A Study On Machining Mechanism Of AlSiC Composite Materials With The Brazed Diamond Wheel

AlSiC matrix composites has been known for its high specific strength and specific modulus, high wear resistance, high temperature resistance, high thermal conductivity. These excellent properties make AlSiC matrix composites widely application area in aerospace, automotive, electronics and military industry. Nevertheless, the combination of the high hardness of SiC particle and high ductility of the aluminium matrix can make the materials difficult to machine, especially for the composite with higher volume fraction of the SiC particles. Mono layer brazed diamond wheels have the advantages of high bonding strength, high mean protrusion height, etc. In this study AlSiC composites with 20% and 50% volume fraction of SiC particles was machined by by single grain brazed diamond tools and the monolayer brazed diamond wheels. The main research contents and relevant conclusions are as follow:(1) The contact length, dimension characteristics and three-dimensional morphology and the microstructure of scratching grooves on the AlSiC matrix composites with different volume friction of SiC are analyzed. The removal mechanism and surface integrity of the AlSiC composite is also investigaed. Meanwhile, the scratching forces of the single diamond tool on AlSiC is analyzed.. The results shows that the contact length of AlSiC composite with 20%SiC is longer than AlSiC composite with 50% SiC, and the ploughing effect of AlSiC composite with 20% SiC is stronger than that of 50% one. The scratching forces of AlSiC composite with 20% SiC is higher than that of 50% one. Meanwhile, plastic removal of Al, fracture, pushing and pulverization of SiC are the main form of material removal of AlSiC in the grinding.(2) Monolayer brazed diamond wheels are used to grind AlSiC matrix composites. The relationship between grinding forces and diamond grain size, volume friction of particles is investigated. The surface morphology with different volume friction of AlSiC composite and different kinds of tools are observed. In addition, chips morphology of the composite materials are analyzed. The grinding performance and wear forms of the diamond wheel is studied. The results shows that the grinding forces of AlSiC composite with 20% SiC is higher than that of 50% one, in addition, finer mesh size of diamond wheel obtains the lower grinding forces. Plastic removal is account for the grinding mechanism of AlSiC composite with 20%SiC, however, the more brittle removal mechanism is account for AlSiC with 50% SiC. The chip of AlSiC composite with 20% SiCis the curly form and semi-continuous type. But blocky and discontinuous chips were obtained when grinding AlSiC composite with 50% SiC.