assignments is that it broadens the knowledge of hard turning dry cooling is a wider range of machining of hardened steel, but mostly extends knowledge of the integrity of the machined surfaces and hardened steel used in automotive industry [6]. This opens the way for further research in this field, which to optimize machining processes of hardened components in the manufacture of their dominant function surfaces. It can reasonably be assumed that the development of methods and means of direct monitoring, and modeling of functional surfaces in hardened steel, will further increase the operational reliability and durability of machine parts and equipment. To further research is necessary to monitor and change the character and bearing machined surfaces and curves and verify the impact of turning CBN the integrity of the surface of hardened steel.

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