Reliability of PVD-coated single-layer TiAlN carbide tool during turning of hardened AISI 4340 alloy steel

Abstract

Reliability of a cutting tool in terms of tool wear is of foremost importance in metal cutting owing to its direct impact on the surface quality of the machined surface, and its dimensional accuracy, and consequently, on the economics of machining operations. With this view, in the present work, reliability of single layer PVD-coated TiAlN carbide tool is assessed during turning of hardened AISI 4340 steel (35 HRC) at various cutting conditions. Dry cutting tests were carried out with cutting speeds of 142, 265, 345 and 487 m/min and feed and depth of cut values of 0.125 mm/rev and 0.8 mm, respectively. Flank wear and its growth was monitored at regular intervals of length of cut using a digital microscope with a maximum magnification of 230X. Reliability of cutting tool obtained at different cutting conditions is compared with a view to understand the progression of tool wear and wear mechanisms at different stages of tool life. Environmental scanning electron microscope (ESEM) with energy dispersive X-ray spectroscopy (EDAX) system was used to understand tool wear and wear mechanisms. It has been observed that a better reliability of a PVD- coated tool could be obtained by limiting the cutting speed 200-250 m/min as at higher cutting speeds lower cutting tool reliability resulted due to the weakening of the cutting edge by an accelerated crater wear rate.