Severe Tool Wear Research Articles

Chip morphology and cutting temperature of ADC12 aluminum alloy during high-speed milling

The ADC12 aluminum alloy is prone to severe tool wear and high cutting heat during high-speed milling because of its high hardness. This study analyzes the high-speed milling process from the perspective of different chip morphologies. The influence of cutting temperature on chip morphology was expounded. A two-dimensional orthogonal cutting model was established for finite element analysis (FEA) of high-speed milling of ADC12 aluminum alloy. A theoretical analysis model of cutting force and cutting temperature was proposed based on metal cutting theory. The variations in chip shape, cutting force, and cutting temperature with cutting speed increasing were analyzed via FEA. The results show that, with the increase in cutting speed, the chip morphology changes from continuous to serrated, and then back to continuous. The serrated chip is weakened and the cutting temperature is lowered when the speed is lower than 600 m·min−1 or higher than 1800 m·min−1. This study provides a reference for reducing cutting temperature, controlling chip morphology and improving cutting tool life.

Machinability of modified Inconel 713C using a WC TiAlN-coated tool

Abstract This paper investigates the machinability of Inconel 713C materials. Inconel 713C is difficult to cut and causes severe tool wear with built-up edge (BUE) formation and catastrophic fracture. The modified Inconel 713C materials are named as T1- and T2-grade alloys. T1- and T2-grade alloys were manufactured to increase the machinability by modifying the base Inconel 713C. The Inconel 713C, T1- and T2-grade alloys have been analyzed based on microstructure analysis and engineering data. T1 and T2 are typically less ductile than the base Inconel 713C. The machinability characteristics of these materials were studied using a turning machine, including the tool flank wear, wear mechanism, surface roughness, cutting temperature, chip formation, and cutting forces. A commercial tungsten carbide TiAlN-coated tool was used in the experiments. Abrasive wear mainly plays a role in the wear mechanism during the cutting of base Inconel 713C before either BUE formation or catastrophic fracture occurs. Erosion of the cutting edge occurs due to diffusion wear after abrasive wear when cutting both the T1- and T2-grade alloys. However, catastrophic fracture occurs regularly when cutting T2. Data on the surface roughness, cutting temperature, chip formation, and cutting forces are also provided. Based on the experimental results, T1 has the best machinability in term of lowest flank wear and cutting force.

Three-dimensional temperature prediction in cylindrical turning with large-chamfer insert based on a modified slip-line field approach

Chamfered inserts have found broader applications in metal cutting process especially in high-performance machining of hard-to-cut materials for their excellent edge resistance and cutting toughness. However, excessive heat generation and resulting high cutting temperature eventually cause severe tool wear and poor surface integrity, which simultaneously limits the optimal selection of machining parameters. In the present study, an analytical thermal–mechanical model is proposed for the prediction of the three-dimensional (3-D) temperature field in cylindrical turning with chamfered round insert based on a modified slip-line field approach. First, an innovative discretization method is introduced in a general 3-D coordinate system to provide a comprehensive demonstration of the irregular cutting geometry and heat generation zones. Then, a plasticity-theory-based slip-line field model is developed and employed to determine the intensities and geometries of every elementary heat sources in Primary Deformation Zones (PDZ), Secondary Deformation Zones (SDZ) and Dead Metal Zones (DMZ). At last, a 3-D analytical model is suggested to calculate the temperature increases caused by the entire heat sources and associated images. The maximum cutting temperature region predicted is found existing upon the chip-tool contact area rather than the tool edge. Moreover, the rationalities of cutting parameters employed are analyzed along with theoretical material removal rates and ensuing maximum cutting temperatures. The results indicate that the cutting conditions with large depth of cut and high cutting speed are more desirable than those with high feed rates. The proposed models are respectively verified through a series of 3-D Finite Element (FE) simulations and dry cutting experiments of Inconel 718 with chamfered round insert. Satisfactory agreement has been reached between the predictions and simulations as well as the measurements, which confirms the correctness and effectiveness of the presented analytical model.

