Recently, due to the increasing amount of aluminum machined in the automobile industry, there has arisen a corresponding need for tools to perform efficient and effective aluminum processing. For the machining of aluminum alloy that contains a large amount of silicon, highly wear-resistant cutting tools such as diamond coated ones are needed. Because high silicon aluminum alloy contains silicon particles dispersed in the matrix of aluminum, which quickly wear the tools. However, diamond coatings on cutting edges are easily broken off by the mechanical collision against the particles. Under anew concept of reducing the stress in diamond coatings on cutting edges, we tried to optimize the construction of coated drills by changing the shape of cutting edges and coating thickness. Shape of thinning and helix angle were selected as the parameters to optimize the shape of drills. The drills with negative angel of thinning and 20 degree helix angle showed the best performance including durability. By putting together the results above, the diamond-coated drills with optimized structure were newly developed. Their performance appeared to be satisfactory in cutting high silicon aluminum alloy from 12 to 23% silicon content.
