Conventional Machining of an Aluminium Based SiC Reinforced Metal Matrix Composite (MMC) Alloy

Metal Matrix Composites (MMC’s) are a new class of materials intended for high performance applications. The paper outlines the results of a series of turning, face milling, drilling, reaming and tapping tests performed on an aluminium 2618 alloy reinforced with 15 vol% silicon carbide (SiC) particulate. High speed steel, cemented tungsten carbide and polycrystalline diamond (PCD) cutting tools were used. Based on a tool life criterion PCD products proved, in general, to be the most effective and the only tool material capable of providing a realistic operating performance. For instance, when using tungsten carbide drills only 48 holes could be made before lip flank wear reached 0.6 mm. PCD tipped drills cut 300 holes with only 0.08 mm of flank wear. In turning and to some extent in face milling operations, changes in cutting speed did not significantly effect flank wear rate. In drilling and reaming feed rate proved to be the key parameter.