Multi-response Optimization of Dry EDM with Different Mediums Using the Taguchi Based Grey Relational Analysis

Dry electrical discharge machining is a sustainable machining process that is used gas medium such as air or Nitrogen instead of liquid dielectric mediums that are mainly based on oil derivation. In the current research, first each of three main responses including material removal rate (MRR), surface roughness (Ra) and radial overcut (ROC) have been optimized considering the effects of six main input factors including current (I), pulse on time (Ton), duty factor (D), spindle rotational speed (N), gas pressure (P) and the gas type.. Regarding the input factors, there are five quantitative and one qualitative input factor (gas type). So, in addition of air as most common dielectric medium, Nitrogen and mixture of Argon and air have been investigated as the other input factors of this parameter. The main purpose of this study is the multi objective optimization of dry electrical discharge machining responses by using the Grey relational analysis based on the Taguchi method. The results of this optimization method show the optimized level at I=12A, Pulse on time (Ton)=100 s , Duty factor (D) =66, Gas Pressure (P) = 3 bar and Spindle rotational speed (N)= 300 rpm and Nitrogen as the dielectric medium. The confirmation experiment at the optimized level by this method depicts that the optimized level has the maximum grey grade, hence it confirms the accuracy of the optimized level by Grey Relational Analysis method.. Also, regarding the equal weights of responses and considering the same effects of the surface roughness and radial over cut that both of them have the smaller the better characteristics, the optimization results in more effect on these responses in comparison with material removal rate.