Wear behaviour on the radius portion of a die in deep-drawing: Identification, localisation and evolution of the surface damage

The tribology behaviour of the die radius, in the deep-drawing process, results from surface interactions between the metal sheet and the tool under contact pressure. Friction, degradation of the sheet, surface quality and tool wear are a result of this interaction. This article aims to study degradations of the radius portion of a die in the deep-drawing process. The study on an industrial press is complex, so we developed our own test facility, an experimental device, which represents a deep-drawing process-simulator. It allows friction between the metal sheet and a die radius. It can dissociate the diverse mechanical effects exerted on the die radius by enabling a study of the component conditions found in deep-drawing (effect of the blankholder, of the pulling forces, the sliding rate, etc.). An experimental study was conducted on a low-carbon steel sheet and a X160CrMoV12 steel die radius. It revealed that the die radius surface was degraded by ploughing and transfer mechanisms. The distribution of these degradations on the die radius was localised in two areas but varied in intensity depending on the exit angle between the sheet and the die radius. The die radius friction coefficient has been modelled with respect to the mechanical characteristics of the deep-drawing process-simulator. This model leads to a correlation between the friction coefficient and the degradation evolutions on the die radius.