Determining the emissivity at the tool-chip interface during S235JR steel turning

Temperature on the chip-tool interface is important parameters in the analysis and control of turning process. Due to the high shear and friction, energies dissipated during a machining operation the temperature in the primary and secondary shear zones are usually very high; hence, affect the shear deformation and tool wear. In a single point cutting, heat is generated at three different zones i.e. primary shear zone, chip tool interface and the tool-workpiece interface. The primary shear zone temperature affects the mechanical properties of the work piece – chip material and temperatures at tool-chip and tool-work piece interfaces influence tool wear at tool face and flank respectively. Total tool wear rate and crater wear on the rake face are strongly influenced by the temperature at chip-tool interface. Therefore, it is desirable to determine the temperatures of the tool and chip interface to analyse or control the process. To measure the temperature at the tool-chip interface many experimental methods have been developed over the past century. Since at the interface there is a moving contact between the tool and chip in this work, authors propose infrared method for temperature measuring. To assure possibly high accurate of noncontact temperature measurement there is a need to keep in mind several factors, including determining appropriate value of emissivity. In this work, authors present results of experimental determining emissivity value of tool-chip interface. As initial value, emissivity of polished steel was taken.