Investigation on tapping of al6061-sic metal matrix composite with HSS taps

The present study deals with tapping of Al6061/SiC metal matrix composite. Stir casting technique was used for the fabrication of composite. Castings were produced by varying weight percentage of SiC (5, 7.5 and 10 wt. %) of 23 μm size in Al6061. The fabricated specimens were characterized for their hardness and tensile strength. It was found that hardness increases by the addition of SiC. Images from Scanning Electron Microscope (SEM) and metallurgical microscope showed the fair distribution of reinforcement. Due to the presence of SiC reinforcement that is highly abrasive in nature makes machining difficult and produces high rate of tool wear. After drilling, tapping experiments were conducted for the machinability study of Al6061/SiC metal matrix composite by using M8 HSS machine tap. Tapping operation was performed under dry condition with different cutting speed (12, 14 and 16 m/min) and constant feed rate equal to the pitch of thread. Torque required for tapping was measured using strain gauge based two-component cutting tool dynamometer. Microstructure and surface morphology of thread surfaces was analyzed using Metallurgical Microscope and Scanning Electron Microscope (SEM) respectively. Estimation of progressive flank wear of machine taps was undertaken using profile projector. The performance of HSS machine taps was evaluated in terms of tapping torque, tool flank wear and surface characteristics of thread surfaces.