Surface topography effects on galling of hot dip galvanized sheet metal

Abstract

Abstract. During manufacturing of automotive parts from hot dip galvanized sheet metal, surface asperities of the forming tools can cause breakage of small coating particles. Long and narrow scratches appear on the surface of the form part, a phenomenon known as part surface galling. Laboratory testing using a slider on sheet tests (SOST) are performed in order to investigate surface topography effects on galling. These experiments reveal the dominant effect of tool surface roughness on galling. The tool surface roughness has a large effect on the size of the detached coating particles and the distance before scratch occurrence. If the tool roughness is low enough, no surface scratch formation is observed for the investigated range of sheet surface roughness. At a high tool surface roughness scratches are observed at a very short sliding distance for all tested materials. At an intermediate tool surface roughness, the materials selected for this investigation show measurable differences but no clear trend could be identified.