Investigation of Ti and Cr based PVD coatings deposited onto HSS Co 5 twist drills

This study investigates the properties and cutting performance of thin TiN, TiAlN, CrAlN and KTRN coatings applied by two PVD techniques. PVD techniques ARC and SARC (it denotes the arc method by STATON company, Slovakia – deposited with smaller microdrops) were used for the deposition of thin coatings onto twist drills prepared by powder metallurgy. Conventional types of coatings – monolayers TiN, TiAlN, CrAlN and advanced type of the coating – monolayer KTRN (denoted by producer – STATON company Slovakia) on the basis of Ti and Al deposited with smaller drops on the surface – were analyzed by standard techniques for surface status and quality assessment – coating thickness, chemical composition by EDX analysis, adhesion, hardness, roughness and tribological properties at room temperature. Durability testing of the twist drills was carried out according to the standard ISO 3685-1999. CrAlN and TiAlN monolayers achieved lower roughness when compared to monolayer TiN and advanced type of the monolayer KTRN. TiAlN and KTRN coatings which leads to the achievement of higher hardness and better coating quality. The microhardness values were ∼35 GPa. The results showed two to four times lower flank wear VB of the evaluated drills with TiAlN and KTRN coatings in comparison with equivalent uncoated material of the drill. The deposited TiAlN and KTRN coatings contributed to the improvement of their durability.