Drilling of hybrid metal matrix composites - Workpiece surface integrity

The main concern in the present study is the surface roughness variations on the drilled surface and extension of surface and subsurface deformation due to drilling. The influence of different tools and cutting conditions on A12219/15%SiCp and A12219/15%SiCp-3%Graphite (hybrid) composites is investigated experimentally. The composites are fabricated by liquid metallurgy method. The drilling tests are conducted with carbide and coated carbide tools. The surface roughness decreases with the increase in cutting speed and increases with the increase in feed rate. The surface is analyzed using scanning electron microscope (SEM). Microhardness profiles indicate that the subsurface deformation extends up to a maximum of 120 mu m below the machined surface for A12219/15SiCp-3Gr composite when compared to 150 mu m in A12219/15SiCp composite. (C) 2006 Elsevier Ltd. All rights reserved.