CUMULATIVE TOOL WEAR IN MACHINING METAL-MATRIX COMPOSITES .2. MACHINABILITY

Models for cumulative tool wear are used to study the machinability of aluminium matrix composites reinforced with SiC or Al2O3 particles. C utting conditions to simulate a finishing operation were employed. Eff ects of cutting tool materials, heat treatment, and hot isostatic pres sing were investigated. Carbide tools can be utilized in a roughing op eration, while cubic boron nitride and polycrystalline diamond tools c ould be used to finish-machine the composites. The latter tools have a cceptable tool lives, and cause minimum damage to the sub-surface. The hard aluminium matrix as a result of heat treatment significantly sho rtens the tool life. Fractured and delaminated particles along or unde rneath a machined surface could be of concern when composites are used in critical applications.