Friction in aluminium extrusion—Part 1: A review of friction testing techniques for aluminium extrusion

In the aluminium extrusion process, the friction at the workpiece/tooling interface is a highly complex phenomenon, affected by local temperature, relative velocity, contact pressure, geometry and tooling surface roughness, etc. Despite of this understanding, general rules for the selection of friction testing techniques have not been established yet. This paper summarises the recent development of the friction testing techniques for aluminium extrusion processes and detailed comparisons of these techniques are presented. Of the existing friction testing techniques, the combination of extrusion friction tests and short sliding distance ball-on-disc tests is recommended.

► The recent development of friction testing techniques has been reviewed.
► The recent development of the friction models for aluminium extrusion has been reviewed.
► Short sliding distance ball-on-disc tests can be used for the determination of friction for the bearing channel region.
► Extrusion friction tests can be used for the determination of friction for the billet/container interface.
► Full sticking friction represents the interfacial contact between hot aluminium and die the best.