Machining of metal matrix composites and attainable surface integrity

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During the past decades, Metal Matrix Composites (MMC) have received considerable interest in several manufacturing sectors including automotive and aerospace industries which represent a major sector of the Canadian economy. MMC possess superior physical and mechanical properties compared to nonreinforced alloys. Therefore they are being considered as a replacement material for the conventional alloys in many engineering applications. Their unique physical properties gave them a great potential, however, MMC faces challenges in order to have a wide spread MMCs substitution for monolithic materials. The presence of abrasive reinforcements in the ductile matrix causes severe tool wear and premature tool failure during machining operation. Although efforts have been made to produce MMCs by casting, or hot forging, the resulted near net-shape products still have to be machined into the designed shape and dimension. Cracking and debonding of the reinforcement particles are the significant damage modes of machined surface also, subsurface damage assessment is critical for machined components subjected to fatigue, especially in critical application such as aerospace. The changes in the machined surface physical properties and machining induced residual stresses are attributed to both mechanical as well as thermal load (heat generated). One way to overcome this challenge is by reducing/eliminating the harmful effect of tool wear. The previous successful work of machining other difficult to cut materials with self propelled rotary tools has made it a good candidate for better control of tool wear and tool life when cutting MMC.