A new approach for uncut detection and automatic design of EDM electrodes

Abstract

Plastic parts such as smart cellphones are becoming more compact and variable than before. The structures of injection molds, that produce those plastic parts, also become more compact and complex correspondingly. With the restriction of the cutter radius and feeding direction, the conventional milling process usually fails to process such variable structures of injection molds, and the electric discharge machining (EDM) electrodes are always employed in these cases. Although specific commercial CAD/CAM software for injection mold application is widely used in electrode design, large amounts of human–computer interactions are still needed. Thus, there is still room for improvement in the EDM electrode design. This paper presents a systematic methodology which includes uncut detection in the injection mold and automation of EDM electrode design. A toolpath simulation method is proposed to check all the faces of an injection mold to find the uncut regions that cannot be processed by all the cutters. Then, each uncut region is recursively split into sub-regions to construct an electrode with a set of CAD modeling operations. Based on diverse shapes of the sub-regions, two geometry operation methods, extruding method and cutting method, are employed to generate electrode tips. Case studies and industrial applications have demonstrated the algorithm’s powerful ability in handling complex structures of injection mold, and the efficiency for EDM electrodes design could be improved by 70% at least.