Experimental determination of the tool–chip thermal contact conductance in machining process

Abstract

Tool–chip contact is still a challenging issue that affects the accuracy in numerical analysis of machining processes. The tool–chip contact phenomenon can be considered from two points of view: mechanical and thermal contacts. Although, there is extensive published literature which addresses the friction modeling of the tool–chip interface, the thermal aspects of the tool–chip contact have not been investigated adequately. In this paper, an experimental procedure is adopted to determine the average thermal contact conductance (TCC) in the tool–chip contact area in the machining operation. The tool temperature and the heat flux in tool–chip contact area were determined by inverse thermal solution. Infra-red thermography was also used to measure the average chip temperature near the tool–chip interface. To investigate the effects of the work piece material properties on the tool–chip TCC, AISI 1045, AISI 304 and Titanium materials were considered in the machining experiments. Effects of the cutting parameters such as cutting velocity and feed rate on TCC were also investigated. Evaluating the tool–chip thermal contact conductance for the tested materials shows that TCC is directly proportional to the thermal conductivity and inversely proportional to the mechanical strength of the work piece. The thermal contact conductance presented in this paper can be used in the future numerical and analytical modeling of the machining process to achieve more accurate simulations of the temperature distribution in the cutting zone and better understanding of the tool–chip contact phenomena.