Surface finish of the bulk metallic glass using abrasive jet polishing process on the machining center

M9803807 Surface finish of the bulk metallic glass using abrasive jet polishing process on the machining center Nguyen Hai Dang Abstract This thesis aims to investigate the optimal abrasive jet polishing parameters for Zrbased bulk metallic glass (BMG) material by using the Taguchi method An abrasive jet polishing (AJP) system has been newly designed and installed on a machining center In order to determine the optimal polishing parameters for the BMG sample, four polishing parameters, namely the hydraulic pressure, the impact angle, the stand-off distance, and the polishing time were chosen as the factors of experiments The optimal AJP parameters have been determined after carrying out the experiments based on the Taguchi’s L9 orthogonal array experimental results These optimal parameters are the combination of the hydraulic pressure of kg/cm2, the impact angle of 50o, the stand-off distance of 15 mm, and the polishing time of 60 minutes The surface roughness can be improved from about Ra 0.13 m to 0.044 m by using the AJP optimal parameters Besides, an analysis of variation (ANOVA) of the experimental data indicated that the polishing time and hydraulic pressure was the dominant parameters of the AJP process for the BMG material Keywords: Abrasive jet polishing, bulk metallic glass, Taguchi method, orthogonal array, ANOVA i Acknowledgements First and foremost I would like to show my gratitude to my advisor, Professor FangJung Shiou, Director of Opto-Mechatronics Technology Center, National Taiwan University of Science and Technology, who has supported me throughout my thesis Without his patience, encouragement, guidance and immense knowledge this thesis would not have been possible Besides my advisor, I would like to thank the rest of my thesis committee: Professor Geo-Ry Tang, and Doctor Wei-Yao Hsu for the valuable comments Furthermore, my sincere thanks are due to Mr Arif, who guided me in operating the CNC machining center, Vincent, who had made his support in a number of ways and Mr Son, Mr Loc, who helped me in all the time of research and writing of this thesis Their assistance and guidance have been of great value in this study In my daily work, I am indebted to many of my other lab mates to provide me a happy and peaceful environment I would also like to thank the Library staffs who helped me in gathering a lot of information for this project I am also very appreciative of the Taiwan Government for providing me the financial support I offer my regards to all of those who supported me in any respect during my studying time Lastly and most importantly, I owe my deepest gratitude to my family for everything they have done for me Without their love, this thesis would not be finished Taiwan July 2011 ii Table of Contents Abstract i Acknowledgements ii Table of Contents iii List of Figures vi List of Tables ix Chapter INTRODUCTION 10 1.1 Research motivation 10 1.2 Literature review 10 1.2.1 BMG properties and machining ability of BMGs 10 1.2.2 Ball burnishing process 11 1.2.3 Abrasive jet polishing (AJP) process 13 1.3 Thesis objectives 14 1.4 Outline of thesis 15 Chapter BACKGROUND INFORMATION 16 2.1 Milling process and milling parameters 16 2.1.1 Milling process 16 2.1.2 Milling parameters 18 2.2 Ball burnishing process 19 2.2.1 The simplified theory of ball burnishing deformation 20 2.2.2 Effect of burnishing force on surface roughness 22 2.2.3 Effect of feed on surface roughness 23 2.2.4 Effect of ball material on surface roughness 23 2.2.5 Effect of burnishing speed on surface roughness 24 iii 2.3 AJP process 24 2.3.1 AJP system 26 2.3.2 Model for the ductile and brittle mode material removal 28 2.3.3 Parameters of the AJP process 30 2.3.4 Footprint on the workpiece after AJP process 33 2.4 Surface roughness measurement 34 Chapter TAGUCHI METHOD AND ANOVA ANALYSIS 38 3.1 Introduction 38 3.2 Control factors and noise factors 39 3.3 Orthogonal array 39 3.4 ANOVA and S/N Analysis 40 Chapter EXPERIMENTAL WORK 43 4.1 Introduction 43 4.2 BMG sample 44 4.3 Sample preparation 44 4.3.1 Milling process 44 4.3.2 Ball burnishing process 46 4.4 AJP process 50 4.4.1 System setup 50 4.4.2 