Rake Face Wear Research Articles

Performance of PCBN tools in dry cutting iron-based superalloy

A range of PCBN tools were utilized for turning iron-based superalloy in dry environment and their cutting performance was researched from the perspective of tool wear, tool life, cutting force, cutting temperature, and machined surface roughness. The experimental results revealed that the cutting temperature increased, while the resultant cutting force exhibited an initial rise followed by a decline as the cutting speed increased. The PCBN tools with TiC or TiC+SiCw ceramic bonding agent and low CBN content (≤65 %) were chipped and even fractured in the preliminary stage of the cutting process and were not suitable for cutting the iron-based supperalloy. The PCBN tools with Co-W-Al ceramic bond agent and high CBN content (85 %) performed well in the cutting process, while for every 50 m/min increase of cutting speed, tool life was reduced by approximately a half. An exceptional surface quality could be achieved using this specific type of PCBN tools. However, once the wear value of the flank faces reached about 0.25 mm, the surface roughness began to increase noticeably. In order to achieve higher surface quality, the suggested cutting time for continuous dry cutting iron-based superalloy using the PCBN tools at different cutting speeds was obtained. Rake face wear was dominated by adhesion, chipping, flaking and grooving, and built-up-edge and microcracks also appear at relatively higher cutting speed. Flank face wear showed brittle flaking off at the lower cutting speed (50 m/min), while when cutting speed was increased (100 m/min-200 m/min), abrasion and adhesion wear were dominant.

Finite element investigations for chip scraping during orthogonal cutting process with micro-textured tools

Compared with the conventional tool (CT), the micro-textured tool (MTT) has the advantages of reducing cutting forces, lowering cutting temperatures and inhibiting tool wear. However, the chip scraping phenomenon generated in the cutting process has negative effects and degrades cutting performance when using the MTT with grooves perpendicular to the cutting edge. Due to the difficulty in observing and characterizing chip scraping in situ by experiments, its mechanism and influence on specific cutting forces and tool wear are not fully understood. To this end, finite element (FE) method is employed for simulating the cutting process with MTT. The simulation model is validated by comparing the predicted and measured specific cutting forces. The average prediction error of specific cutting and feed forces is 12.4 % and 18.8 %, respectively. The simulation results indicate that chip scraping mainly results from the discontinuity, non-uniformity and high contact stress state of the tool-chip interface. The minimum specific cutting force is achieved when the advantages of micro-texture and the chip scraping effects are balanced. The MTT rake face wear is subdivided into a severe and a sliding wear zone. This partition characteristic is closely associated with normal contact stress and temperature distributions. The work in this paper contributes to improving the understanding of chip scraping, optimizing micro-texture and cutting parameters, and promoting MTT applications in the manufacturing industry.

Wear characteristics and performance in side milling of Ti2AlNb intermetallic alloys with coated and uncoated end mills

Ti2AlNb intermetallic alloy is highly suitable for aerospace key component manufacturing due to its low density, exceptional temperature strength, high specific strength, and creep resistance. However, the poor machining quality and severe tool wear appear, because of their poor thermal conductivity and excellent high temperature strength performance. In this paper, the coated and uncoated end mills are performed to investigate the tool wear characteristics during side milling of Ti2AlNb intermetallic alloys. In addition, the milling forces, tool service life, tool wear morphologies and mechanisms are discussed in detail. Results indicate that the coated and uncoated end mills suffered severe tool wear in the side milling process, leading to a rapid increase in milling forces. The coated end mill exhibited a longer service life of tools than the uncoated end mill. The service life of coated end mill reaches 6 min, primarily limited by flank wear and accompanied by chipping, whereas the uncoated end mill had a service life restricted to 2 min due to tool tip breakage. Tool wear morphologies of coated and uncoated end mills include rake face wear and flank face wear. Typical characteristics (e.g., crater wear, built-up edge, chipping and adhesion) are observed on the rake face of the both coated and uncoated end mills. On the flank face of the coated end mill, the chip adhesion, micro-chipping, chipping and coating delamination are found, whereas only chip adhesion and micro-chipping appear for uncoated end mill. Furthermore, the primary mechanisms of wear for both coated and uncoated end mills are adhesive wear and oxidation wear, which occur on both the rake face and flank face.

