Correlation of the impact resistance of variously doped CrAlN PVD coatings with their cutting performance in milling aerospace alloys

A novel methodology based on analytical and experimental test methods for predicting coated tool efficiency in milling Inconel 718 and Ti6Al4V by coated cemented carbide inserts is introduced. The applied coatings were CrAlN films, containing alternatively Zr or Y dopants. The stress-strain curves and the fatigue critical loads of the applied coatings were determined at various temperatures by nanoindentations and impact tests respectively, employing various FEM-supported procedures for results evaluation. The milling investigations were conducted at various cutting speeds and feedrates. An insight of the developed stress and temperature fields in the cutting wedge region was obtained by force measurements and calculations, based on FEM-simulations of the milling process. These results facilitated the explanation of the coated inserts' cutting performance at various conditions. A sufficient correlation of the coatings' impact resistance at various temperatures with their cutting performance at corresponding cutting speeds was revealed.