Characterisation of tool coatings for press hardening

Hot sheet metal forming is gaining in importance in many fields, because of its capability to produce more complex components than possible with cold forming. Hot forming is also used to influence the final material properties with the hot forming of manganese-boron steels being a good example. One of the major challenges in hot forming is the tribological conditions between the tool and sheet material at the required high temperatures. This article will discuss the influence of different tool material coatings, ranging from PVD to mechanically bonded ceramic coatings, on the tribological conditions during forming. It will also shed light on how these coatings influence the heat transfer between the component´s material and the tool material. Another aspect which will be presented is how the different materials such as titanium, magnesium, 22MnB5 and aluminium behave under typical tribological conditions found in hot forming.