An Evaluation of the Tool Wear of Ceramic and Coated Carbide Inserts in Finishing Turning under the Influence of Age-Strengthening Gray Cast Iron

Gray cast iron (GCI) is a common material in the automotive industry due to its mechanical characteristics, which change primarily for materials employed for the foundry and cooling rate of material. According to the workpiece, the material of the cutting tool and cutting parameters are analyzed to improve the machining and to increment the lifetime of the tools. In this research, the foundry and machining process of an automotive component using ceramic and coated carbide tools were the study case, and the effect that they have on the age strengthening of GCI on the tool wear of the cutting tools was studied. Both inserts have the capability to machine the material with a rough surface between 1.5 to 2.0 μm. The wear mechanism of inserts and the microstructure of GCI were characterized with microscopy techniques, atomic force microscope (AFM), and energy dispersive X-ray spectroscopy (EDS). The microstructure of the workpiece shows a casting with flake graphite morphology that is linked with the induction of microcracks in the material. The experimental analysis shows that the GCI with 12 days of aging has an increased tensile strength. This improves the tool life of ceramic and coated carbide tools. There is a 50% reduction in flank wear with inserts that are machined with the GCI within five days of aging, compared with the material within twelve days. The rake face and flank wear show that abrasive and adhesive wear are the main mechanisms of ceramic inserts due to the high cutting speed. Meanwhile, adhesive and oxidative wear in the flank were the predominant type of wear for coated carbide tools.

Tool life and wear mechanisms of CVD coated and uncoated SiAlON ceramic milling inserts when machining aged Inconel 718

In this study, an investigation has been conducted to fully characterise for the first time the tribological benefits of adding two different types of chemical vapour deposition (CVD) coatings to silicon aluminium oxynitride milling inserts with a chemical composition of (Si3N4 + Al2O3 + Y2O3), known by the trade abbreviation ‘SiAlON’, typically used to cut difficult to machine materials such as Inconel 718. The experimental tests compared the tool life, material removed and wear resistance of the two different CVD coated inserts against that of uncoated SiAlON ceramic milling inserts. Coating A was a multilayer CVD coating and had a composition of (TiN + TiCN + Al2O3), Coating B was a bilayer CVD coating and had a composition of (Al2O3 + TiN). It was determined that at 900 m/min the uncoated SiAlON ceramic milling inserts exhibited the least amount of wear and variation in cutting force when milling precipitation hardened Inconel 718 samples. Coating A demonstrated significantly lower adhesion to the SiAlON substrate but had higher tool life and material removal rates, Coating B demonstrated excellent adhesion to the SiAlON substrate. The interfacial bonding of Coating B allowed for much higher adhesion to the substrate, but it suffered from much lower tool life and higher rates of rake and flank face wear. The flank wear measurements concluded a cutting speed of 900 m/min to be the optimum cutting speed for machining Inconel 718 with uncoated SiAlON ceramic milling inserts.

Multi-Objective Optimization Design of Micro-Texture Parameters of Tool for Cutting GH4169 during Spray Cooling

