Machining of metal matrix composites and attainable surface integrity

在过去的几十年里，金属基复合材料(MMC)在包括汽车和航空航天在内的几个制造业领域受到了极大的关注，这些行业是加拿大经济的主要组成部分。与未增强的合金相比，MMC具有更好的物理和机械性能。因此，在许多工程应用中，它们被认为是传统合金的替代材料。其独特的物理性能给了它们巨大的潜力，然而，要想让MMC广泛地取代整体材料，MMC面临着挑战。在机械加工过程中，韧性基体中的磨料强化会导致严重的刀具磨损和过早的刀具失效。虽然已经努力通过铸造或热锻造来生产MMCs，但所得到的近净形状的产品仍需加工成所设计的形状和尺寸。钢筋颗粒的开裂和剥离也是机械加工表面的重要损伤模式，亚表面损伤评估对机械加工构件的疲劳损伤至关重要，特别是在航空航天等关键应用中。已加工表面物理性能和加工残余应力的变化可归因于机械载荷和热载荷(产生的热)。克服这一挑战的一种方法是减少/消除刀具磨损的有害影响。以前用自推进旋转刀具加工其他难加工材料的成功经验使其成为在切割MMC时更好地控制刀具磨损和刀具寿命的良好候选者。

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.