Measurements of thermal contact conductance

Abstract

During forging, the transfer of heat between the component, the tools and the environment has an impact on tool-life and the accuracy of the formed component. Consequently, the measurement of thermal contact conductance is of increasing interest to researchers and industrial engineers participating in the manufacture of high-precision components by plastic deformation. It is recognised that thermal contact conductance is a function of several parameters, the dominant ones being the type of contacting materials, the macro- and micro-geometry of the contacting surfaces, temperature, the interfacial pressure, the type of lubricant or contaminant and its thickness. A new steady-state method and measurement equipment are proposed in which the measurements are conducted on thin cylindrical specimens, which are retained under pressure between two tools. A clear advantage of this method is the ability to measure the thermal contact conductance under precisely controlled conditions. Due to the small aspect ratio of the specimen, the applied pressure may be of the same magnitude as that prevailing in industrial bulk-metal forming processes. In the present paper some experimental results on the dependence of h on the pressure and the specimen texture are presented.