This study explores the performance of micro-textured tools when cutting GH4169 during spray cooling. First, the morphologies of the micro-textures were selected according to the simulation and experiments. Secondly, cutting experiments were carried out during spray cooling. As appropriate for each experiment, regression models of cutting force, cutting temperature, or tool wear area were established, and variance analysis was conducted. The cutting force, cutting temperature, and tool wear area functions were obtained from the respective regression models. Based on these functions, the micro-texture parameters were optimized using the response surface method with the cutting force, cutting temperature, and rake face wear area as the objectives. Finally, a full factor experiment on the micro-texture parameters was designed using Minitab, and cutting experiments were conducted using micro-textured tools with these parameters. Taking a relatively low cutting force, cutting temperature, and tool wear as the objectives, a genetic algorithm multi-objective optimization model for the micro-texture parameters of the tools was established, and the model was solved using the NSGA-II algorithm to obtain a Pareto solution set and micro-texture parameters with a good, comprehensive cutting performance. The micro-texture morphology and parameters obtained in this study can also be used for cutting other high-temperature alloy materials with similar properties to GH4169. This research method can also be used to optimize micro-textured tools for cutting other materials.

An adaptive method of measuring the rake face wear of end mills based on image feature point set registration

An acceptable tool wear evaluation and acquisition approach is critical for developing an accurate, rapid, and practical online tool wear prediction system. The one-dimensional crater wear depth is difficult to quantify, and relying solely on flank wear width is very simplistic. External conditions such as vibration and illumination have a large impact on two-dimensional wear area and three-dimensional volume. In practice, these are difficult to successfully characterize tool wear. This work proposes a two-dimensional rake face edge loss area as an additional indicator to assess milling cutter wear. An adaptive measurement approach based on 2D image feature point set matching is presented to suppress the area calculation error caused by image position offset and chips or built-up edges. 201 images were collected in two groups of cutting experiments for comparison with the proposed method and the other two methods, manual registration and non-registration. The results show that the proposed method's measurement values are closer to the actual values and have a higher measurement efficiency. Furthermore, the proposed indicator is sensitive to micro-scale changes to the blade edge, especially at the tip, and can be used as a supplement one to monitor tool wear more comprehensively.

Durability of micro diamond tools with different crystallographic planes

Micro diamond tools are indispensable for machining microstructured arrays. The cutting edge durability and consistency of micro diamond tools are the determinants of the microstructure quality and accuracy, in addition to the motion accuracy of the machine tool. A strength distribution model of the working area including the cutting edge and rake and flank faces was established considering diamond anisotropy and chip flow direction. Comprehensive wear resistances of micro diamond tools with different crystal orientation combinations were analyzed based on the model, and the wear prone areas of different tools were successfully predicted. The evolution processes of the sharpness and wear topography were monitored for every micro diamond tool in the micromachining experiments. The morphologies, profile errors and topological characteristic of the microstructures machined with different micro diamond tools with increasing cutting distance were analyzed. Finally, a conclusion was drawn that the wear resistances of the micro diamond tools in ascending order are Aγ{100}Aα{100}, Aγ{100}Aα{110}, Aγ{110}Aα{100}, and Aγ{110}Aα{110}. The three working areas of the Aγ{100}Aα{100} tool are prone to wear; in contrast, those of the Aγ{110}Aα{110}tool are resistant to wear. The tool wear of Aγ{100}Aα{110}is caused by flank face wear, and that of Aγ{110}Aα{100} is caused by rake face wear.

Vibration based characterization of tool wearing in micro-milling of ceramics during waveform toolpath

The main aim of the paper is to monitor the micro- milling tool wearing process offline, by a microscopic tool measurement on one hand, and using high-frequency vibration measurement online, during the cutting process, on the other. Relations between the rake face wear stages and the measured online and offline parameters were determined applying an owndeveloped, artificial neural network based feature selection solution. As the main result, the experiment-based research appoints that the measured vibration variable component(s) which characterizes the key, three tool wearing phases, in the same way as the real rake face wearing stages occur, applying the waveform tool path

Simulation and Experimental Research on Carbide Tool’s Rake Face Wear of Cutting 2.25Cr1Mo0.25V Material

