A New High Speed Friction Test for Extrusion Processes

Abstract

A new axial friction set up for high speed friction was successfully developed and tested at the Extrusion Research and Development Center of TU Berlin. The friction behavior between the Aluminium alloy EN-AW 6060 and the hot-working steel 1.2344 at 300 °C and 400 °C was studied. The experiments were carried out with a relative friction speed from 0.1 to 50 mm/s, and a normalized contact/normal pressure of σn/kf ~ 0 and 1.5. The friction stress curves were depicted and compared with the Tresca friction model. A similar tendency between them was found, however all the theoretical results were around 15 and 30 % higher than the experimental results. In general, higher friction forces were found at 300 °C. Moreover, the effect of normal stress on the friction stress could be studied. By increasing the normalized normal stress from 0 to 1.5 kf the friction stress increases around 30 % at 300 °C and 10 % at 400 °C. A strong adhesion effect was observed especially at 400 °C, which represents around the 90 % of the total friction stress. The friction results can be reproduced using a friction factor of m= 0.85 at 300 °C and m= 0.7 at 400 °C.