Study of Dry EDM Milling Integrated with Electrode Wear Compensation and Finishing

An experimental investigation of electrical discharge machining milling in gas combined with electrode wear compensation and finish machining is reported in this work. Comparative experiments using compressed air and kerosene demonstrated that dry electrical discharge machining (EDM) milling (EDMM) exhibits a higher processing precision than conventional EDMM as a consequence of low electrode wear. Nevertheless, appropriate electrode wear compensation is necessary under certain conditions. Considering the requirements of finishing and the presence of the electrode wear in dry EDMM (DEDMM), a decomposition segmental machining approach addressing both electrode wear compensation and finishing is proposed. Finish machining is achieved by running each numerical control (NC) program segment developed in this study twice to avoid an uneven gas distribution. The electrode wear is compensated by redefining the reference point coordinates relative to the start point coordinates using NC codes in each segment. DEDMM experiments verified the feasibility of the approach. The advantages of the method include small accumulative error, no wear calculation, and easy operation. This approach can potentially be applied to other types of EDMM because of its flexibility.