Study Of Tool Wear Compensation Method Based On Meshing For Micro EDM Milling

Nowadays, the demand for micro structures and micro molds is increasing, which in turn greatly promotes the development of micro fabrication techniques. As one of these techniques, micro electrical discharge machining (EDM) attracts more and more attention from industries due to its unique wide range of material processing applicability. Sometimes, it is the only solution to generate micro holes with high aspect ratio and complex micro shapes in electrically conductive materials.Complex3D micro-structures can be machined layer by layer in alloys by micro EDM using simple shaped electrodes. However, electrode wear is a serious problem which significantly affects machining accuracy. The electrode wear compensation method is a key issue in micro EDM milling and effective solution to this problem. This paper proposed a new tool wear compensation method based on grid meshing in each layer machining, this method not only effectively solves the unstable machining problem in UWM (Uniform Wear Method) that caused by compensating the tool wear with one feed at the beginning of each layer, but also eliminates the inaccurate or wrong compensation in CLU (Combination of Linear compensation with UWM) due to ignoring the overlap area between adjoin tool paths. Using the proposed method, the discharge gap is maintained within an appropriate range all the time because of the immediate compensation for electrode wear, which makes the processing more stable and efficient. To generate3D micro cavities, the new method is integrated with a CAD/CAM system. Experimental results of the proposed method have been compared with those using UWM and using CLU. It was found that the machining efficiency was improved and tool wear ratio (TWR) was reduced using the proposed method.Besides, a set of numerical control program has been designed for micro EDM milling, including the functions of online electrode fabrication, three dimensional milling, NC codes displaying, online tool path displaying and voltage data recording. Finally, several complex micro cavities were fabricated to verify the applicability of the proposed compensation method.