Marco Teller

TL;DR: In this article, a compression-torsion-wear-test for metal forming is presented, which is able to scale the contact pressure to a multiple of the initial flow stress of soft aluminium.

Abstract: In cold extrusion of aluminum alloys adhesive wear can be prevented by an excessive lubrication of the process. While this causes additional process steps also environmental risks have to be addressed. Hence, dry metal forming, i.e. avoiding lubrication by means of coatings and topography modifications is highly desirable. In this paper first results concerning the behavior of tailored surfaces under dry metal forming conditions for pure aluminum are presented. Different surface treatments (laser polishing and Mo2BC coating) of the tool steel AISI H11 are tested in a compression-torsion-tribometer under conditions adapted from cold extrusion. Normal stresses six times higher than the initial yield stress of the tested workpiece material pure aluminum (AA1050-O) are applied. Furthermore, a strategy for the characterization of aluminum adhesions to the tool is introduced. The influences of different topographies and the presence of a coating on the loss of material due to adhesive wear are investigated.

TL;DR: In this article, a compression-torsion-tribometer is presented to scale the contact pressure to a multiple of the yield stress of the workpiece, which is characteristic for cold extrusion processes.

TL;DR: In this paper, the authors demonstrate that functionalizing tool steel die surfaces with an octadecylphosphonic acid molecular monolayer decreases friction during Al cold forming, and demonstrate that molecular functionalization leads to a 1.9-fold decrease in time-averaged torque during tribological compression-torsion wear tests.

TL;DR: In this article, the surface conditions of workpieces used for dry-metal forming experiments were analyzed using x-ray photo-electron spectroscopy, infrared and wetting experiments and the best cleaning results were obtained using a CO2-based approach.