A Review on the Finite Element Modeling of the Particle Reinforced Metal Matrix Composites in Cutting Process

Background:: Particle Reinforced Metal Matrix Composites (PRMMCs) are widely used because of the higher specific strength, better dimensional stability, lower thermal expansion coefficient, better wear and corrosion resistance. However, the existence of reinforcing particles makes it hard to machine. The main manifestations are as follows: severe tool wear, easy generation of debris tumors in processing, and many defects on the machined surface, etc. These seriously limit its wider application. The Finite Element Method (FEM) has been widely applied in the research of PRMMCs machining according to recent patents, which can improve the efficiency and reduce the cost of research. Therefore, it is necessary to carry out a deep research for the processing technology of PRMMCs. Methods:: In this paper, the latest research progress of finite element simulation of cutting PRMMCs was summarized. The key technologies of finite element simulation, including constitutive model, geometric model, friction model between chip and tool, fracture criterion and mesh generation, are comprehensively analyzed and summarized. The application in the specific processing methods was discussed, such as turning, milling, grinding, ultrasonic vibration grinding and drilling. The existing problems and development direction of the simulation of PRMMCs cutting are also given. Besides, a lot of patents on finite element simulation for PRMMCs machining were studied. Results:: Finite element model for the actual composition determines the accuracy of finite element simulation. Through the secondary development of finite element software, a more realistic finite element model of Particle reinforced metal matrix composites can be established. Conclusion:: Finite Element Method (FEM) provides a new approach for the study of mechanism of Particle reinforced metal matrix composites machining. Quantitative analysis and prediction of micro- details in cutting can be realized.

Analytical modeling of subsurface damage depth in machining of SiCp/Al composites

SiC particle reinforced aluminum matrix (SiCp/Al) composite has been one of the key light metal matrix composites, which is widely used in aerospace and electronics industries due to its excellent material properties. However, the abrasive particles within the materials easily lead to severe tool wear during machining, and the subsequent machining-induced subsurface damage (SSD) will significantly affect the fatigue properties of composite structures. In this paper, an analytical model considering the effects of reinforced particle, thermal-mechanical coupling, and tool wear is first proposed to predict the SSD depth during cutting of SiCp/Al composites. The two-body abrasion and three-body rolling mechanisms are introduced to describe the effects of the particles on the tool-chip interface friction. The mechanical stress and thermal stress induced by mechanical load and thermal load, respectively are simultaneously taken into account. Meanwhile, the tool wear is considered in modeling of friction characteristic of tool flank-workpiece. The SSD depth is evaluated as a measure of variation in microhardness along the depth normal to the cross-section of the machined surface. The correctness of the proposed model was validated by the orthogonal cutting experiments of SiCp/Al composites under different tool wear values and feed rates. A good agreement is found by comparing the predicted and experimental results, which proves that the proposed model can accurately predict the SSD depth with an error of 7.8% in average. Furthermore, the results indicate that even a new tool is used, the SSD depth can reach to hundred micros level during machining of SiCp/Al composites, which is significantly greater than homogeneous metal machining.

Experimental study of tool wear and its effects on cutting process of ultrasonic-assisted milling of Ti6Al4V

Ti6Al4V is usually considered difficult to machine, and therefore, it causes severe tool wear and shortens tool life while being machined during conventional milling, leading to loss of quality and accuracy of the machined parts. In this paper, the experiment of ultrasonic-assisted milling of Ti6Al4V was conducted to study the tool wear mechanism in ultrasonic-assisted milling process and investigate the influence of the wear variable state of tool continuous cutting on the cutting process in ultrasonic-assisted milling and conventional milling. The experimental analysis showed that oxidation wear, adhesive wear, and diffusion wear occurred in ultrasonic-assisted milling; however, longer tool life was achieved when machining under the same conditions as compared to that of conventional milling. On the other hand, the curl angle of chip generated from ultrasonic-assisted milling was smaller than that from conventional milling in the same wear time. In addition, the burr produced by ultrasonic-assisted milling was not obvious, and under the coupling effect of ultrasonic-assisted milling, lower cutting force, improved surface roughness, and lower cutting temperature were obtained as compared to those of conventional milling under the same wear time.

