Experimental investigation of the effect of tool material on the performance of AISI 4140 steel in the rotary near dry electrical discharge machining

This research conducts in three sections. The first section studies the effect of tool materials and gases on rotary workpiece electrical discharge machining. During the experiments, the effects of three kinds of tool materials (Cu, Cu-Cr, and Cu-Sn) and three types of industrial gases (air, argon, and CO2) on the material removal rate, tool wear rate, and workpiece surface roughness are investigated. The second is a comparison between rotary workpiece, rotary tool, and the fixed workpiece by choosing the appropriate tool material and gas in order to observe the effect of workpieces rotation on the process. Finally, another comparison has been done between wet electrical discharge machining and near dry electrical discharge machining of the fixed workpiece in order to study the effect of the dielectric. The results show the copper tool has the best performance compared with other tools. Scanning electron microscopy output shows the Cu-Sn tool creates shallow micro-cracks on the surface. Air and CO2 gases have the higher material removal rate in low current, but argon has better function than other gases in high current. In addition, a rotational speed causes an increase in material removal rate and tool wear rate and surface roughness decrease in near dry electrical discharge machining. The level of tool wear rate has decreased by 14% in the rotary workpiece compared with the rotary tool.

Study on the Influence of Metallic Powder in Near-Dry Electric Discharge Machining

Near-dry electrical discharge machining (ND-EDM) is an eco-friendly process. In this study, an approach has been made to make the machining process more efficient than ND-EDM with the addition of metallic powder with the dielectric medium to machine EN-31 die steel. Powdermixed near-dry EDM (PMND-EDM) has several advantages over the ND-EDM or conventional electrical discharge machining (EDM) process, such as a higher material removal rate (MRR), fine surface finish (Ra), sharp cutting edge, lesser recast layer, and lower deposition of debris. The output response variables are MRR, Ra, residual stress (RS) and micro-hardness (MH) of the machined surfaces. Further study of the workpiece was performed, and a comparative study was conducted between ND-EDM and PMND-EDM. In this proposed method of machining, the MRR, Ra, and MH increased by 17.85 %, 16.36 %, and 62.69 % while RS was reduced by 56.09 %.

Optimum Control Parameters During Machining of LM13 Aluminum Alloy Under Dry Electrical Discharge Machining (EDM) With A Modified Tool Design

Dry Electrical Discharge Machining (EDM) is considered as a green manufacturing process in which the liquid dielectric medium is replaced by a high velocity gas, which results improved process stability. A special tool design is adopted to find the optimum control parameters during machining of LM13 Aluminum alloy under dry EDM mode. The drilled and slotted cylindrical copper rod is used as a tool. Discharge current (I), voltage (V), pressure (P) and pulse on time (TON) are considered as varying input process parameters and duty factor and tool rotational speed are chosen at the fixed level. Taguchi L27 orthogonal array is used to design the experiment and the experiments are conducted accordingly. The experimental results are analyzed using Grey Relational Analysis to find the optimal combination of the process parameters. Also, ANOVA test is conducted to ensure the conformity of the simulation results. Pulse on time is found as the most significant parameter which is followed by voltage. Furthermore, the parameters with the highest relational grade (4 A, 200 μs, 60 V and 1.5 kPa) are used in experiment to validate the simulation results. The simulation and experimental results have a good agreement with less than 0.5 % error.