Nano-scale multilayered composite coatings for cutting tools operating under heavy cutting conditions

The aim of this work was to create a methodology for the development of wear-resistant coatings. These coatings were deposited on the working surfaces of carbide inserts which were used for rough re-profile machining of railway wheels-sets. The coatings were formed using a filtered cathodic vacuum arc deposition (FCVAD). An investigation into the effect of the FCVAD process parameters on the composition and properties of the coatings was undertaken. The experimental work replicated industrial application conditions in terms of cutting speed (4080 m/min), feed rates (0.8-1.2 mm/rev) and depth of cuts (4.0-8.0 mm). An increased tool life was achieved using carbide inserts with nanostructured multilayer composite coatings based on the Ti-TiN-TiAlCrN compound. The paper presents the results of carbide inserts with newly developed coatings for heavy duty machining of railway wheel-sets. The main coatings parameters i.e. microhardness, thickness, strength of adhesion of "coating-substrate" and surface morphology were studied. The nano-scale grain structure and thickness of sublayers for each coating component allowed achieving a balanced wear of rake and flank surfaces without micro/macro chipping of contact areas and cutting edge of the inserts. The results presented here show that the cutting tool life of the inserts with the new wear-resistance coatings exceeded commercial coated tools by a factor of more than two. (C) 2014 Elsevier B.V.