A comprehensive study on flank wear progression of polycrystalline diamond micro-tool during micro end-milling of SiCp/Al composites

SiCp/Al composites are extremely difficult to process due to the existence of reinforced particles and the associated severe tool wear. The conducted experiments indicate that abrasive and adhesive wear are main flank wear types of PCD micro-tools in micro slotting end-milling of 45vol% SiCp/2024Al composites. Then, an analytical methodology incorporating two-body/three-body abrasive wear and adhesive wear is presented to estimate the PCD micro-tool flank wear land width in micro end-milling of SiCp/Al composites. The results show that adhesive wear is dominant at the initial machining stage, and two-body abrasive wear becomes the main tool flank wear mechanism at the later machining stage which takes about 60% of the tool flank wear under the given machining conditions. Besides, the effects of reinforced particles and machining/tool parameters on the tool flank wear progressions are analyzed.

Experimental Study on Tool Wear in Cutting Superalloy under High-Pressure Cooling

Superalloy is widely used in the aerospace industry and is a typical difficult-to-cut material. PCBN tool has good cutting efficiency in processing superalloy, but it has a larger cutting force, higher cutting temperature and severe tool wear in the cutting process. High-pressure cooling has great advantages in processing high strength steels such as superalloy, which can effectively reduce cutting temperature and improve tool-chip breaking performance, thereby reducing tool wear. Therefore, it is of theoretical significance and practical value to study tool wear mechanism of PCBN tool cutting superalloy under high-pressure cooling. Firstly, the wear form of the flank is analyzed to provide theoretical support for tool wear research; Secondly, the experimental study of tool wear under high-pressure cooling is carried out. The tool wear under different cutting time, cutting speed and cooling pressure is analyzed respectively, and the influence rule of different cutting conditions on tool wear is obtained; Finally, a tool wear prediction model under high-pressure cooling is established to provide theoretical basis and technical methods for efficient processing of superalloy and optimization of cutting parameters under high-pressure cooling.

An investigation on machined surface quality and tool wear during creep feed grinding of powder metallurgy nickel-based superalloy FGH96 with alumina abrasive wheels

In this study, the machined surface quality of powder metallurgy nickel-based superalloy FGH96 (similar to Rene88DT) and the grinding characteristics of brown alumina (BA) and microcrystalline alumina (MA) abrasive wheels were comparatively analyzed during creep feed grinding. The influences of the grinding parameters (abrasive wheel speed, workpiece infeed speed, and depth of cut) on the grinding force, grinding temperature, surface roughness, surface morphology, tool wear, and grinding ratio were analyzed comprehensively. The experimental results showed that there was no significant difference in terms of the machined surface quality and grinding characteristics of FGH96 during grinding with the two types of abrasive wheels. This was mainly because the grinding advantages of the MA wheel were weakened for the difficult-to-cut FGH96 material. Moreover, both the BA and MA abrasive wheels exhibited severe tool wear in the form of wheel clogging and workpiece material adhesion. Finally, an analytical model for prediction of the grinding ratio was established by combining the tool wear volume, grinding force, and grinding length. The acceptable errors between the predicted and experimental grinding ratios (ranging from 0.6 to 1.8) were 7.56% and 6.31% for the BA and MA abrasive wheels, respectively. This model can be used to evaluate quantitatively the grinding performance of an alumina abrasive wheel, and is therefore helpful for optimizing the grinding parameters in the creep feed grinding process.

An Experimental Study on Milling Titanium Alloy with a Revolving Cycloid Milling Cutter

In this paper, a revolving cycloid milling cutter was designed with a larger effective cutting helix angle and rake angle than a ball end milling cutter of the same diameter. This new type of milling cutter can solve the problems of low machining efficiency, severe tool wear, and low surface quality in titanium alloy processing. A comparison of the cutting performance of titanium alloys processed by the revolving cycloid milling cutter and the ball end milling cutter was carried out to obtain the variation laws of the cutting force and the processing surface quality under different tool wear conditions. The result shows that the wear zone of the revolving cycloid milling cutter is shallow and wide compared to that of the ball end milling cutter. As the wear speeds up, the spoon-shaped wear gathering zone found in the ball end milling cutter does not happen with the revolving cycloid milling cutter. The revolving cycloid milling cutter can significantly lower the axial force, the tangential force, and the ratio of the axial force to the tangential force with a stable cutting process.

