Evaluation of Thrust Force and Surface Roughness in Drilling of Al-2219/B4C/Gr Metal Matrix Composites

Metal matrix composites (MMC) have been found to be useful in a number of engineering applications and particle reinforced aluminum MMCs have received considerable attention due to their excellent engineering properties like high strength to weight ratio, high toughness, high impact strength etc. But these materials are generally regarded as extremely difficult to machine, because of the abrasive characteristics of the reinforced particulates. This paper focuses on effect of cutting parameters on thrust force, surface roughness and burr height during drilling of MMCs. In the present work, discuss the influence of spindle speed and feed rate on drilling the Al-2219+8%B₄C (mono) composite and Al-2219+8%B₄C+3%Gr (hybrid) composite. The composites were fabricated using stir casting method. The drilling experiments were conducted by CNC machine with TiN coated HSS and carbide tools at various spindle speeds and feed rates. The thrust force, burr height and surface roughness of the drilled hole were investigated with attention paid to the effects of boron carbide and graphite particles composites. The experimental results show that the feed rate has more influence on thrust force and surface roughness. Hybrid composites exhibit lesser thrust force and discontinuous chips were produces when compared with mono composite during drilling process. It is due to the solid lubricant property of graphite which reduces the lesser thrust force, burr height and lower surface roughness. The holes surface finish was evaluated and very good results, exceeding standard values for drilling, were obtained with carbide tool at low feed and high speeds.