Experimental Investigation of Temperature Distribution in the Chips, Workpiece and Cutting Tool During Machining Operations

Abstract

High temperature values are encountered during machining processes and these high temperature values have negative influences on the tool, workpiece, chip formation mechanisms, the process efficiency and the quality of surface of the machined parts. These negative influences can be reduced drastically with the use of appropriate cutting tool with suitable depth of cut during machining operations. The studies of these thermal fields in machining are necessary and very important for the development of new technologies aiming to increase the tool lives and to reduce production costs. This work centers on measurement of temperatures in the chips, cutting tool and workpiece during turning and drilling operations using uncoated high-speed steel and coated cemented carbide cutting tools at different cutting speeds and depths of cut to ascertain the more suitable cutting tool and feed rate during machining operations. Although, the direct temperature measurement at the chip-tool interface are very complex, the turning experiments were performed on a lathe machine at varying turning speeds and depths of cut, while the drilling operation was performed on a drilling machine at different turning speeds and depths of cut. All the experiments were carried out at the mechanical Engineering workshop of Federal University of Technology, Owerri. The temperature values of chip, cutting tool and workpiece when working on brass, high-carbon steel and stainless steel were measured using digital thermocouples. The results obtained showed that uncoated high-speed steel cutting tool could not cut stainless steel and high-carbon steel at very high turning speed and depth of cut due to the excessive heat it generated at the contact area, and at very low cutting speed the temperature of the cutting tools were higher than the workpiece irrespective of the cutting tool till an increased cutting speed where temperature of workpiece became higher than the cutting tool. It is recommended that coated cemented carbide on hard materials be used during turning and drilling to ensure a negligible increase in temperature while machining, also monitor speed for required finishing and extended tool life.