MACHINING MMC ENGINEERING COMPONENTS WITH POLYCRYSTALLINE DIAMOND ANDDIAMOND GRINDING

The high specific strength of metal matrix composite (MMC) materials i s derived from the combined effects of light, ductile and hard, brittl e materials being incorporated in a matrix composite. The hard, brittl e phase in this composite can cause problems when machining such mater ials. The most commonly encountered problems are those involved in pro ducing and acceptable surface finish, avoiding very rapid tool wear an d achieving acceptable machining costs, through the use of higher mach ining speeds. However, in order for MMC materials to be widely accepte d into mainstream automotive, aerospace, and mechanical engineering in dustries, cost effective machining solutions will be required. Increas ingly, machining with polycrystalline diamond (PCD) and grinding with diamond abrasives (two examples of ultrahard materials) are being util ised 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 tec hnology in overcoming many of these problems. The importance of PCD gr ade selection and optimised machining conditions are particularly impo rtant when machining MMCs, and these are reviewed in detail. The versa tility of PCD for use in practically all metal cutting operations is a lso illustrated. the paper concludes with a number of case studies dem onstrating how ultrahard tooling technology has been applied to produc e economically a wide range of engineered MMC components in the automo tive, aerospace, and mechanical engineering. MST/4031.