Analysis of a segmented die design approach to improving the performance of coated metal forming tools

Tool corrosion, abrasion, and adhesive wear can all have a significant adverse effect on production efficiency. They present a huge financial burden to manufacturing industry worldwide in terms of both material costs and equipment downtime. They also influence both the dimensional accuracy of the produced workpiece and its surface quality. An increase in effective tool life is thus one of the most important goals in metal and plastic forming. Applying a protective hard coating may increase tool life but frequently the tool design does not readily lend itself to coating. In this paper we show that segmented die designs can overcome this problem and also reduce the risk of tool fracture in operation. The example is taken of a segmented die used in hexagon nut cold forming, which will increase the tool life by eliminating high stresses at internal corners, allow a good surface finish and the deposition of hard coatings in an effective way. Coated segmented tooling gives good results in practical trials and provides extended tool life, enhanced productivity, and improved product quality.