Coating effects on the galling behaviour of aluminium metal forming processes

This paper investigates the effect of coatings on the galling behaviour in metal forming processes. To investigate this phenomenon, pin-on-disc tests were conducted on the Anton Paar THT tribometer with discs manufactured from tool materials and pins manufactured from aluminium to represent the workpiece. Three different coating conditions were tested: uncoated contact, AlCrN and CrN coatings, at three different temperatures: room temperature, 300 degrees C and 450 degrees C. The investigation indicated that advanced coatings have a significant effect on coefficient of friction and galling behaviour, while these effects may rely on the selection of substrate and forming temperature. In general, compared with uncoated contact conditions, lower friction coefficients were generated with coated tools. In addition, the selection of aluminium grade for the pin affected friction coefficient, with AA6082 generating higher friction coefficients compared to AA7075.