WC inserts coated with TïN/TiAlN nanolayers: Mechanical evaluations during machining

Abstract

The physics evaluation of the coating inserts don’t give enough information about the results during the machining, the present paper presents a study of tungsten carbide inserts (WC), coated with multinanolayers of [TiN/TiAlN]n. The coating has a 4µm thickness and contains 200 or 300 layers. This has been obtained by using a Plasma Assited Physical Vapor technique (PVD). The results obtained during the experiments were compared with the monolayer coated inserts (TiCN- Al2O3 -TiN) produced in an industrial way. This technology enables layers thickness to be in the order of nanometers.
Tool life, temperature, roughness of the surface on the workpiece and in the inserts, and the print of contact were the variables measured during experimentation. The tests were carried out using AISI 4340 steel workpiece with 50 HRc and using High Speeds Cutting (HSC).
The values of temperature that measured the tools studied were lower than usual; the temperature decrease was of 520°C for the inserts coated with 300 layers and of 770°C for the inserts coated with 200 layers.
The wear test results, demonstrated that the coated inserts with 200 and 300 layers, reached tool life bigger in 44% and 57% respectively, compared with the values obtained (7600m.) by inserts of TINAL.