Micro-texture design criteria for cemented carbide ball-end milling cutters

Given the serious work hardening phenomenon, high chemical activity, severe tool wear, and poor workpiece surface quality during the cutting of titanium alloys, placing micro-texture on the tool surface decreases the tool-chip contact area and friction and plays the role of wear resistance and friction reduction. In order to improve the cutting performance of cutting tools, the present study examins the effect of micro-texture parameters of a cemented carbide ball-end milling cutter on cutting force, tool wear, and workpiece surface roughness and establishes a regression analysis model via regression analysis. We consider the cutting performance of a cemented carbide micro-texture ball-end milling cutter as an evaluation standard. A genetic algorithm is applied to the multi-objective optimization of micro-texture parameters, and a regression analysis model of micro-texture design criteria is established. This provides a standardised reference to select standard micro-texture parameters in the design and preparation of a cemented carbide micro-texture ball-end milling cutter.

Cracking Behavior of Coating during Hot Tensile Tests of AlSi-Coated Press Hardening Steel

For industrial hot stamping applications, press hardening steel is usually coated with Al-10wt.%Si, in order to prevent substrate decarburization and oxidation at elevated temperatures. However, during hot stamping, the AlSi coating layer fractures, causing severe tool wear, substrate oxidation and increased friction coefficient between the tool and stamped part. The initiation of coating fracture can largely be attributed to the formation of several intermetallic compounds (i.e., FeAl & Fe2Al5) via Fe-diffusion, which also results in void formation throughout the coating layer. These intermetallics are formed mainly during the heating stage, with decreasing Fe-content from the coating-substrate interface. Due to distinctive thermo-mechanical properties of intermetallics compared to the steel substrate, the interaction between different intermetallics, including voids, causes high strain localization around the voids, leading to coating fracture. The goal of this study is to detect the initiation of cracks in a ~45 μm coating layer during uniaxial tensile deformation of a 1.5 mm AlSi-coated press hardening steel. For this purpose, isothermal tensile tests were performed at elevated temperatures. The coating cracks were detected by means of acoustic emission (AE) sensors during deformation. The distribution of coating cracks at hot stamping condition was examined via optical measurements. The tensile strain was measured from a strain grid on the sample gauge. The experiment involves heating the coated steel in a furnace to 920°C for 6 minutes, followed by uniaxial tensile deformation (at 600°C and 800°C), and finally quenching at ambient air. The first AE signal from the sample was observed during the tensile deformation at 600°C, indicating that tensile strain initiates fracture in the coating layer. At cooling stage, the temperature change with time triggered more AE signals, which may correspond to substrate phase transformation and additional fractures in the coated steel; the latter is owing to thermal expansion mismatch between the intermetallics in the coating layer, and steel substrate. Interestingly, no AE signals were observed during the heating stage; i.e., no coating cracks occur prior to deformation and quenching.

Investigation of the Influence of an Oscillation Superposition on the Wear Behaviour in an Industrial-like Process

In cold forging processes as well as in sheet-bulk metal forming, vast contact stresses result in severe tool wear and thus in tool failures. In order to achieve a sustainable production, a new manufacturing process is developed within the subproject T06 in the transregional collaborative research centre 73 at the Institute of Forming Technology and Machines (IFUM). In this subproject the influence of an oscillation superposition on a forming process is investigated. The new type of sheet-bulk metal forming (SBMF) process manufactures a component with internal and external gearing. Contact normal stresses and thus tool wear could be reduced by applying an oscillation superposition in the main force flow of the machine. To verify the positive results in other processes, the oscillation method is applied to an industrial-like process based on anchor bolt manufacturing of Fischerwerke GmbH & Co. KG. For this purpose, a representative tool system is developed using numerical simulation. The numerical simulation is also used to investigate resulting local contact stresses and relative sliding velocities. Furthermore, cylinder compression tests with and without oscillation superposition are conducted for the workpiece stainless steel 1.4362 (AISI S32304), in order to qualify the reduction of contact stress.

