Chip formation and its effects on cutting force, tool temperature, tool stress, and cutting edge wear in high- and ultra-high-speed milling

Abstract

In the present study, experimental tests and finite element simulation were conducted in order to investigate chip formation and its effects on cutting force, tool temperature, tool stress, and cutting edge wear in high-and ultra-highspeed (v=200∼2000 m/min) milling. It was found that the serration of chip became more and more obvious as the cutting speed increased. Most of the saw-tooth chip was separated at the cutting speed of 2000 m/min. During the formation process of the separated saw-tooth, the high temperature in the shear band had substantial effect on the initiation of the crack in the chip. When the cutting speed increased, the formation frequency of the saw-tooth increased with decreasing growth rate and the tool-chip contact length exhibited a decreasing trend. At each cutting speed used in the present work, the fluctuation frequency of cutting force, tool temperature, and tool stress was consistent with that of the saw-tooth formation. The saw-tooth formation which led to periodically changing cutting thickness had great effects on the cyclical fluctuations of the cutting force, tool temperature, and tool stress. When the cutting speed increased from 650 to 2000 m/min, the amplitude of the cutting force and tool temperature grew 116 and 93 %, respectively. The higher degree of chip serration at higher cutting speed resulted in the substantial change of the cutting thickness, leading to greater mechanical and thermal impact. The tool temperature had greater effect on the tool stress than the cutting force did when the cutting speed was relatively high. Due to the small tool-chip contact length at cutting speeds of 1550 and 2000 m/min, no obvious wear appeared on the tool rake face. Because of the higher average value and the higher amplitude of tool stress at the cutting speed of 2000 m/min, chipping emerged on the tool cutting edge. This phenomenon was not found on the cutting edge when the cutting speed was 1550 m/min.

Modeling and simulation of the high-speed milling of hardened steel SKD11 (62 HRC) based on SHPB technology

“…Shatla [9] conducted two-dimensional (2D) orthogonal slot milling experiments in conjunction with analytical-based OXCUT and Oxley's method to obtain flow stress data for the metal cutting of AISI P20 (30 HRC) and AISI H13 (46 HRC), and analyzed the tool chipping and surface integrity of a machined workpiece employing an FEM that fitted the J-C constitutive equation of stress data. Cui [10] employed the J-C constitutive equation of AISI H13 (46-47 HRC) and conducted experimental tests and finite simulation to investigate chip formation in high-and ultra-high-speed milling. He found that the serration of chips became increasingly obvious as the cutting speed increased, the formation frequency of a sawtooth increased with decreasing growth, and most of the sawtooth separated at a cutting speed of 2000 m/min.…”

Effects of Milling Methods and Cooling Strategies on Tool Wear, Chip Morphology and Surface Roughness in High Speed End-Milling of Inconel-718

“…Obikawa et al (2008) reported that by spraying small amount of lubrication, called micro-litre lubrication, on cutting zone using specially designed nozzle increased the tool life as compared to ordinary MQL spraying in machining of Inconel 718. Cui et al (2016) reported that the degree of chip serration increased and tool-chip contact length decreased with increase in cutting speed in high and ultra-high speed milling of AISI H13 hardened steel. They reported that the main tool wear pattern was flank wear.…”

Study of deformation zone effects of low, conventional, high and very high speed machining

“…An idea conveyed is that there are two cutting speeds at which the tool temperature will be the same and one of these is a much higher speed than the other. It is widely accepted that this was the start of the high speed machining (HSM) concept [1,4,5]. However, the appropriate cutting tool material was not available in that time.…”

“…The conclusions are contradicting but also supporting early theory. The topics involving high speed, temperature and wear are frequently reviewed [1,4,5]. The high speed machining was researched for turning and milling by various authors in conditions of either coated, uncoated cutting tools or dry and wet machining and different materials as the difficult to machined; hardened materials; stainless steel; alloys; composite materials etc.…”