Procedure to conduct the experiments 58 Chapter EXPRIMENTAL RESULT AND DISCUSSION 66 5.1 Experimental result and analysis 66 5.2 Discussion 69 Chapter CONCLUSION AND RECOMMENDATION 73 iv 6.1 Conclusion 73 6.2 Recommendation for future work 73 Appendix A 77 Appendix B 79 Appendix C 80 Appendix D 81 v List of Figures Figure 2.1 (a) Schematic drawing of the milling process (b) A 3-axis milling machine 16 Figure 2.2 The classification of milling process (a) Peripheral milling (b) Face milling (c) End milling 17 Figure 2.3 (a) Up milling (conventional milling) (b) Down milling (climb milling) 18 Figure 2.4 The illustration of axial and radial d.o.c 19 Figure 2.5 The illustration of terminologies in the ball burnishing process 20 Figure 2.6 The illustration drawing of the deformation zone in the ball burnishing method 21 Figure 2.7 The relationship between surface roughness and normal burnishing force 22 Figure 2.8 The relation between feed and height of irregularities 23 Figure 2.9 The relationship between the burnishing speed and surface roughness 24 Figure 2.10 The collision between abrasive liquid slurry jet and the workpiece surface with terminologies of impact angle , nozzle diameter d, stand-off distance s 26 Figure 2.11 The schematic drawing of AJP setup 27 Figure 2.12 (a) The premixing pumping system and (b) separate pumping system 27 Figure 2.13 The model of brittle material removal mode according to Lawn in eight steps (a), (b), (c), (d), (e), (f), (g), (h) 29 Figure 2.14 The model of ductile material removal mode in four steps (a), (b), (c), (d) 30 Figure 2.15 Schematic illustration of abrasive fluid jet in AJP 31 Figure 2.16 The footprints of a spot after AJP process under varies of impact angles (a) 90o (b) 60o (c) 45o (d) 30o 33 Figure 2.17 The footprints in case of (a) fixed nozzle (b)(c) moving along x and y axis nozzle and (d) rotating nozzle 34 Figure 2.18 The illustration of surface texture main components 35 vi Figure 2.19 The illustration of Ra and Rq 36 Figure 2.20 The illustration of Rmax and Rt 37 Figure 2.21 The illustration of Rz 37 Figure 3.1 The steps of Taguchi method to find the optimal parameters 38 Figure 3.2 The illustration of control and noise factors 39 Figure 4.1 The schedule of experimental work 43 Figure 4.2 The BMG sample 44 Figure 4.3 The milling path is generated by the Pro/Engineer software 46 Figure 4.4 The milling process of BMG sample in the machining center 46 Figure 4.5 The innovation ball burnishing tool embedded with a load cell 47 Figure 4.6 The ball burnishing process of BMG sample in machine center 48 Figure 4.7 The drawing of ball burnishing mechanism for BMG material (a) The debris are separated from the crack area, (b) the rubbing lines and fracture zones are created along the burnishing direction 49 Figure 4.8 The image of practical rubbing line and fracture zone in burnishing BMG material observed with 100x optical microscope 50 Figure 4.9 The completed AJP system is installed in the machine center 51 Figure 4.10 The tank and stirring device in (a) rest state (b) in process 52 Figure 4.11 The inverter control pump 53 Figure 4.12 The AJP tool head 54 Figure 4.13 The container with some of outlets The arrows show the direction of the slurry flow which comes back to the tank 55 Figure 4.14 The slurry was inside the tank (a) without mixed hydraulic oil and (b) with mixed hydraulic oil after hours of the AJP process 56 vii Table 5.2 The average S/N ratio by factor levels (dB) Factor Level A B C D 21.92 20.17 19.67 18.54 20.88 19.48 20.61 22.74 18.48 21.62 20.99 19.99 Average 20.42 Table 5.3 The average mean value by factor levels ( m) Factor Level A B C D 0.083 0.098 0.110 0.118 0.093 0.112 0.096 0.074 0.122 0.087 0.091 0.106 Average 0.099 Table 5.4 ANOVA table for S/N ratio for polished surface roughness Factor D.o.f SS MS F F0.1,2,2 A 18.70 7.43 9.35* 9.00 B 7.12 2.84 3.57 9.00 C - - - - - D 27.37 10.88 13.68* 9.00 Pooled to error 2.52 1.26 Total 55.73 Basing on the plot of main effects for S/N ratio and main effects, the optimal level for each factor is the combination of A1 B3 C3 D2 Consequently, the optimal parameters for AJP process are the hydraulic pressure of kg/cm2, the impact angle of 50o, the stand-off 68 distance of 15 