Micro Electro Discharge Machining for Nonconductive Ceramic Materials

  • Mohammad Yeakub Ali International Islamic University Malaysia
  • Abdus Sabur International Islamic University Malaysia
  • Asfana Banu International Islamic University Malaysia
  • Md. Abdul Maleque International Islamic University Malaysia
  • Erry YT Adesta International Islamic University Malaysia

Abstract

In micro-electro discharge machining (micro-EDM) of nonconductive ceramics, material is removed mainly by spalling due to the dominance of alternating thermal load. The established micro-EDM models established for single spark erosion are not applicable for nonconductive ceramics because of random spalling. Moreover, it is difficult to create single spark on a nonconductive ceramic workpiece when the spark is initiated by the assisting electrode. In this paper, theoretical model of material removal rate (MRR) as the function of capacitance and voltage is developed for micro-EDM of nonconductive zirconium oxide (ZrO2). It is shown that the charging and discharging duration depend on the capacitance and resistances of the circuit. The number of sparks per unit time is estimated from the single spark duration s derived from heat transfer fundamentals. The model showed that both the capacitance and voltage are significant process parameters where any increase of capacitance and voltage increases the MRR. However, capacitance was found to be the dominating parameter over voltage. As in case of higher capacitances, the creation of a conductive carbonic layer on the machined surface was not stable; the effective window of machining 101 - 103 pF capacitance and 80 - 100 V gap voltage or 10 - 470 pF capacitance and 80 - 110 V gap voltage. This fact was confirmed EDX analysis where the presence of high carbon content was evident. Conversely, the spark was found to be inconsistent using parameters beyond these ranges and consequently insignificant MRR. Nevertheless, the effective number of sparks per second were close to the predicted numbers when machining conductive copper material. In addition, higher percentage of ineffective pulses was observed during the machining which eventually reduced the MRR. In case of validation, average deviations between the predicted and experimental values were found to be around 10%. Finally, micro-channels were machined on nonconductive ZrO2 as an application of the model.

References

REFERENCES
1. Ji, R., Liu, Y., Zhang, Y., Wang, F., Chen, Z., & Dong, X. (2011). Study on single-discharge machining characteristics of non-conductive engineering ceramics in emulsion with high open voltage and large capacitor. Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture, 225(10), 1888-1898.
2. Hösel, T., Cvancara, P., Ganz, T., Müller, C., & Reinecke, H. (2011). Characterisation of high aspect ratio non-conductive ceramic microstructures made by spark erosion. Microsystem Technologies, 17(2), 313-318.
3. Hösel, T., Müller, C., & Reinecke, H. (2011). Spark erosive structuring of electrically nonconductive zirconia with an assisting electrode. CIRP Journal of Manufacturing Science and Technology, 4(4), 357-361.
4. Chevalier, J., & Gremillard, L. (2009). Ceramics for medical applications: A picture for the next 20 years. Journal of the European Ceramic Society, 29(7), 1245-1255.
5. Yoo, B. H., Min, B.-K., & Lee, S. J. (2010). Analysis of the machining characteristics of EDM as functions of the mobilities of electrons and ions. International Journal of Precision Engineering and Manufacturing, 11(4), 629-632.
6. Dhanik, S., & Joshi, S. S. (2005). Modeling of a single resistance capacitance pulse discharge in micro-electro discharge machining. Journal of Manufacturing Science and Engineering, 127(4), 759-767.
7. Salonitis, K., Stournaras, A., Stavropoulos, P., & Chryssolouris, G. (2009). Thermal modeling of the material removal rate and surface roughness for die-sinking EDM. The International Journal of Advanced Manufacturing Technology, 40(3-4), 316-323.
8. Zahiruddin, M., & Kunieda, M. (2012). Comparison of energy and removal efficiencies between micro and macro EDM. CIRP Annals-Manufacturing Technology, 61(1), 187-190.
9. Liu, Y., Yu, L., Xu, Y., Ji, R., & Li, Q. (2009). Numerical simulation of single pulse discharge machining insulating Al2O3 ceramic. Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture, 223(1), 55-62.
10. Schubert, A., Zeidler, H., Wolf, N. & Hackert, M. (2011). Micro electro discharge machining of electrically nonconductive ceramics. In AIP Conference Proceedings, 1353, 1303.
11. Wong, Y., Rahman, M., Lim, H., Han, H., & Ravi, N. (2003). Investigation of micro-EDM material removal characteristics using single RC-pulse discharges. Journal of Materials Processing Technology, 140(1), 303-307.
12. Kunieda, M., Lauwers, B., Rajurkar, K. P., & Schumacher, B. M. (2005). Advancing EDM through fundamental insight into the process. CIRP Annals-Manufacturing Technology, 54(2), 64-87.
13. Shin, H. S., Park, M. S., & Chu, C. N. (2011). Machining characteristics of micro EDM in water using high frequency bipolar pulse. International Journal of Precision Engineering and Manufacturing, 12(2), 195-201.
14. Lim, H., Wong, Y., Rahman, M., & Edwin Lee, M. (2003). A study on the machining of high-aspect ratio micro-structures using micro-EDM. Journal of Materials Processing Technology, 140(1), 318-325.
15. Jahan, M., Wong, Y., & Rahman, M. (2009). A study on the fine-finish die-sinking micro-EDM of tungsten carbide using different electrode materials. Journal of Materials Processing Technology, 209(8), 3956-3967.
16. Kumar, S., Singh, R., Singh, T., & Sethi, B. (2009). Surface modification by electrical discharge machining: A review. Journal of Materials Processing Technology, 209(8), 3675-3687.
17. Liow, J. (2009). Mechanical micromachining: A sustainable micro-device manufacturing approach? Journal of Cleaner Production, 17(7), 662-667.
18. Yan, M.-T., & Lin, S.-S. (2011). Process planning and electrode wear compensation for 3D micro-EDM. The International Journal of Advanced Manufacturing Technology, 53(1-4), 209-219.
19. Mohri, N., Fukuzawa, Y., Tani, T., Saito, N., & Furutani, K. (1996). Assisting electrode method for machining insulating ceramics. CIRP Annals-Manufacturing Technology, 45(1), 201-204.
20. Liu, Y., Li, X., Ji, R., Yu, L., Zhang, H., & Li, Q. (2008). Effect of technological parameter on the process performance for electric discharge milling of insulating Al2O3 ceramic. Journal of Materials Processing Technology, 208(1), 245-250.
21. Liu, Y., Ji, R., Li, X., Yu, L., Zhang, H., & Li, Q. (2008). Effect of machining fluid on the process performance of electric discharge milling of insulating Al2O3 ceramic. International Journal of Machine Tools and Manufacture, 48(9), 1030-1035.
22. Sabur, A., Moudood, A., Ali, M. Y., & Maleque, M. A. (2014). Effect of micro-EDM parameters on material removal rate of nonconductive ZrO2 ceramic. Applied Mechanics and Materials, 465, 1329-1333.
Published
2018-03-30
Section
Articles