Study On Precision Drilling And Milling Processing For High Volume Fraction Aluminium Matrix Composites

Being one of the advanced composite materials, silicon particle reinforced aluminium matrix composites (SiCp/Al) have a unique combination of physical and mechanical properties such as high specific strength and stiffness and excellent impact resistance, which have now been widely used in the areas of aerospace and military applications. Machining operation is absolutely necessary in manufacturing process of composites structure. However, owing to the different properties between aluminium alloy substrate and SiC particles reinforced body, composite is one of the representative difficult-to-cut materials. Machining technology of SiC particle reinforced aluminium matrix composites has a great influence on the performance and service life of the composite structure. It proved to be the key factor to dominate the development and application of the material.In this paper, the study was carried out on SiCp/Al composites. Aiming at the problem of poor machinability in conventional machining of SiCp/Al composites, the formation reason for machining damage was analyzed. By studying the way to minimise damage in machining of SiCp/Al composites, machining theory of grind-drilling SiCp/Al composites and evaluation of hole edge collapse defects in SiCp/Al composites were proposed. The main contents and academic achievements in this investigation are shown in the following.(1) The hole edge collapse defects in drilling45%-65%volume ratio SiCp/Al composites were observed and statistically summarized, then the model of edge collapse was established and a geometric method has been presented to evaluate edge collapse. The result shows that the evaluation of method is objective to evaluate the edge collapse defect under different parameters in drilling SiCp/Al composites, and it can guide to optimize the process parameters.(2) Based on the situation that traditional carbide twist drill is easily to wear and even break in drilling SiCp/Al composite materials. In order to improve the drilling quality, machining theory of grind-drilling SiCp/Al composites was proposed. Parameters experiment by diamond abrasive grind-drilling tool was carried out to prove the machining theory.(3) Base on the SiCp/Al composites poor milling surface quality and high roughness by carbide tool. High precision milling technology by PCD was proposed. Experiment of drilling45%volume fraction SiCp/Al composites by PCD was carried out. And it can effectively reduce surface roughness value and obtain good surface quality under reasonable parameters.