MACHINABILITY STUDIES ON ALUMINIUM BASED METAL MATRIX COMPOSITES

Abstract

Metal matrix composites (MMCs) are replacing many conventional materials because of their superior properties such as high toughness, high specific strength, workability at elevated temperature, high stiffness etc. Metal matrix composites (MMCs) have become common engineering materials and are designed and manufactured lbr various applications including automotive components, sporting goods, aerospace parts. The growth in composite usage also came about because of increased awareness regarding product performance and increased competition in the global market. 13ut these MMCs are very difficult to machine due to abrasive nature of reinforcement. This abrasive nature of reinforcement results in higher cutting forces and accelerated tool wear. Therefore in this report an attempt has been made to investigate the machining characteristics of hybrid MMCs. In this experimental investigation, drilling experiments were conducted on Al/I O%SiC, Al/I O%SiC/l %Gr and Al/I O%SiC/3%Gr hybrid composites, with the help of 1-ISCo twist, lISCo step and HSCo TiN coated drills. All types of MMCs were fabricated using stir casting method. The efThct of variables like feed, cutting speed, drill type and %of graphite on the thrust force, surface finish and torque has been studied. Results indicate that small addition of graphite reduces the thrust force in all types of MMCs. The results show that the output variables are greatly influenced by the feed rather than cutting speed for all cutting conditions for all types of MMCs. Also the surface roughness values of graphitic MMCs were slightly more than Al/lO%SiC. The graphitic MMCs have better machinability than those reinforced with SiC alone.