عنوان مقاله [English]
In this paper, the effect of the tool’s material and the workpiece rotational speed on the near dry electrical discharge machining (N.D-EDM) has been studied. In order to, three levels of the workpiece rotational speed and the discharge current are used for evaluating material removal rate (MRR), tool wear rate (TWR) and surface roughness (SR). After doing the experimental study and getting the appropriate speed, a comparison has been done between the fixed and rotary workpiece N.D-EDM. Finally, another comparison has been done between the fixed workpiece N.D-EDM with CO2 gas and the submerged EDM. The results show that the rotational speed of 600 rpm cause to increase in material removal rate, tool wear rate and the reduction in surface roughness. In addition to, the comparison between rotary and fixed workpiece N.D-EDM explain that rotary state have the higher rank of efficency. Due to the low level of electrical resistivity of copper tool, it has the highest MRR and by increasing the discharge current, the highest TWR than other tools. Also, the surface roughness of the workpiece in the fixed N.D-EDM is less than submerged EDM.
 C. P. Patel, K. R. Modi, and M. G. Bhatt, "A Review on optimization of Dry Electro Discharge Machining Process Parameters", International Journal for Scientific Research & Development, Vol. 1, NO. 9, 2013, pp. 1901– 1904.
 M. Kunida, M. Yoshida, and N. Taniguchi, "Electrical Discharge Machining in gas", CIRP Annals-Manufaturing Technology, Vol. 46, NO. 1, January 1997, pp. 143 – 146.
 R. Roth, H. Balzer, F. Kuster, and K. Wegener, "Influence of the anode material on the breakdown behavior in dry electrical eischarge machining", In 5th CIRP Conference on High Performance Cutting 2012, Vol. 1, 2012, pp. 639– 644.
 R. Roth, F. Kuster, and K. Wegener, "Influence of oxidizing gas on the stability of dry electrical discharge machining process", Procedia CIRP, Vol. 6, January 2013, pp. 338– 343.
 G. Skrabalak, J. Kozak, and M. Zybura, "Optimization of dry EDM milling process", Procedia CIRP, Vol. 6, January 2013, pp. 332– 337.
 J. Tao, "Investigation of dry and near-dry electrical discharge machining processes", PhD Thesis, University of Michigan, Japan, 2008.
 C. C. Kao, J. Tao, and A. J. Shih, "Near dry electrical discharge machining", International Journal of Machine Tools and Manufacture, Vol. 47, NO. 15, December 2007, pp. 2273– 2281.
 J. Tao, and A. J. Shih, "Experiment Study of the Dry and Near-Dry Electrical Discharge Milling Processes", Journal of Manufacturing Science and Engineering, Vol. 130, NO. 1, February 2008, pp. 1 – 11.
 A. Gholipoor, H. Baseri, and M. Shakeri, "Experimental investigation of near dry EDM process", Modares Mechanical Engineering, Vol. 14, NO. 1, 2014, pp. 106– 112.
 X. Bai, Q. Zhang, J. Zhang, D. Kong, and T. Yang, "Machining efficiency of powder mixed near dry electrical discharge machining based on different material combinations of tool electrode and workpiece electrode", Journal of Manufacturing Processes, Vol. 15, NO. 4, October 2014, pp. 474– 482.
 X. Bai, Q. Zhang, J. Zhang, D. Kong, and T. Yang, "Research on material removal rate of powder mixed near dry electrical discharge machining", The international journal of Advanced manufacturingTechnology, Vol. 68, NO. 5-8, September 2013, pp. 1757– 1766.
 A. Gholipoor, H. Baseri, and M. R. Shabgard, "Investigation of near dry EDM compared with wet and dry EDM processes", Journal of Mechanical Science and Technology, Vol. 29, NO. 5, May 2015, pp. 363 – 367.
 M. H. Sadeghi, M. J. Hadad, T. Tawakoli, A. Vesali, and M. Emami, "An investigation on surface grinding of AISI 4140 hardened steel using minimum quantity lubrication-MQL technique", International Journal of Material Forming, Vol. 3, NO. 4, December 2010, pp. 241– 251.
 A. Bahadori, "Thermal Insulation Handbook for the Oil, Gas, and Petrochemical Industries", Edition.1, Gulf professional publishing, New York, March 2014, pp. 144.
 C. L. Yaws, "Handbook of Transport Property Data: Viscosity, Thermal Conductivity, and Diffusion Coefficients of Liquids and Gases", Gulf Publishing Company, Houston, 1995.
 S. Joshi, P. Govindan, A. Malshe, and K. Rajurkar, "Experimental characterization of dry EDM performed in a pulsating magnetic field", IEEE Transactions on Energy Conversion, Vol. 60, NO. 1, January 2011, pp. 239– 242.