Machining MMC engineering components with polycrystalline diamond and diamond grinding

Abstract

The high specific strength of metal matrix composite (MMC) materials is derived from the combined effects of light, ductile and hard, brittle materials being incorporated in a matrix composite. The hard, brittle phase in this composite can cause problems when machining such materials. The most commonly encountered problems are those involved in producing an acceptable surface finish, avoiding very rapid tool wear and achieving acceptable machining costs, through the use of higher machining speeds. However, in order for MMC materials to be widely accepted into the mainstream automotive, aerospace, and mechanical engineering industries, cost effective machining solutions will be required. Increasingly, machining with polycrystalline diamond (PCD) and grinding with diamond abrasives (two examples of ultra hard materials) are being utilised as the most effective machining methods in the manufacture of MMC components. The present paper explores the inherent problems involved in the machining of MMCs and the suitability of ultrahard tooling technology in overcoming many of these problems. The importance of PCD grade selection and optimised machining conditions are particularly important when machining MMCs, and these are reviewed in detail. The versatility of PCD for use in practically all metal cutting operations is also illustrated. The paper concludes with a number of case studies demonstrating how ultrahard tooling technology has been applied to produce economically a wide range of engineered MMC components in the automotive, aerospace, and mechanical engineering industries.