Reduction of adhesive wear in the aluminium sheet forming process
In the automotive industry, aluminium sheets are increasingly used to reduce the weight of the automotive bodies. A problem that occurs during the forming process is the tendency of aluminium sheets to cause adhesive wear. This has an adverse effect on the quality of the formed parts and the stability of the process. Moreover, production downtimes and reparations result in high costs.
The aim of this project is to gain insight into wear mechanisms of aluminium sheet forming processes. More specifically, the influence of local temperature peaks on adhesive wear will be analysed. Furthermore, concepts with which adhesive wear can be reduced and wear behaviour can be improved will be developed.
First, a defined temperature is set in the forming zone by applying specific heat inputs. This depicts the correlation between adhesive wear and temperature. Furthermore, the characteristics of the tribological system are varied systematically so as to identify the main parameters which influence adhesive wear. This information will be used to develop guidelines to reduce adhesive wear.
It was proven that there is a correlation between the temperature in the forming zone and the amount of adhesive wear. In the case of lubricant application, it was shown that the lubricant properties change as well. Due to the lower viscosity at higher temperatures, the lubricant film breaks up and initiates the mechanism of adhesive wear.
Adhesive wear occurs at different places in the forming zone. Here, a correlation between the contact normal stresses, which were calculated with the aid of finite element analysis, could be demonstrated. When using GGG70L as tool material, adhesive wear begins in the local areas of surface defects due to the spherical graphite.