Carbon based tool coatings as an approach for environmentally friendly metal forming processes

The deep-drawing of austenitic stainless steel AISI 304 provides a considerable challenge for production engineers. A major problem in such processes is adhesive tool wear which is often prevented using chlorous mineral oils. The aim of this work was to replace these hazardous lubricants with biodegradable, rape oil based fluids. For that purpose a modified triglyceride named HIGTO(I) is used in combination with a graded zirconium carbide (ZrCg) physical vapour deposition (PVD) tool coating chosen because of their good performance in previous studies. The results from deep-drawing tests with uncoated dies show that HIGTO(I) itself is not able to replace chlorous deep-drawing oils. But in combination with HIGTO(I) as a lubricant and ZrCg as tool coating deep-drawing forces are reduced and adhesive tool wear is prevented. This combination even exceeds the performance of chlorous deep-drawing oils. The wear effects, which appeared in different tests, could be explained by an analysis of tool loads and process temperatures, calculated using FE-simulations.