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TC21 alloy is a new alpha–beta damage tolerance titanium alloy with high strength and high toughness. Little work has been done in the field of machinability analysis since this alloy was developed. The cutting forces and tool wear in high-speed milling of TC21 alloy with physical vapor deposition ((Ti, Al)N-TiN)-coated carbide tools under different cutting conditions were investigated in this article. The results showed that the cutting force component Fx was more dominant of the three components, and the cutting forces presented an increasing trend with the tool wear progress, which in turn deteriorated the cutting condition and accelerated the tool failure progress. The major tool wear modes in high-speed side-milling TC21 alloy with coated carbide were adhesion and chipping on the rake face along with chipping and transverse crack on the flank face. Moreover, there was obvious nose depression from both the rake face and the flank face. Chipping along the flank and rake faces was identified as the main factor responsible for the failure of the coated carbide tools during the milling of titanium alloy TC21.

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This article presents the development of a three-dimensional finite element model to simulate the high-speed end milling of Ti-6Al-4V titanium alloy based on the commercial finite element package Abaqus/Explicit. The Johnson–Cook material constitutive model was employed to model the flow stress behavior of the workpiece. Zorev’s friction model was used to determine the frictional behavior of the tool–chip interface, and Johnson–Cook shear failure criterion was used to realize chip separation. Based on the three-dimensional finite element model, cutting forces in three directions were predicted under different cutting conditions, and chip evolution and morphologies of different cutting parameters were also analyzed. Corresponding high-speed end milling tests were conducted, and cutting forces were measured using a piezoelectric dynamometer in order to validate the finite element model. The simulation results demonstrate an acceptable agreement with experimental results in both the chip morphologies and cutting forces in the range of cutting speed and feed rates considered.

This study makes a comparison between whisker-reinforced alumina and SiAlON ceramic tools in high-speed face milling of Inconel 718. A series of tests have been conducted, and the cutting forces, tool wear morphologies and tool failure mechanisms are discussed with regard to a wide range of cutting speeds (500-3000 m/min). Results show that the resultant cutting force of SiAlON ceramic tool KY1540 is much bigger than that of whisker-reinforced alumina ceramic tool KY4300 at the same cutting condition. For both kinds of tools, under relatively lower cutting speed, nose notch wear is the predominant failure mode affecting the tool life, while further increase in the cutting speed, notch wear at the depth of cut becomes the determining factor. KY1540 shows a better notch wear and thermal shock resistance than KY4300. The tool failure mechanisms involve notching, microcracks, chipping, flaking, adhesion and oxidation wear. Better surface quality can be got using KY4300 ceramic tools.

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