An investigative study of the interface heat transfer coefficient for finite element modelling of high-speed machining

Abstract

This paper is concerned with the development of an experimental set-up and finite element (FE) modelling of dry sliding of metals to estimate the interface heat transfer coefficient. Heat transfer between the chip, the tool, and the environment during the metal-machining process has an impact on the temperatures and on the wear mechanisms, and hence on the tool life and on the accuracy of the machined component. For modelling of the metal-machining process, the interface heat transfer coefficient is an important input parameter to quantify the transfer of heat between the chip and the tool and to predict the temperature distribution accurately within the cutting tool. In previous studies involving FE analysis of the metal-machining process, the heat transfer coefficient has been assumed to be between 10 kW/m2 °C and 100 000 kW/m2 °C, with a background from metal-forming processes (especially forging). Based on the operating characteristics, metal-forming and metal-machining processes are different in nature. Hence there was a need to develop a procedure close to the metal-machining process, to estimate this parameter in order to increase the reliability of FE models. To this end, an experimental set-up was developed in which an uncoated cemented carbide pin was rubbed against a steel workpiece while the later was rotated at speeds similar to the cutting tests. This modified pin-on-disc set-up was equipped with temperature and force-monitoring equipment. An FE model was constructed for heat generation and frictional contact. The experimental and modelling results of the dry sliding process yield the interface heat transfer coefficient for a range of rubbing speeds.