A STUDY OF CUTTING PERFORMANCE IN TURNING PLAIN CARBON-STEEL USING TIN-COATED, TICN-COATED, AND UNCOATED CEMENTED CARBIDE TOOLS WITH CHAMFERED MAIN CUTTING EDGE

A special tool holder and its geometry was designed for this study. The tool holders, made of medium carbon steel, were milled and ground to various specifications. Tools of three kinds, i.e., TiN-coated, TiCN-coated and uncoated with chamfered main cutting edge (CMCE) were used in turning of carbon steel and pure aluminum to study the mechanism of secondary chip formation. According to the overall performance, the coated CMCE tools were better than the uncoated CMCE tools. In regard to the values of cutting forces and current consumption, the surface roughness of the work piece and the temperature of the tip surface, the levels of coated CMCE tools were all smaller than for the uncoated ones. The cutting force for the TiCN-coated CMCE tools was smaller than that of the TiN-coated ones. From the surface roughness of the work piece, the TiN-coated CMCE tools showed better results. From the color of the main chip and the hardness of the secondary chip, the temperature of the secondary chip was determined to be higher than that of the main chip. We postulate that CMCE tools may be transferring cutting heat more easily from the tip surface than the conventional tools.