Diamond slide burnishing for the finishing of electrical discharge machined surfaces

Electrical discharge machining (EDM) represents a key manufacturing technology in a broad range of industries, e. g. aerospace, automotive and mould making. Current industrial and scientific relevant challenges are long machining times to achieve the surface roughness values needed, excessive tool electrode wear and the related huge number of tool electrodes needed. At state of the art, the challenges mentioned strongly limit the economic efficiency of precision EDM processes. To overcome these major challenges, the substitution of time consuming EDM polishing processes by diamond slide burnishing (DSB) shows great potential. During the process, a monocrystalline spherical diamond burnishing tool is moved along the surface of the workpiece with a defined process force. In this way the surface is specifically compressed and roughness peaks are smoothed. Within this work the applicability of diamond slide burnishing for the finishing of electrical discharge machined surfaces was investigated. For this purpose, three VDI grades with different surface roughness values were subsequently machined by DSB. The results show that the surfaces with different initial surface conditions can be successfully finished by DSB. The surface roughness of VDI grade 30 is identified as an upper limit for the surface preparation by EDM. A significant improvement of the surface roughness Ra by 93 % and a reduction of the processing time by 40 % could be achieved by the post-processing using DSB. Therefore, the new process chain presented shows great potential for being used in the field of tool and mould making and especially for the production of injection moulds.