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Abstract
Aluminium Metal Matrix Composites (MMC) reinforced with ceramic particles have been increasingly developed during the last decade. Ceramic particles used as reinforcement that improve the wear resistance of composites also cause high abrasive wear on cutting tools. This thesis investigates the machinability of graphitic MMC consisting of an aluminium alloy matrix reinforced with both soft nickel-coated graphite particles and hard (SiC or Al2O 3) particles. These composites were developed seven years ago, but the lack of optimised machining data to machine GrA-NI® composites cost effectively have been slowing down their use in engineering applications.
Turning, milling and drilling tests were performed to evaluate the machinability of different GrA-NI® and to establish cutting conditions. It was found that: (1) The machinability of GrA-Ni® composites depends on the nature and the percentage of the reinforcing particles. GrA-Ni® containing alumina and graphite are easier to machine than those reinforced with silicon carbide and graphite. (2) Polycrystalline (PCD) and diamond-coated carbide (DCC) are the tool material of choice for machining GrA-Ni®. DCC tools are most cost effective while PCD tools produce better part finishes. (3) The cutting force required to machine the GrA-NI® composites is similar to that used for aluminium alloys such as Al 380.
