The Effects of Feedrate and Material Hardness on Burr Formation in Grinding Processes By Michelle Ladouceur Erin McLean and Liza Tuttle A Major Qualifying Project Submitted to the Faculty of the WORCESTER POLYTECHNIC INSTITUTE in partial fulfillment of the requirements for the Degree of Bachelors of Science In Mechanical Engineering April 2008 APPROVED: Prof. Christopher A. Brown, Project Advisor 1 | P a g e Table of Contents List of Tables: ................................................................................................................................. 3 List of Figures: ................................................................................................................................ 4 Abstract ........................................................................................................................................... 5 1.0 Introduction ............................................................................................................................... 6 1.1 Objectives .................................................................................................................................. 6 1.2 Rationale ................................................................................................................................... 6 1.3 State-of-the-art .......................................................................................................................... 7 1.4 Approach ................................................................................................................................. 10 2.0 Methods................................................................................................................................... 11 2.1 Create Burrs............................................................................................................................ 11 2.1.1 Preparing the Workpieces.................................................................................................... 12 2.1.2 Grinding Process ................................................................................................................. 14 2.2 Record Burrs ........................................................................................................................... 15 2.3 Measure and Analyze Burrs .................................................................................................... 16 3.0 Results ..................................................................................................................................... 18 4.0 Discussion ............................................................................................................................... 24 5.0 Conclusions ............................................................................................................................. 25 6.0 Design of a Coolant Supply System ....................................................................................... 26 References ..................................................................................................................................... 41 Appendix A: .................................................................................................................................. 43 Problems that occurred during project......................................................................................... 43 Appendix B: .................................................................................................................................. 46 Research Obsticles ........................................................................................................................ 46 Appendix C: .................................................................................................................................. 47 Operator Issues for Hardness Testing .......................................................................................... 47 Appendix D: .................................................................................................................................. 48 Properties of 440 C steel............................................................................................................... 48 Appendix E: .................................................................................................................................. 49 Macro Pictures.............................................................................................................................. 49 Appendix F: .................................................................................................................................. 55 Macro Graphs of Burrs with and without scales .......................................................................... 55 2 | P a g e List of Tables: Table 1: Hardness tests 1-4, average hardness values, and time spent in heat treatment for each workpiece ...................................................................................................................................... 13 Table 2: Workpiece Feedrate and Hardness and Measured Burr Dimensions ............................. 17 Table 3: Mean Length, Height, and Thickness for each Hardness Range .................................... 20 Table 4: Mean Length, Height, and Thickness for each Feedrate ................................................ 22 3 | P a g e List of Figures: Figure 1 : Measure HRC values for each workpiece .................................................................... 13 Figure 2 : Duration of Workpieces in Heat Treating oven compared to average HRC values…..14 Figure 3 : Burr Measurements ...................................................................................................... 16 Figure 4 : Length, Height, and Thickness of each burr vs the workpieces‟ HRC ........................ 17 Figure 5 : Workpiece Hardness vs. Burr Length ......................................................................... 18 Figure 6 : Workpiece Hardness vs. Burr Thickness .................................................................... 19 Figure 7 : Burr Length vs. Workpiece Hardness ......................................................................... 19 Figure 8 : Mean Burr Length, Height, and Thickness vs. Hardness ranges ................................ 20 Figure 9 : Burr Length compared to the Feedrate used to create it ............................................... 21 Figure 10 : Burr Height compared to the Feedrate used to create it ............................................. 21 Figure 11 : Burr Thickness compared to the Feedrate used to create it ........................................ 22 Figure 12 : Mean Burr Length, Height, and Thickness compared to Feedrate ............................. 23 Figure 13: The Temperature of the material vs. the distance from the heat source (Snoeys et al. 1973) ............................................................................................................................................. 27 Figure 14 : Fluid flow through the Hahn grinder .......................................................................... 29 Figure 15 : Function requirements ................................................................................................ 30 Figure 16 : Design Parameters ...................................................................................................... 30 Figure 17 : Dimensions and velocity diagram of a centrifugal pump (Munson, 2006) ................ 34 Figure 18 : Vector composition of V2 .......................................................................................... 34 Figure 19 : Selected pump dimensions and speed ........................................................................ 35 Figure 20 : Front view of proposed collection/holding tank......................................................... 36 Figure 21 : Top and side views of collection/holding tank ........................................................... 37 Figure 22 : Fluid transportation path (side view).......................................................................... 37 Figure 23 : Position of exit points for fluid (top view) ................................................................. 38 Figure 24 : Positions of exit pipes................................................................................................. 38 Figure 25 : Nozzle dimensions ..................................................................................................... 40 4 | P a g e Abstract This work investigates the effects of material hardness and feedrate on burr dimensions created in grinding processes. Once burr have been formed, macrographs are taken and burr length, height, and thickness is recorded. Correlations between material hardness and feedrate were not consistent from one burr dimension to the next. The unhardened workpieces produced the smallest burrs and the next smallest were found on workpieces in the 57-59 Rockwell C hardness scale. There is evidence of the material having an ideal hardness value for producing minimum and maximum burr size. 5 | P a g e 1.0 Introduction 1.1 Objectives The main objective of this project is to determine the effects of two independent variables, hardness and feedrate, on burr creation on parts of 440C stainless steel. In order to complete this objective we needed to devise methods for repeatedly creating the burrs on specialized grinding apparatus, develop a procedure for modifying