Electrical Discharge Machining (EDM) of High-Performance Ceramics

Abstract

Important and high value adding applications of modern structural ceramics are in the field of tools and dies in manufacturing engineering. That is, processing of highly abrasive materials in powder injection molding or extrusion requires mold materials with high wear resistance to increase the durability of the tools and to sustain a high quality of the manufactured products. High-performance ceramics, which exhibit high hardness, bending strength, and toughness, features the perfect combination of properties for these applications. Their drawback is that they cannot be economically customized in complex shapes and small lot sizes, as they are required in tool and mold design. Recent development of electrically conductive oxide ceramics enabled the use of EDM, the most used process for machining of hard materials, as an alternative to conventional ceramic manufacturing technologies. By combining the shaping and final machining of ceramics by EDM in one process step, complex shaped assemblies with fine structures, small tolerances, and the benefits of ceramic material properties can produced. The focus is on ZTA-based ceramics with the addition of titanium carbide that can be machined by wire-EDM and die sinking. Mechanical and electrical properties of the materials as well as the characteristics of the machining process and its influence on the workpiece material are analyzed. Additionally, the feasibility of the ceramic material for tool inserts is shown by real wear tests in extrusion dies.