The mechanical properties of Ti-6Al-4V alloy are sensitive to strain rate and temperature load. The finite element simulation results of high-speed machining Ti-6Al-4V alloy depend on the accurate description of dynamic deformation. However, it is hard to describe the flow stress behavior in current constitutive models in a complex high-speed machining process for Ti-6Al-4V alloy. In this paper, the stress-strain curves of Ti-6Al-4V alloy under the wide ranges of strain rate and temperature are obtained by high-velocity uniaxial impact tests. The apparent coupling between temperature and strain is observed, which proves that the temperature is dependent on a hardening effect for Ti-6Al-4V alloy. A function describing the coupling between temperature and strain is then introduced into the modification for the original Johnson-Cook (JC) constitutive model. The maximum deviation between the predicted data from using the proposed modified JC constitutive model and experimental data is reduced from 10.43% to 4.19%. It can be concluded that the modified JC constitutive model is more suitable to describe the temperature-dependent hardening effect, which provides strong support for accurate finite element simulation of high-speed machining Ti-6Al-4V alloy.

This paper presents a review of recent advances in modeling and simulation of conventional metal machining processes, which continue to dominate a significant part of all machining processes, and in recent years, the need for predictive models for machining processes has grown in importance in the digital manufacturing age. Significant advances have been made in modeling the mechanics of cutting in conventional machining, driven by industrial need and enabled by rapid advances in computational power. The paper surveys the state-of-the-art in analytical and numerical modeling of conventional metal machining processes with a focus on their ability to predict useful performance attributes including chip geometry, forces, temperatures, tool wear, residual stress, and microstructure. Also included in the review is a discussion of the industrial use of modeling and simulation tools for conventional machining. Additionally, the practical applicability, implementation benefits, and methodological limitations of conventional machining process modeling have been examined. The paper concludes with a summary of future research directions in modeling and simulation of conventional metal machining processes.

Constitutive model is the most commonly used method to describe the material deformation behavior during machining process. This paper aims to investigate the material dynamic deformation during high speed machining of 7050-T7451 aluminum alloy with the aid of split Hopkinson pressure bar (SHPB) system and finite element (FE) analysis. First, the quasi static and dynamic compression behaviors of 7050-T7451 aluminum alloy are tested at different loading conditions with a wide range of strain rates (0.001 s, 4000 s, 6000 s, 8000 s, and 12,000 s) and temperatures (room temperature, 100 °C, 200 °C, 300 °C, and 400 °C). The influences of temperature on strain and strain rate hardening effects are revealed based on the flow stress behavior and microstructural alteration of tested specimens. Second, a modified Johnson–Cook (JCM) constitutive model is proposed considering the influence of temperature on strain and strain rate hardening. The prediction accuracies of Johnson–Cook (JC) and JCM constitutive models are compared, which indicates that the predicted flow stresses of JCM model agree better with the experimental results. Then the established JC and JCM models are embedded into FE analysis of orthogonal cutting for 7050-T7451 aluminum alloy. The reliabilities of two material models are evaluated with chip morphology and cutting force as assessment criteria. Finally, the material dynamic deformation behavior during high speed machining and compression test is compared. The research results can help to reveal the dynamic properties of 7050-T7451 aluminum alloy and provide mechanical foundation for FE analysis of high speed machining.

Material removal mechanism depends on the material property and machining parameters during machining process. This paper investigates the brittle removal mechanism of ductile materials with ultrahigh-speed machining. Based on the theory of stress wave propagation, the prediction model of critical cutting speed for ultrahigh-speed machining is proposed. The predicted critical cutting speed values are then validated with ultrahigh-speed machining experiments of Inconel 718 and 7050-T7451 aluminum alloy at the cutting speeds range from 50 m/min to 8000 m/min. The experimental results show that fragmented chips are produced above the critical cutting speed of 7000 m/min for Inconel 718 and 5000 m/min for 7050-T7451 aluminum alloy. The scanning electron microscopy (SEM) micrographs of fragmented chip fracture surface and finished workpiece surface are analyzed. Large amounts of cleavage steps and brittle cracks are observed on the fragmented chip surface. With the brittle cracks remains, the finished surface quality of ultrahigh-speed machining is worse than that of high-speed machining. The results show that the material property undergoes ductile-to-brittle transition so the brittle regime machining of ductile materials can be implemented with ultrahigh-speed machining. Taking both the machining efficiency and machining quality into account, the ultrahigh-speed machining is recommended to apply in rough machining or semifinishing, while high-speed machining is recommended to apply in finishing process. In the end, the definition and essence of ultrahigh-speed machining are concluded. This paper is enticing from both the engineering and the analytical perspectives aimed at revealing the mechanism of ultrahigh-speed machining and optimizing the machining parameters.

Eutectic aluminum-silicon alloys present high frictional coefficient and a high wear rate due to the low hardness under sliding friction conditions. In this paper, the eutectic aluminum-silicon alloy was textured firstly by micro-milling operations. Then, the micro-textured specimen was subjected to anodizing to fabricate alumina films. The surface topography, surface roughness, and bearing area ratio of micro-textured and anodizing micro-textured specimens were measured and characterized. For the anodizing micro-textured specimens, the surface roughness and superficial hardness increase compared with those for micro-textured ones. Tribological tests indicate that anodizing micro-textured samples present lower friction coefficient of 0.37 than that of flat samples of 0.43 under dry sliding conditions. However, they exhibit higher friction coefficient at 0.16 than that of flat samples of 0.13 under oil-lubricated conditions. The difference between the friction coefficient of anodizing micro-textured and flat samples under dry and oil-lubricated conditions is ascribed to the influence mechanism of surface roughness, bearing area ratio curves, and its relative parameters on the tribological performance of testing samples. The dry sliding friction coefficient has a positive correlation with bearing area ratio curves, while they present negative correlation with bearing area ratio curves under oil-lubricated conditions. The synergy method treated with micro-milling and anodizing provides an effective approach to enhance the dry sliding friction property of eutectic aluminum-silicon alloys.

Tool wear behavior is mainly influenced by cutting parameters for a given tool–workpiece pair and cutting process. Rapid tool wear increases production costs and deteriorates machining quality in manufacturing industries. Inconel 718 is prone to severe tool wear in the milling process due to its high strength under elevated temperature and being prone to work hardening. The effects of cutting speed and feed rate on the tool chipping mechanism and tool wear multi-patterns in face milling Inconel 718 with cemented carbide tools are investigated in this research. Firstly, the face milling experiments of Inconel 718 were conducted with various cutting speeds and feed rates. The experimental results show that the tool wear morphology, especially the tool edge chipping on the flank face, is changed with the cutting parameters. Secondly, the tool chipping mechanism in the milling process is discussed. The effects of cutting speed and feed rate on the chipping and wear patterns of cutting tools are clarified. Finally, the ANOVA analysis is conducted to verify the effects of cutting parameters on cutting force, tool life, and tool edge chipping. This work provides an experimental basis for process parameter optimization to alleviate cutting tool wear in machining processes.