Surface roughness and microstructure analysis on drilling of titanium diboride in-situ aluminium metal matrix composite

Aluminium and its alloys are widely used for fabricating components are used in aircraft, automobile, defence and structural applications. Due to its light weight and high strength, it is applied in the various commercial purposes such as window, doors, construction member etc. However, machining of aluminium alloys using conventional machining methods is difficult. In this present investigation, an endeavour has been made to drill TiB2 in situ aluminium metal matrix composite alloy developed using stir casting method. During the casting two different salts namely K2TiF6 and KBF4 are added with matrix materials to form TiB2. The paper is studied the surface roughness (SR) of drilled TiB2 in situ aluminium metal matrix composite viz speed, feed rate and TiB2 addition. Empirical relationship is developed for SR in order to identify the dominating factors. The percentage contribution of SR is 96.35% that showed the empirical model is adequate. The normal probability plot showed the points of residuals are equally distributed over the straight line. The lack of fit value was 3.65 which is less than the standard point. Therefore, the SR model is satisfactory. SR increased with increasing of speed, feed rate and addition of TiB2. The removal of TiB2 particles causes small pits and voids due to the inclusion of reinforcement. The minimum SR was achieved at lowest speed (1260 rpm), feed rate (0.05 mm rev(-1)) and TiB2 addition (2%). As speed and feed increased, the surface hardness increased.