Experimental simulation of tool/product interface during hot drawing

During hot drawing, work tools are subjected to severe constraints. Thus, tool wear is a main preoccupation for industrial engineers. For this reason, it is important to better understand the phenomena which occur at the interface between tool and sheet in this kind of process. That is why, a pin on disc tribometer for high temperature has been designed and achieved. Its originality consists in having an open contact on a continuously new disc surface. This machine permits the simulation of the contact at the tool/product interface during the hot drawing process.In this paper, this new tribometer is described. Then, a friction and wear comparative study of various tool materials is carried out at a temperature of 400 °C and with a pressure of 20 MPa. The classification of these materials is done according to the measurement of the friction coefficient and the wear characterization. Pins, which represent tools are: X153CrMoV12 steel samples uncoated and coated with TiAlN deposited by PVD process and nodular cast iron GJS 600 ones.Sheets made of steel and representing drawing products are: uncoated and coated samples by bimetallic alloy coating. The tribometer is able to classify and to evaluate the tribological performances of the different combinations of pins and sheets. Tests show that coatings reduce friction. However, they do not prevent adhesive wear of pins.