Review on tools and tool wear in EDM

Abstract

Electric discharge machining (EDM) is a nontraditional machining process based on the thermal erosion of the electrically conductive workpiece and tool electrodes. The product cost manufactured by the EDM process mainly depends on the tooling cost, which comprises the cost of tool material, tool fabrication, and tool maintenance. The properties of tool material affect the machining performance parameters like material removal rate (MRR), tool wear rate (TWR), and surface roughness. The performance parameters are also influenced by the tool geometry, tool fabrication method, and the way by which both tools and workpiece interact with each other. In the EDM process, tool wear is difficult to avoid and high TWR decreases the accuracy of the machined parts. Therefore, to obtain the desired accuracy it is necessary to calculate TWR and provide wear compensation. The tool electrode fabrication method also decides the TWR. Tool electrodes are generally manufactured by metal forming techniques like forging and drawing, other than that, powder metallurgy, additive manufacturing are also being used. The process performance of the tool can be improved by cryogenic treatment and coating of the tool electrodes. This review provides the literature survey about the different types of tools used in the EDM process, methods of fabrication, tool wear types; measurement and compensation techniques.