mm, and the polishing time of 120 minutes In addition, the effect of AJP parameters on the polished surface roughness was indicated by the ANOVA technique and Fratio test The table 5.3 shows that the polishing time and hydraulic pressure significantly affects on the surface roughness in the AJP process Table 5.5 The surface roughness value of the tested specimen after verification experiment No Mean Measured surface roughness value (Ra m) 0.0440 0.0443 0.0440 0.0441 S/N ratio 27.11 The predicted S/N ratio under optimal conditions is calculated as: The predicted S/N ratio opt = 26.01 is very close to the experimental = 27.11 (about 96%) under the optimal AJP parameters 5.2 Discussion The average value of surface roughness Ra about 0.044 m is obtained from the milling surface Ra about 0.13 m The improvement of the surface quality can be clearly observed in the 100X microscope image (figure 5.3) The milling layers are almost removed from the surface 69 Figure 5.3 The surface of polished area (a) (b) Figure 5.4 The surface quality of (a) milling surface (b) polished surface For the long time and high pressure of AJP process, the surface of the workpiece was over-polished and then there were a lot of holes which is created by the high velocity abrasives The over-polished surface is showed in figure 5.3 70 Figure 5.5 The over-polished surface In contrast, for the short time and low pressure of AJP process, the milling layers could not be removed Consequently, the surface roughness improved slightly (figure 5.4) Figure 5.6 The surface roughness for short time and low pressure case The measuring value from the load cell in first minutes of polishing is showed in figure 5.7 In addition, the polishing process was conducted with the optimal parameters 71 Figure 5.7 The load cell measuring value 72 Chapter CONCLUSION AND RECOMMENDATION 6.1 Conclusion This study has conducted a series of experiments to establish the optimal parameter for the surface finishing of AJP process on the Zr-based BMG material Some of conclusion can be summarized as followed: - The optimal AJP processing parameters are the combination of the pressure of kg/cm2, the impact angle of 50o, the stand-off distance of 15 mm, and the polishing time of 60 minutes The surface roughness is improved from the initial value of Ra about 0.13 m to the value of Ra 0.044 m Furthermore, the pre-milling layers were almost removed - The polishing time and hydraulic pressure significantly affect on the polished surface roughness - The ball burnishing process is unsuitable for the BMG material because of its brittle properties 6.2 Recommendation for future work Some of recommendations for the future work are described below: - The experiments of AJP process were conducted only for factors Applying a L18 Taguchi orthogonal array with more factors will provide a better data for optimization of AJP process condition - Using the SEM instrument to observe the holes which are created by the abrasives - Using more polishing nozzles can decrease the polishing time A new design of polishing tool with more nozzles can be used to investigate the effect of the number of nozzle to the surface roughness - Grinding process can be used as the pre-machining method 73 Bibliography [1] C Suryanarayana, A Inoue, Bulk metallic glasses, CRC Press, New York, 2011 [2] M Miller, P Liaw, Bulk metallic glasses: an overview, Springer, New York, 2008 [3] M M Trexler, N N Thadhani, Mechanical properties of bulk metallic glasses, Progress in Materials Science 55 (2010) 759–839 [4] M Bakkal, A J Shih, R O Scattergood, C T Liu, Chip formation, cutting forces, and tool wear in turning of Zr-based bulk metallic glass, International Journal of Machine Tools & Manufacture 44 (2004) 915–925 [5] M Bakkal, V Nakşiler, B Derin, Machinability of bulk metallic glass materials on milling and drilling, Advanced Materials Research Vols 83-86 (2010) pp 335-341 [6] M Q Jiang, L H Dai, Formation mechanism of lamellar chips during machining of bulk metallic glasses, Acta Materialia 57 (2009) 2730–2738 [7] N H Loh, S C Tam, Effects of ball burnishing parameters on surface finish – A literature survey and discussion, Precision engineering October 1988 Vol 10 No [8] N H Loh, S C Tam, S Miyazawa, A