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The focus of this experimental study is to optimize the cutting parameters using eight cutting tools made from two different materials (Tool steel D3 and medium carbon steel C45).The medium carbon steel C45 has been chosen, because it is available and cheap material and its hardness can be raised by heat treatment. The tool steel D3 has outstanding resistance to deformation, distortion, and shrinkage in heat treatment. It is one of the hardest tool steels and retains a keen edge longer than tools made from other carbon steels. D3 has superior resistance to wear and abrasion imparted by a rich complex of hard, uniformly dispersed chromium carbides in the matrix. In this study we used heat treatment to get the desirable hardness, then many operations were conducted on the tools like milling, wire cut etc to make cutting tool geometries. The cutting tool geometries depended on the work piece material, in this study two types of work piece materials (austenitic stainless steel 304 and aluminum alloy 7075) have been used. In this work, also external turning tests was performed. All of the turning tests were performed under cooling conditions on CNC lath machine. The quality of surface finish is an important requirement for many turned work pieces. Thus, the choice of optimized cutting parameters is very important for controlling the required surface roughness (Ra). In this study, 3 parameters have been investigated. These parameters are cutting speed, depth of cut, feed rate. In addition, the surface roughness was selected from two types of work pieces austenitic stainless steel 304 and aluminum alloy 7075. In turning austenitic stainless steel 304 the cutting speed was (256 rpm, 286 rpm, 318 rpm ), feed rate (0.2mm/rev, 0.25mm/rev, 0.3mm/rev ) and depth of cut (0.5mm, 1.0mm, 1.5mm). also interning aluminum alloy 7075 the cutting speed was (500 lpm, 700 rpm, 900 rpm ), feed rate (0.2mm/rev, 025mm/rev, 0.3mm/rev) and depth of cut(0.5mm, 1.0mm, 1.5mm). Taguchi design was used, three levels of cutting speed, three levels of feed and three levels of depth of cut. The standard orthogonal array (1.9) has been selected in order to perform the matrix. Nine experiments were performed each experiment producing a test part which was tested for average surface roughness (Ra jim) and S/N ratios was calculated also full factorial design was used to find the average surface roughness Ra |iim value.
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