The study shows that considerable reserves still exist for increasing the service times of CrN-coated  dies for Al hot extrusion. The main reasons for the decreased service times are revealed and explained regarding  the selected CrN-coated die for hot extrusion, i.e. why the service time of the coated-die is not in accordance with  the wear resistance of the CrN-coating. The shaping of the bearing surface and presence of the scratches, size and  amount of nonmetalic inclusions in the die steel, nodular defects in the CrN-coating, as well as thicknesses uniformity  of CrN-coatings along the bearing surface, are relevant influential parameters.

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