A Fracture Mechanics Approach to the Prediction of Tool Wear in Dry High-Speed Machining of Aluminum Cast Alloys—Part 1: Model Development

Abstract

The utilization of cast aluminum alloys in automotive industry continues to rise because of consumer demand for a future generation of vehicles that will offer excellent fuel efficiency and emissions reduction, without compromising safety, performance, or comfort. Unlike wrought aluminum alloys, the cutting speed for cast aluminum alloys is considerably restricted due to the detrimental effect of the alloy’s silicon constituencies on tool life. In the present study, a new wear model is developed for tool-life management and enhancement, in a high-speed machining environment. The fracture-mechanics-based model requires normal and tangential stresses, acting on the flank of the cutting tool, as input data. Analysis of the subsurface crack propagation in the cobalt binder of cemented carbide cutting tool material is performed using a finite element (FE) model of the tool-workpiece sliding contact. The real microstructure of cemented carbide is incorporated into the FE model, and elastic-plastic properties of cobalt, defined by continuum theory of crystal plasticity are introduced. The estimation of the crack propagation rate is then used to predict the wear rate of the cutting tool. The model allows the microstructural characteristics of the cutting tool and workpiece material, as well as the tool’s loading conditions to be taken into consideration. Analysis of the results indicates that the interaction between the alloy’s hard silicon particles and the surface of the cutting tool is most detrimental to tool life. The fatigue wear of the cutting tool is shown to be directly proportional to the silicon content of the alloy, silicon grain size, and to the tool’s loading conditions.

Cyber–Physical Systems for High-Performance Machining of Difficult to Cut Materials in I5.0 Era—A Review

“…The analytical calculation of ∆CTD can be extremely complicated. Further developments revealed that the ∆CTD can be determined from finite element modelling to calculate the resultant CTD from the crack tip sliding displacement ∆CTSD and the crack tip opening displacement ∆CTO, as represented in the following equation [126]:…”

“…An essential aspect of a cyber-physical machining system is to predict the tool life and adjust the cutting conditions to utilize the full potential of the tool while avoiding excessive wear rates. A wear model developed based on the finite element of crack propagation in the tool microstructure can determine the wear status more accurately, as presented in [121,126]. In this study, the flank face of the tool was partitioned based on the average size of the WC grains of the tool material, as shown in Figure 8a.…”

“…The state of tool wear has a significant impact on machining optimization objectives such as energy consumption and product quality [129]. Tool wear mechanisms can be attributed to mechanical [126], thermal [133], and chemical [134] aspects, making the wear phenomenon a complex modelling problem. Traditionally, direct tool wear evaluation techniques such as using a microscope, CCD (charged-coupled device) camera, or laser beam have been used to assess the status of tool wear.…”

High-Performance Machining System: Process Optimization for a Cyber-Physical System – a Review

“…The state of tool wear has a significant impact on machining optimization objectives such as energy consumption and product quality [56]. Tool wear mechanisms can be attributed to mechanical [88,89], thermal [90,91], and chemical [92,93], making the wear phenomenon a complex modelling problem. Traditionally, direct tool wear evaluation techniques such as using a microscope, CCD (charged-coupled device) camera, or laser beam have been used to assess the status of tool wear.…”

“…The mechanically activated wear can be simulated based on the finite element simulation of crack propagation in the tool material [88,89,293,294]. In order to model the temperature-activated wear mechanism, it is important to determine the temperature distribution at the interfaces of the tool-chip and tool-workpiece.…”