Identification of a friction model for the bearing channel of hot aluminium extrusion dies by using ball-on-disc tests

A physically-based friction model is developed based on the ball-on-disc test results. The model is verified by using double action extrusion tests. Good agreements between the FE predictions and experiments have been obtained, in terms of the extrudate length and steady-state extrusion load, indicating that ball-on-disc test is an effect way of characterizing the friction for the bearing channel of hot extrusion dies. The nature of friction in the bearing channel can be summarized as a pressure dependant process: formation of isolated adhesive junctions, adhesive junctions growth and coalescence of adhesive junctions.