Due to the high temperature toughness and low thermal conductivity of 2.25Cr1Mo0.25V material, the rake face of the tool can easily wear out during the cutting process, which reduces the service life of the tool. In this paper, by analyzing the contact behavior, heat exchange conditions and tool wear mechanism during the cutting process, a 3 D finite element simulation model of tool wear in accordance with the actual cutting process is established. Combined with the cutting wear experiment, the validity of the model is verified. The influence of cutting speed, cutting depth, feed rate and the interaction between them on rake face wear was studied by designing a simulation scheme. The simulation results show that: With the increase of cutting speed and feed rate, the wear depth of the tool's rake face gradually increase, but for cutting depth, the depth of wear gradually decreases. The interaction of cutting speed and feed rate has a significant influence on the rake face wear, the interaction between cutting speed and feed rate, and the interaction between feed rate and cutting depth are not significant. The research results provide a theoretical basis for improving the service life of the tool and provide technical guidance for the selection of cutting parameters in the actual production.

Performance of carbide tools in high-speed dry turning iron-based superalloys

Machining quality and productivity of superalloys are limited due to their poor machinability, and fewer studies have focused on the cutting of iron-based superalloys. In this study, the cutting performance of coated and uncoated carbide tools in high-speed dry turning iron-based superalloy GH2132 was investigated by performing a series of cutting experiments. The experimental results indicated that cutting temperature and cutting forces increased, while tool life decreased with the increase in the cutting speed from 30 to 100 m/min. Under relatively low cutting speeds, flank face wear was dominated by abrasion and adhesion, while rake face wear mainly involved built-up edge (BUE), built-up layer (BUL), adhesion, and breakage near the depth of cut. Under higher cutting speed, adhesion wear was more serious on the flank face, and peeling off of the coatings and substrate occurred on the rake face. Owing to the protective effect of (Ti, Al)N + TiN coating, the coated tools exhibited better wear resistance and thus longer tool life, in particular, under higher cutting speeds. Analysis of the tool wear gap in the horizontal direction indicates that better dimensional accuracy could be obtained when coated tools are used. In dry turning of GH2132 with carbide tools, a favorable surface finish could be obtained. The surface roughness roughly showed a tendency to first decrease and then increase with the increase in average flank wear. The coated tools should be avoided to machine GH2132 at higher cutting speed due to the poor surface finish.

The effect of micro-texture on wear resistance of WC/Co-based tools during cutting Ti-6Al-4V

Titanium alloy as an important material used in the aerospace industry and automotive field has many advantages such as excellent specific strength, good corrosion resistance, and ultra-low temperature performance. However, there are still some difficulties during the cutting of Ti-6Al-4V, such as severe tool wear which reduces the surface quality of work piece. Textures could protect the tool from further wear and improve the tool life, and cutting productivity. In this work, femtosecond laser was used to make textures with different orientations (vertical, parallel, and vertical to the main cutting edge) on the rake face of carbide-tipped cutting tool to research the influence of different textures directions on the cutting performance. The results found that using parallel textured tools could reduce the friction coefficient by 14%. Compared with untextured tools, the rake face wear of parallel textures tools is reduced by 35–70% and surface roughness improved by 29%, which is owned to smallest the tool-chip contact area of tool with parallel microstructure.

Cutting performance and wear mechanisms of TiAlN PVD-coated cemented carbide tool in high speed turning of Ti-5Al-2Sn-2Zr-4Mo-4Cr alloy

The high-speed finish turning tests of Ti-17 titanium alloy (Ti-5Al-2Sn-2Zr-4Mo-4Cr) were carried out by using PVD cemented carbide tools with TiAlN coating. The machinability behaviors in terms of cutting forces, cutting temperatures, surface roughness, and tool service life were measured and evaluated under different machining parameter conditions, and the empirical prediction model of these variables were established depending on the cutting parameters. Incorporating the measured results of scanning electron microscopy (SEM) as well as energy dispersive spectroscopy (EDS), the initial tool wear patterns and the eventual wear patterns when the tool wear states meet the failure criteria were comparably investigated and analyzed. It was found that during the initial wear stage, the sticking wear zone and the sliding wear zone can be distinguished on the tool wear interface. The main wear patterns of are peeling off of coating material, crater wear of rake face, edge breakage and edge wear of tool tip after reaching the tool failure rejection criterion. The cutting tool wear mechanisms were systematically studied, and the results show that the wear mechanisms of a TiAlN PVD-coated carbide cutting tool in turning Ti-17 titanium alloy were dominated by the interaction wear effect among the adhesion, oxidation and diffusion between cemented carbide substrate and workpiece material.

