Literature agrees that thermal effects have a great influence on friction. However, the heat flows and the thermal behaviour of test rigs used to characterize friction coefficient are largely dependent on their architecture. As a consequence, some discrepancies can be noted between the frictional responses measured by different test benches. Therefore, a thermal model of a twin-disc machine has been developed using the thermal network methodology. This model allows thermal analyses of the traction tests performed with this twin-disc machine. The results reveal that the disc bulk temperature has a significant impact on friction coefficient. Some scuffing experiments are also studied thanks to this numerical model, and a thermal interpretation of classical scuffing criteria is proposed.