On machine measurements of electrode wear in micro EDM milling

The electrode wear in micro electrical discharge milling (micro EDM milling) is one of the main problems to be solved in order to improve machining accuracy. Most common, the electrode wear is measured on machine by touching the reference point with the tip of the electrode (Touch method) after machining a certain number of layers. The reduction of the electrode length due to the wear (linear wear) is used to modify the electrode trajectory. A laser scan micrometer (LSM) is implemented on the machine mostly to acquire electrode profiles after dressing of the electrode is applied. It is also an alternative solution to measure the linear and volumetric wear, which in principle should be more accurate compared to the measurements performed by The Touch method. In this paper, the performance of the two systems, namely Touch and LSM, were compared. The experimental results show that the accuracy of the electrode length measurement by the Touch method is enough accurate for the linear wear estimation, but the volumetric wear should be measured by LSM system.