study of the effects of ball-burnishing parameters on surface roughness using factorial design, Journal of Mechanical Working Technology, 18 (1989) 53-61 [9] N H Loh, S C Tam, S Miyazawa, Ball burnishing of tool steel, Precision Engineering Volume 15, Issue 2, April 1993, Pages 100-105 [10] L Luca, S N Ventzel, I Marinescu, Effects of working parameters on surface finish in ball-burnishing of hardened steels, Precision Engineering 29 (2005) 253–256 74 [11] F J Shiou, C H Chen, Determination of optimal ball-burnishing parameters for Plastic injection moulding steel, International Journal of Advanced Manufacture Technology (2003) 3:177–185 [12] F J Shiou, C C Hsu, Surface finishing of hardened and tempered stainless tool steel using sequential ball grinding, ball burnishing and ball polishing processes on a machining centre, Journal of Materials Processing Technology ( 0 ) 249–258 [13] F J Shiou, C H Cheng, Ultra-precision surface finish of NAK80 mould tool steel using sequential ball burnishing and ball polishing processes, Journal of Materials Processing Technology ( 0 ) 554–559 [14] F J Shiou, C H Chuang, Precision surface finish of the mold steel PDS5 using an innovative ball burnishing tool embedded with a load cell, Precision Engineering 34 (2010) 76–84 [15] H Liu, J Wang, Abrasive liquid jet as a flexible polishing tool, International Journal of Materials and Product Technology, Vol 31, No 1, 2008 [16] F Li, Experimental and numerical investigation of abrasive waterjet polishing technology, Dissertation, The New Jersey Institute of Technology, 1996 [17] S M Booji, Fluid Jet Polishing possibilities and limitations of a new fabrication technique, Dissertation, Technische Universiteit Delft, 2003 [18] H Liu, C Z Huang, J Wang, Abrasive liquid jet as a flexible polishing tool, International Journal of Materials and Product Technology, Vol 31, No 1, 2008 [19] B H Yan, F C Tsai, L W Sun, R T Hsu, Abrasive jet polishing on SKD61 mold steel using SiC coated with Wax, Journal of Materials Processing Technology ( 0 ) 318–329 75 [20] H T Zhu, C Z Huang, J Wang, Q L Lia, C L Che, Experimental study on abrasive waterjet polishing for hard–brittle materials, International Journal of Machine Tools & Manufacture 49 (2009) 569–578 [21] http://www.mfg.mtu.edu/marc/primers/milling/ [22] http://www.kanabco.com/vms/glossary/m/mill_parts.html [23] S Kalpakjian, S R Schmid, Manufacturing, Engineering & Technology, Fifth Edition, ISBN 0-13-148965-8 © 2006 Pearson Education, Inc., Upper Saddle River, NJ [24] http://www.uddeholm.com/ [25] 2001 [26] http://www.ferroceramic.com/ [27] H Fang, P Guo, J Yu, Surface roughness and material removal in fluid jet polishing, Applied Optics, Vol 45, No 17, 10 June 2006 [28] ASME B46.1-1995, Surface texture (surface roughness, waviness, and lay): an American national standard, American Society of Mechanical Engineers, New York, 1996 [29] R K Roy, Design of experiments using the Taguchi approach: 16 Steps to product and process improvement, John Wiley & Sons, Inc., New York, 2001 [30] J S C Jang, S R Jian , C F Chang, L J Chang, Y C Huang, T H Li, J C Huang, C T Liu, Thermal and mechanical properties of the Zr53Cu30Ni9Al8 base d bulk metallic glass microalloyed with silicon, Journal of Alloys and Compounds 478 (20 09) 215–219 [31] http://lubricants.petro-canada.ca/en/products/516.aspx 76 Appendix A Properties of Aluminum Oxide Abrasives [26] 77 Properties of Silicon Carbide Abrasives [26] 78 Appendix B The drawing of the fixture of BMG sample 79 Appendix C Experimental setup of the ball burnishing process [14] 80 Appendix D The properties of the MV32 hydraulic oil [31] 81 ... objective of this thesis is the study of the surface quality after the processing of milling, ball burnishing and abrasive jet polishing In addition, the effects of the AJP parameters on the surface. .. correlation between the machining and polishing conditions and the surface quality after the machining and polishing process Consequently, this thesis aims to investigate the deeper knowledge about the. .. results These optimal parameters are the combination of the hydraulic pressure of kg/cm2, the impact angle of 50o, the stand-off distance of 15 mm, and the polishing time of 60 minutes The surface