Cold Forging with Lubricated Tools

Abstract

Cold forging processes require high-capability tribological systems in order to ensure sound forming results. Due to a rising ecological awareness, alternatives to the established and reliable conversion coatings are necessary. Single bath systems like polymers and salt wax coatings with integrated lubrication appear to be the most promising approach to prevent galling. For an optimization and investigation of the tribological system a definition of the tribological loads is necessary. However, only insufficient values are available in literature. Especially, long sliding distances, which occur in multistage operations, can cause a breakdown of the lubricant. Therefore, approaches are necessary to enable long sliding distances. This paper presents the results obtained with a cold forging tribometer, the Sliding Compression Test, which reveal the high impact of remaining lubricant on the friction coefficient. Also, tests with prelubricated tools show the ability to reduce the friction and the results of investigations with rough tool surfaces are presented.