A study on electrode wear sensing and compensation in Micro-EDM using machine vision system

This paper presents an electrode wear compensation method based on a machine vision system for micro-electro-discharge machining (EDM). Front wear and corner wear of tool electrode can be measured and evaluated in a direct manner by the vision system's image-processing software capabilities. Tool electrode images have depicted that the front wear and corner wear were increased rapidly during EDM drilling and EDM milling, respectively, and thus contributing to an arc and a tapering shape at the end of tool electrode, respectively. Both the depth of the hole and depth of the groove are linearly proportional to the length of the front wear. A new electrode wear compensation method is presented based on the direct measurement of the front wear. Experimental results not only verify the usefulness of the electrode wear compensation method in micro-EDM, they also demonstrate that the machining time can be significantly reduced by 40% when using the proposed method, compared to the uniform wear method.