LASER-ASSISTED PRODUCTION OF ELECTRICAL DISCHARGE MACHINING (EDM) ELECTRODES: A COMPARATIVE STUDY BETWEEN RAPID PROTOTYPING BY SELECTIVE LASER SINTERING AND LASER SURFACE CLADDING TECHNIQUES

摘要

Electrical discharge machining (EDM) is a simple and efficient process for the fabrication of complex dies or moulds. However, the electrodes employed for EDM are usually difficult to be produced, being the major cost and time-consuming part of EDM, reaching more than 50% of the total machining cost. The processes of rapid prototyping by laser cladding with lateral powder injection and by selective laser sintering were considered in this work to fabricate EDM electrodes. The electrodischarge machining electrode requirements are high metal removal rate, high wear resistance and a good surface finish. Moreover, the application of rapid prototyping leads to reduction in the electrode production time, being helpful to decrease the overall processing costs of the well established electrodischarge machining process, and also allows manufacturing electrodes with complex geometry. Copper matrix composite electrodes were produced by Nd:YAG, and CO_2 laser. The results obtained with both rapid prototyping techniques were characterized in terms of geometric accuracy, microstructure, hardness and composition by means of interferometric profilometry, electron scanning microscopy, energy dispersive X-ray spectroscopy, and X-Ray diffraction.