This article presents the detailed discussions on fabrication of aluminum-silicon carbide (10% by weight of particles) and boron carbide (5% by weight of particles) hybrid metal matrix composites (Al/SiC/B4C - MMCs) using stir casting method. The cylindrical rods of diameter 65mm and length 200mm are fabricated and subsequently machined using medium duty lathe to study the machinability issues of hybrid MMC using polycrystalline diamond insert of 1600 grade. The optimum machining parameters have been identified by a composite desirability value obtained from desirability function analysis as the performance index, and significant contribution of parameters can then be determined by analysis of variance. Confirmation test is also conducted to validate the test result. Experimental results have shown that machining performance can be improved effectively through this approach. Results show at higher cutting speeds, good surface finish is obtained with faster tool wear. Percentage of error obtained between experimental value and predicted value is within the limit. Using the optimal parameters, tool wear analysis also studied for the duration of 30min. © 2012 Copyright Taylor and Francis Group, LLC.