Experimental Investigation on Magnetic Field Assisted PMEDM Process for Slot Cutting

Abstract

In todays evolving world many new hard, difficult to machine materials are being developed. With the development of these materials the need to machine them also emerges. In order to machine theses materials many methods are being developed EDM is one of them. Electric discharge machining (EDM) is one of the maximum commonly used nontraditional processes for making accurate intricate shapes on hard materials like die steels and is most preferred process to be followed for die and mold making. Besides machining, EDM when used with powder suspension and with certain combination of electrode materials has also been helpful in developing properties like increasing surface roughness and hardness. Experiment plan has been designed using Taguchi technique to study the effect of different parameters and their levels by conducting least number of experiments. Based on this L18 orthogonal array is been used. As the most popularly used materials in die and mold casting industries are the die steels hence for this work AISI H11, H13 and D3 die steels are used as the workpiece materials for slot cutting. Effort has been made to find out the optimum machining conditions by varying process parameters like current, powder to be suspended in dielectric, its concentration, tool material and pulse-on duration at three levels with and without using external magnetic field. The results are analyzed using analysis of variance (ANOVA) both analytically and graphically. Significant factors affecting the output parameters have been found using F-test and percentage contribution. From the experimental investigation copper tool followed by C18000 tool has been found to give the best MRR results and high tool wear, whereas tungsten tool has been found to give the least MRR accompanied by least tool wear. The dimensional accuracy of the tools in terms of corner wear, side wear and overcut has also been studied.