Increasing of Service Times of Nitrided and CrN Coated Dies for Al Hot Extrusion

AbstractThe main reasons for decreased service times of selected nitrided and CrN coated dies were revealed and explained. Results of analysis of wear on industrial dies were combined with results obtained in laboratory wear tests. The main influential parameters in this study refer to contact pressure, die design, length of bearing surface, quality of nitrided layer, surface preparation prior coating and maintenance. It was found that lower quality of nitrided layer in combination with short bearing surface and occurrence of increased contact pressure close to exit edge of bearing surface can considerably decrease die service time and that appropriate shaping of die contours around inlet and outlet areas of bearing surface has decisive influence on die service time