Author name / Materials Today: Proceedings 00 (2018) 0000–00005material when reacted with atmospheric oxygen formed an Al2O3 oxide layer which resulting in protection of cutting edge from heat protection. However, when this thin coating layer wears out during machining by adhesion and abrasion wear mechanisms, the oxidation-dominated and diffusion wear mechanisms became active, resulting in rapid wearing of the substrate, and catastrophic failures at higher cutting speeds.
From the above discussion, it can be seen that by knowing reliability of a cutting tool and its behaviour, a suitable cutting condition can be selected with a view to assure the quality of the machined surface and overall economics of the machining operation. It can be seen that the reliability varying with cutting time generally confined to three distinct regions, namely, initial breakdown, uniform wear rate and rapid breakdown of the cutting edge as like the flank wear progression with cutting time.5.
ConclusionIn 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 with a view to understand the progression of tool wear and wear mechanisms at different stages of tool life. Flank wear and its growth was monitored at regular intervals of length of cut using a digital microscope with a maximum magnification of 230X. 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. It has been observed that the reliability varying with cutting time is generally confined to three distinct regions, namely, initial breakdown, uniform wear rate and rapid breakdown of the cutting edge as like the flank wear progression with cutting time.
Moreover, catastrophic tool failure observed at higher cutting speeds. It has been observed that by knowing reliability of a cutting tool and its behaviour, a suitable cutting condition could be selected with a view to assure the quality of the machined surface and overall economics of the machining operation.References1 H. Wiklund, Bayesian and regression approaches to on-line prediction of residual tool life. Quality and Reliability Engineering International 14/5 (1998) 303-309.2 V. Ilinykh, G.N.
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