PVD coatings of cermet inserts for milling applications

The present paper deals with the influence of some PVD coatings on the performance of a cermet tool when milling blocks of a normalised carbon steel AISI-SAE 1045. Two monolayers (thickness congruent to 3.5 mu m), TIN, and Ti2N, and three multilayers (thickness 6-7 mu m), TiCN+TiCN, TiCN+Ti2N and TiN+TiCN, obtained by a cathodic are technique were deposited on a commercial cermet insert of ISO type SPKN 1203 ED-TR. Evolution of flank wear VBB vs. cutting time was observed during dry face milling tests performed on a vertical CNC machine tool. The cutting performance of the uncoated and coated inserts are presented and compared in terms of tool life obtained until reaching a threshold on mean flank wear VBB = 0.20 mm. The relevant experimental results indicate that the influence of coatings is not always positive: variations of tool life obtained by use of coatings range from a decrement of congruent to 21% (Ti2N coating) to an increment of congruent to 7% (TiN+TiCN) with respect to the uncoated insert.