Development of a machining strategy for diamond slide burnishing burnishing tools made of polycrystalline diamond (PCD)

摘要

High demands on product quality force companies to reduce production costs. Due to the growing international competition, optical surfaces for tool and mould making need to be produced economically. These surfaces are commonly produced using ultra-precision cutting. However, the efficiency is limited due to low feed velocities V_f, small depth of cut a_p and associated long process times tp_r. An innovative manufacturing process represents diamond burnishing, which can be carried out directly after the high-precision milling process. For this purpose, super-hard materials made of single crystalline diamond (SCD) are currently used as tool materials. Since the material costs are high and the availability is limited, SCD needs to be substituted. An innovative substitution material is polycrystalline diamond (PCD). Within this paper, a machining strategy for the high-precision production of PCD spheres for diamond slide burnishing tools is presented. The processes grinding, polishing and electrical discharge machining (EDM) were applied. Therefore, the manufacturing costs, the surface roughness, the shape accuracy as well as the concentricity accuracy were analysed. Based on these investigations, an efficient and economical machining strategy for the production of high-precision spherical geometries made of PCD can be provided. First results showed that the prefered machining strategy uses a cross-process chain consisting of grinding and polishing. Thereby, the advantages of both processes with the fast manufacturing of the macro-geometry by the grinding process as well as the high surface qualities, which can be achieved by the polishing process, are combined.