Combined Surface Treatment of Forging Tools by Plasma Nitriding and PACVD

The lifetime of warm and hot forging tools is in comparison to other forming operations much lower because of the complex thermomechanical and tribological stress on the dies, punches and matrices. To enhance the tool life quantity the Fraunhofer-Institute for Production Technology and Automation (IPA) developed a combined nitriding and hard ceramic coating process in one cycle. TiN coatings are deposited on a basic plasma nitrided layer. Variations were made by the nitriding and process parameters. Getting better surface protection layers, improved tool life and resistance to abrasion were the objectives of these experiments. The usability of these coatings is tested under forging conditions using diferent forging dies and hot extrusion tools at the Institute for Metal Forming and Metal Forming Machine Tools (IFUM). Because of the positive test results the combined nitriding and coating process is not even in economical but also in ecological respect an interesting modification for in creasing tool life.