DUCTILE-REGIME MACHINING OF PARTICLE-REINFORCED METAL MATRIX COMPOSITES

Abstract

ABSTRACT This paper presents research results on ultraprecision machining of metal matrix composite (MMC) composed of aluminum matrix and either SiC or A12 03 particles. Ductile-regime machining of both SiC and aluminum was evaluated to improve the surface integrity of the composite. Both polycrystal-line diamond (PCD) and single crystalline diamond (SCD) tools were used to ultraprecision machine the composites at a depth of cut ranging from 0 to 1μm using a taper cut. The feedrate was normalized to the tool nose radius. A model is proposed to calculate the critical depth of cut for MMCs reinforced with either A1203 or SiC. The critical depths of cut were found to be 1 p.m and 0.2 u.m for MMCs reinforced with A12 0 or SiC3, respectively. Both depth of cut and crystallographic direction of the ceramic particles are the sufficient conditions for ductile-regime machining. Although both tools produce similar surface finish, a SCD tool removed the MMC as chips while a PCD tool simply smeared the surface. A diffusion-abrasion mechanism was suspected to cause the surprising wear of the SCD tools when machining the aluminum/SiC composite.