Tool material experiences from pressing of heat exchanger plates

Wear in forming tools and contact problems between sheet-metal and tool-material are common problems in manufacturing industries and sheet-metal-parts production. In this paper recent tool material experiences are presented. Quantitative determination of wear has been performed using micro hardness indentions made on the tool surface prior to pressings and thereafter measured. Wear tests are performed with both model tools in a wear test press and in one case study. It is shown in this paper that: VANCRON shows equally good anti-galling properties as VANADIS 4 with TICRON treatment in model tools. VANCRON was successfully used in a production tool (case study) for 1,000,000 pressings without galling problems. The wear is small and production can continue further. VANADIS 4 with TICRON treatment in the same application is recoated before 1,000,000 parts. The method of using micro hardness indentions appears to be a promising way to quantitatively determine wear depths on tool surfaces. The studied wear depths are of magnitude 0-10 μm and the precision of the method is estimated to ± 0.05 μm. It is possible to follow the wear already in an early stage with the method of using micro hardness indentions both in model tools and in production tools. It is complex to measure wear with a test method outside the actual pressing operation and it is difficult to compare the results from different test methods due to the differences in how the wear is achieved. The method with special Wear Test Press WTP is a method with result very close to the wear appearing in an actual pressing operation of heat exchanger plates. Increased depth accelerates test procedure compared to a production tool.