An overview of conventional and non-conventional techniques for machining of titanium alloys

Machining is one of the major contributors to the high cost of titanium-based components. This is as a result of severe tool wear and high volume of waste generated from the workpiece. Research efforts seeking to reduce the cost of titanium alloys have explored the possibility of either eliminating machining as a processing step or optimising parameters for machining titanium alloys. Since the former is still at the infant stage, this article provides a review on the common machining techniques that were used for processing titanium-based components. These techniques are classified into two major categories based on the type of contact between the titanium workpiece and the tool. The two categories were dubbed conventional and non-conventional machining techniques. Most of the parameters that are associated with these techniques and their corresponding machinability indicators were presented. The common machinability indicators that are covered in this review include surface roughness, cutting forces, tool wear rate, chip formation and material removal rate. However, surface roughness, tool wear rate and metal removal rate were emphasised. The critical or optimum combination of parameters for achieving improved machinability was also highlighted. Some recommendations on future research directions are made.

Tool reliability of sintered diamond drill bit for processing silicon carbide ceramics based on Bayesian theory

Silicon carbide (SiC) ceramics, as a superhard nonmetallic material, would induce severe tool wear during drilling. To ensure the quality of processing, the drill bits must be replaced in advance before failure, which leads to serious waste without effective usage. Aiming at the tool reliability problem determined by the tool wear during drilling of the high hardness nonmetallic materials, this article proposed a reliability analysis method of sintered diamond drill bit for machining SiC ceramics based on the distribution of tool degradation increment and the modeling of gamma process, and a tool reliability model of degradation increment was established based on the Bayesian theory. The drilling experiment of sintered SiC ceramics was carried out by sintering diamond drill bit to obtain the degradation increment data. The accuracy of the model was tested by the reliability model deviation rate, which indicated that the reliability model with considering individual differences was more accurate. This research can provide a theoretical model and analytical method for improving the reliability of the nonmetallic brittle material processing tools.

Study on effect of vibration amplitude on cutting performance of SiCp/Al composites during ultrasonic vibration–assisted milling

Silicon carbide particulate reinforced aluminum (SiCp/Al) matrix composites play an important role in aviation, aerospace, electronics, automobile, and other fields due to their outstanding mechanical properties. However, the existence of reinforcing SiC particles leads to poor cutting performance, terrible surface quality, and severe tool wear of SiCp/Al composites. In this study, a series of experiments were carried out with an ultrasonic vibration–assisted milling (UVAM) experimental device to study the effect of amplitude on the machinability of 20% SiCp/Al composites from four aspects: cutting force, surface roughness, surface morphology, and chip morphology. The results showed that it had a great influence on cutting force, surface roughness, surface morphology, and chips when the amplitude increased to 3 μm. The surface of workpiece material deteriorated rapidly and presented the fragmentation. In addition, a large number of micro-cracks and particle bulges appeared on the machined surface. It was suggested that the amplitude below 5 μm had a negative impact on the milling surface quality of 20% SiCp/Al composites, and the amplitude of 3 μm was considered as a critical value.

Sustainable production of dry-ultra-precision machining of Ti–6Al–4V alloy using PCD tool under ultrasonic elliptical vibration-assisted cutting

The Ti–6Al–4V alloy is regarded as a typical hard-to-machine material owing to its small thermal conductivity and low deformation coefficient. Large amounts of cutting fluids are required and consumed in the traditional ultra-precision machining of the Ti–6Al–4V alloy to reduce the cutting temperature and inhibit tool wear. Negative effects, such as environmental pollution and hazards to operator, follow behind owing to the use of cutting fluids. Dry machining is considered as the ideal environmentally friendly machining strategy. However, traditional dry-ultra-precision cutting (TDUC) of Ti–6Al–4V alloy is not practical because of the rapid deterioration of surface integrity and tool life induced by extremely high cutting temperature. In this paper, a novel machining technology known as ultrasonic elliptical vibration-assisted cutting (UEVC) was adopted for overcoming the machining difficulties in the TDUC process of Ti–6Al–4V alloy. Moreover, the commercial polycrystalline diamond (PCD) tool was employed to achieve more economical and sustainable production. Thanks to the effects of UEVC technology, the cutting and friction forces were significantly reduced, and the generated cutting heat quickly dissipated, which caused a great reduction of the cutting temperature. Thus, the pressure of tool damage was relieved. The experimental results indicated that, when the UEVC technology applied in the TDUC process, the tool wear was observably suppressed, the surface integrity was significantly improved. And an undamaged ultra-precision finished surface with a roughness value less than 30 nm was produced. Besides, the shorter, regular and breakable chips were obtained, and achieving a better chip control. Conversely, the TDUC process provoked poor surface quality, severe tool wear, and long, irregular, and unbreakable chips. Therefore, the proposed machining technology minimizes the negative effects induced by the use of cutting fluids, and provides sustainable process for dry-ultra-precision machining of Ti–6Al–4V alloy in practical application.

