Surface Characteristics of Tool Steel Machined Using Micro-EDM

  • Anwar, Mohammed Muntakim (Department of Mechanical Engineering, National University of Singapore) ;
  • San, Wong Yoke (Department of Mechanical Engineering, National University of Singapore) ;
  • Rahman, Mustafizur (Department of Mechanical Engineering, National University of Singapore)
  • 발행 : 2008.10.01

초록

High-speed tool steels are extensively used in tooling industries for manufacturing cutting tools, forming tools, and rolls. Electrical discharge machining (EDM) has been found to be an effective process for machining these extremely hard and difficult-to-cut materials. Extensive research has been conducted to identify the optimum machining parameters for EDM with different tool steels. This paper presents a fundamental study of the surface characteristics of SKH-51 tool steel machined by micro-EDM, with particular focus on obtaining a better surface finish. An RC pulse generator was used to obtain a better surface finish as it produces fine discharge craters. The main operating parameters studied were the gap voltage and the capacitance while the resistance and other gap control parameters were kept constant. A negative tungsten electrode was used in this study. The micro-EDM performance was analyzed by atomic force microscopy to determine the average surface roughness and the distance between the highest peak and lowest valley. The topography of the machined surface was observed using a scanning electron microscope and a digital optical microscope.

키워드

참고문헌

  1. Puertas, I. and Luis, C. J., 'A study on the machining parameters optimization of electrical discharge machining,' Journal of Materials Processing Technology, Vol. 143-144, pp. 521-526, 2003 https://doi.org/10.1016/S0924-0136(03)00392-3
  2. Masuzawa, T., 'State-of-the-art on micromachining,' Annals of the CIRP, Vol. 49, No. 2, p. 473, 2000 https://doi.org/10.1016/S0007-8506(07)63451-9
  3. Singh, S., Maheshwari, S. and Pandey, P. C., 'Some investigations into the electrical discharge machining of hardened tool steel using different electrode materials,' Journal of Materials Processing Technology, Vol. 149, Issues 1-3, pp. 272-277, 2004 https://doi.org/10.1016/j.jmatprotec.2003.11.046
  4. Amorim, F. L. and Weingaertner, W. L., 'The influence of generator actuation mode and process parameters on the performance finish EDM of a tool steel,' Journal of Materials Processing Technology, Vol. 166, Issue 3, pp. 411-416, 2003 https://doi.org/10.1016/j.jmatprotec.2004.08.026
  5. Guu, Y. H., 'AFM surface imaging of AISI D2 tool steel machined by the EDM process,' Applied Surface Science, Vol. 242, Issues 3-4, pp. 245-250, 2005 https://doi.org/10.1016/j.apsusc.2004.08.028
  6. 'What are the advantages in using punch industry's SKH-51 products (high speed steel),' http://www.punch.co.jp/english/en-topf.htm, 2007
  7. Lim, H. S., Wong, Y. S., Rahman, M. and Lee, E. M. K., 'A study on the machining of high-aspect ratio micro-structures using micro EDM,' Journal of Materials Processing Technology, Vol. 140, Issues 1-3, pp. 318-325, 2003 https://doi.org/10.1016/S0924-0136(03)00760-X
  8. Tsai, Y., Masuzawa, T., 'An index to evaluate the wear resistance of the electrode in micro-EDM,' Journal of Materials Processing Technology, Vol. 149, Issues 1-3, pp. 304-309, 2004 https://doi.org/10.1016/j.jmatprotec.2004.02.043
  9. Lee, H. T., Rehbach, W. P., Tai, T. Y. and Hsu, F. C., 'Relationship between electrode size and surface cracking in the EDM machining process,' Journal of Materials Science, Vol. 39, No. 23, pp. 6981-6986, 2004 https://doi.org/10.1023/B:JMSC.0000047541.95138.17
  10. Habib, M. A., Gan, S. W., Lim, H. S. and Rahman, M., 'Fabrication of EDM electrodes by Localized Electrochemical Deposition,' International Journal of Precision Engineering and Manufacturing, Vol. 9, No. 2, pp. 75-80, 2008
  11. Egashira, K., Matsugasako, A., Tsuchiya, H. and Miyazaki, M., 'Electrical discharge machining with ultralow discharge energy,' Precision Engineering, Vol. 30, Issue 4, pp. 414-420, 2006 https://doi.org/10.1016/j.precisioneng.2006.01.004
  12. Masuzawa, T., 'Micro-EDM,' Proceedings of the 13th International symposium for electromachining, Vol. 1, pp. 3-20, 2001
  13. Wong, Y. S., Rahman, M., Lim, H. S., Han, H. and Ravi, N., 'Investigation of micro-EDM material removal characteristics using single RC-pulse discharges,' Journal of Materials Processing Technology, Vol. 140, Issues 1-3, pp. 303-307, 2003 https://doi.org/10.1016/S0924-0136(03)00771-4
  14. Jung, J., Ko, S. H., Jeong, Y. H., Min, B. K. and Lee, S. J., 'Estimation of material removal volume of a micro-EDM drilled hole using discharge pulse monitoring,' International Journal of Precision Engineering and Manufacturing, Vol. 8, No. 4, pp. 45-49, 2007
  15. Han, F., Wachi, S. and Kunieda, M., 'Improvement of machining characteristics of micro-EDM using transistor type isopulse generator and servo feed control,' Precision Engineering, Vol. 28, Issue 4, pp. 378-385, 2004 https://doi.org/10.1016/j.precisioneng.2003.11.005