A Case Study of Multiple-Use Finish Electrodes for Die-Sinking EDM

摘要

This study examines the use of one finishing electrode to finish multiple dies without remachining the electrode. The multiple-use electrode finishing experiment in this study addresses technology in the die-forging industry. Methods of manufacturing spherical straight bevel forge gear dies have relied on die-sinking Electrical Discharge Machining (EDM) practices that showed great potential for advancement. The focus of this study is solely on the improvements of electrode use in EDM finishing-processes. The surface finish quality itself is not an area of concern other than maintaining that it does not diminish. The focused concern is maximizing the process by using one electrode unmodified for multiple-finishing operations. The objective for improvement is utilization of one finishing electrode used multiple times rather than only one finishing electrode per die. Utilizing a Coordinate Measuring Machine (CMM), the inspection of specific locations on the finishing electrode reveals the repeatability and accuracy of use for one finishing electrode for six gear forging-dies. Initial experimentation validates the capabilities to finish four dies accurately in two separate die configurations with one electrode. To accomplish finishing the four initial dies, a die-sinking EDM machine that possesses a large enough working envelope was included in the process. The transition of using graphite electrode materials in place of brass for finishing multiple dies aids in reducing what was a total eight-hour process time into a four-hour process time.A machine with a working envelope large enough for only setting up one die to be EDM machined generated the eight-hour process time. The researcher achieved the eight-hour process time by replacing brass electrodes in the roughing stages with graphite electrodes. The extent to which one finish electrode can finish a sample set of six complete dies with one electrode is studied. Data is extrapolated from the deviation of absolute locations on a three-dimensional solid model compared to the multiple-use finishing electrode. Specific locations inspected on the electrode conclude the study efforts with results revealing that the maximum repeated use of an electrode is seven uses.