Experimental Study on Deep Hole Drilling of TC18 Titanium Alloy Based on BTA

TC18 titanium alloy has problems such as difficult chip removal and chip removal, severe tool wear and skew of the hole axis during deep hole machining, which seriously affects the surface quality of the inner hole. Therefore, this test carried out the BTA deep hole drilling test for TC18 titanium alloy, and studied and analyzed the problems of chip shape change, tool wear and hole axis deflection during machining. The test results show that the chip shape is longer and more developed with the increase of the spindle speed, and the bending is longer and more curved with the decrease of the feed amount; the tool wear is serious during the drilling process, and the reasonable process parameters can reduce the wear of the tool; The cutting force, the rigidity of the drill pipe and the arrangement of the guide blocks are important factors affecting the deflection of the hole axis.

Influence of micro grooves of diamond tool on silicon cutting: a molecular dynamic study

ABSTRACTDuring single-point diamond turning of hard and brittle materials, tool wear is a dominant factor that influences machinability. In the wear process, micro grooves on the flank face is an important character of tool wear, which leads to the formation of subcutting edges and the ductile to brittle transition. In this paper, classical molecular dynamic simulations of nanometric cutting of silicon by a diamond tool with V-shape grooves were carried out to explore the effect of groove geometry on the workpiece and tool integrity. The evolution of tool wear and machined surface integrity was discussed. Simulation result shows that grooves have a significant influence on the stress and temperature distributions of the tool, which has a great influence on tool deterioration. Grooves with sharp edges will lead to severe tool wear and bring deep subsurface damage of the machined surface. However, the subsurface damage of the machined surface can be restrained with blunt grooves since the pressure is reduced. With a comprehensive understanding and controlling of groove, tool wear can be suppressed and high-quality surface can be achieved.

Investigate on effect of cryogenic cooling on oxidation wear of WC-Co carbide tool milling titanium alloy

For titanium alloy at high cutting speed, the severe tool wear will ineluctably take place diminishing the available tool life because of the high instantaneous temperature rise. Especially the WC-Co material in carbide tool will be reacted with the oxygen element in the air and generate oxide, and the tool oxidation wear is inevitable. In milling Ti–6Al–4V alloy operations, this article presents the first comprehensive investigation on the oxidation wear effect of cryogenic cooling on carbide tool compared with the conventional cooling. Based on the Gibbs free energy of the chemical reaction, the machining characteristics of the oxidation reactions were analyzed in detail. A series of machining testes were executed adopting controllable cryogenic cooling milling system. The surface and cross-section morphology and phase composition characteristics of tool were measured by SEM and XRD measuring equipments, as well as the oxidation wear mechanism of tool in cryogenic cooling. The results show that the thermal oxidation degree of the elements of WC-Co is higher in the conventional cooling processing. After cryogenic cooling intervention, oxidation reactions in tool are reduced significantly. Even the most probable reaction is disappeared, and the oxidation degree is decreased. When the temperature drops to 180 K, it has the best cooling effect. In cryogenic, the effective binding of WC crystal particle to the adhesive phase Co is a major factor for inhabiting oxidation wear of tool. The investigations indicate that the cryogenic cooling method can effectively inhibit the oxidation effect of carbide tool in milling titanium alloy process, and it improves the resist oxidation ability of tool.