The effect of inclusion composition on tool wear in hard part turning using PCBN cutting tools

Abstract

This work reports on hard part turning of carburizing steels using a PCBN cutting tool in fine machining. Emphasis is on the link between composition of the inclusions in work material and wear mechanisms of the cutting tool. A Ca-treated machinability improved 20NiCrMo steel was included together with three other carburizing steels with different inclusion characteristics. Machining tests were conducted to examine cutting tool life and its balance between excessive flank wear or crater wear. The wear mechanisms were examined using a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectrometer (EDS) and a secondary electron (SE) detector. The longest tool life was obtained when cutting the Ca-treated steel. The improved machinability is linked to the deposition of complex (Mn,Ca)S and (Ca,Al)(O,S) protective slag layers that form on the rake face of the cutting tool during machining. Cutting in this steel also resulted in a typical ridge formation in the tool edge crater. Transfer of workpiece material to the rake face crater is characteristic in hard part turning of steel with high cleanliness. This is suggested to be related to the lack of the sulphides that lubricate conventional machinability treated steels, and that the crater wear of low-sulphur steel is more pronounced than for steels with higher sulphur content.<p>QC 20150421</p

PCBN Performance in High Speed Finishing Turning of Inconel 718

“…The main wear mechanism was abrasion wear [17], causing crater wear resulting in final cutting edge failure. Similar wear mechanisms were observed by the authors in references [18,19] in high speed machining of hardened steel. W.Y.H.…”

Effect of Si in Workpiece Material on Tool Wear in Hard Turning

“…The cross-sections of the chips were prepared through embedding and polishing. Each test was conducted once, since previous work 7) with similar cutting tests shows the standard deviation in the test is expected to be small. The depth of cut of 0.1 mm was small against the nose radius of the tool of 1.2 mm.…”

“…5) Another study has revealed that ceramic binders are better than metal binders in terms of adhesive wear resistance. 6) Regarding the influence of workpiece material composition on tool life, Ånmark et al 7) reported that when Ca-treated hardened steel is cut, multiple protective oxide layers of (Mn, Ca)S and (Ca, Al)(O, S) are formed on the tool, resulting in improved tool life. In addition, in the case where the work material is other than hardened steel, some researchers have reported that when cast iron is cut using a CBN tool, high Si content in the workpiece increases tool wear because Si in the workpiece reacts with Al in the tool binder, which changes the binder into SiAlON with low high-temperature strength.…”

Effect of Selenium on the Machinability of As-hot Rolled and Heat Treated 4140 Steel

“…3,4) Therefore, the machinability of steel is dependent on the characteristics of the workpiece, the cutting tool, and the machining parameters. 5,6) Chinchanikar et al 7) investigated the machinability of AISI 4340 steel with different levels of hardness. For the harder workpiece, higher cutting force but a better surface finish was observed.…”