Effects of the Tool Lubrication in Cold Forging

Cold forging is an efficient process to produce workpieces in huge lots with superior properties. To further optimize these processes, the tribology must be improved. Therefore, many new lubricants exist, which can be used for moderate loads and single-stage operations. However, multistage operations are critical for adhesion and wear due to the high sliding distances. Thus, this paper presents the results from a cold forging tribometer and the Sliding Compression Test, which reveals the high impact of remaining lubricant on the tools to the friction coefficient. This remaining lubricant can decrease the friction coefficient. In addition to a conventional lubrication of the specimen, tests with lubricated tools have been conducted. These investigations have shown a further decrease in the coefficient of friction. Tests with lubricated rough tool surfaces helped to further optimize multistage cold forging operations since additional lubricant can be trapped on the tool surface. Finally, this paper presents an approach to avoid complex lubrication of the specimens by using lubrication of the tool.