Development of a micro diamond grinding tool by compound process

This study presents a novel micro-diamond tool which is 100 mu m in diameter and that allows precise and micro-grinding during miniature die machining. A novel integrated process technology is proposed that combines "micro-EDM" with "precision composite electroforming" for fabricating micro-diamond tools. First, the metal substrate is cut down to 50 mu m in diameter using WEDG, then, the micro-diamonds with 0-2 mu m grain is "plated" on the surface of the substrate by composite electroforming, thereby becoming a multilayer micro-grinding tool. The thickness of the electroformed layer is controlled to within 25 mu m. The nickel and diamond form the bonder and cutter, respectively. To generate good convection for the electroforming solution, a partition designed with an array of drilled holes is recommended and verified. Besides effectively decreasing the impact energy of the circulatory electroforming solution, the dispersion of the diamond grains and displacement of the nickel ions are noticeably improved. Experimental results indicate that good circularity of the diamond tool can be obtained by arranging the nickel spherules array on the anode. To allow the diamond grains to converge toward the cathode, so as to increase the opportunity of reposing on the substrate, a miniature funnel mold is designed. Then the distribution of the diamond grains on the substrate surface is improved. A micro-ZrO2 ceramic ferrule is grinded to verify the proposed approach. The surface roughness of R-a = 0.085 mu m is obtained. It is demonstrated that the micro-diamond grinding tool with various outer diameters is successfully developed in this study. The suggested approach, which depends on machining applications, can be applied during the final machining. Applications include dental drilling tools, precision optic dies, molds and tools, and biomedical instruments. (C) 2009 Published by Elsevier B.V.