Cutting performance of cubic boron nitride-coated tools in dry turning of hardened ductile iron

A novel cubic boron nitride (cBN)-coated silicon nitride(Si3N4) cutting tool was fabricated via the diamond interlayers by electron cyclotron resonance (ECR) microwave plasma chemical vapor deposition (MPCVD) technique. The cutting performance of cBN-coated tools was evaluated by dry turning of hardened ductile iron in comparison with the commercially available titanium aluminum nitride (TiAlN)-coated tools. The effects of cutting parameters on the cutting force and cutting temperature were studied. The results showed that the cutting forces increased with the increase of depth of cut but decreased with the increase of cutting speed, while the cutting temperature increased with the increase of cutting speed. Compared to the TiAlN-coated tools under identical turning conditions, the cBN-coated tools had lower cutting force and cutting temperature, and smaller tool wear. The cBN-coated tools delivered excellent cutting performance and prolonged tool life. Furthermore, the wear patterns and wear mechanisms of cBN-coated tools were investigated. It was found that the dominant wear patterns were crater wear on rake face and flank wear land, and the wear mechanisms were demonstrated to be abrasion wear and diffusion wear. The cutting experiments verified that the cBN-coated tools had attractive potentials in the applications for dry turning of refractory metals and hardened ferrous materials.

Impact of cutting tool wear on residual stresses induced during turning of a 15-5 PH stainless steel

Abstract Finish turning is one of the key operations governing the residual stresses below the machined surface. The residual stress state depends on the cutting conditions and on the selected cutting tool system, i.e. macro geometry, cutting edge preparation as well as tool grade. However, tool wear often affects the interaction between the tool and the workpiece leading to severe modifications of the residual stress state. This work aims at investigating the influence of cutting tool wear on the surface integrity in longitudinal turning of a 15-5PH stainless steel. First, an experimental sensitivity study is performed to assess the effect of various wear modes on the residual stresses. Then a numerical model has been developed to understand the experimental observations and connect them to the thermomechanical loadings and local data within the near surface. The impact on residual stresses of three types of wear were tested (flank face wear, rake face wear and adhesion on the cutting edge) with the same cutting condition (Vc =120m/min, ap = 0.2 mm and f = 0.2 mm.rev-1). Based on the experiment, the numerical simulation proposes to observe the impact of wear on thermomechanical loadings by simulated a tool with a rounded cutting edge, a crater on the rake face and high flank face contact length. It follows that the impact of the rake face wear is extremely low, contrary to the rounded edge or the flank face wear which increased the contact length and significantly impact the loadings.

A Study on New Surface Textured Tools for Inhibition of Derivative Cutting

Abstract Derivative cutting is a texture-edge cutting of chip bottom side, which happens all the time in machining with textured tools. Two new types of textured tools are developed and fabricated: a micro-textured tool with chamfered texture edge (CTE) tool and a multiscale textured (MSTT) tool with the texture surface below the rake face. The effectiveness of the tools on inhibiting derivative cutting is investigated at different cutting velocities. For the CTE tool, the inhibiting effect is more pronounced with the increase in the chamfer angle, but the severe rake face wear eventually leads to the occurrence of derivative cutting. Compared with the CTE tool, the multiscale textures of the MSTT tool provide more sustainable effectiveness in inhibiting derivative cutting. The inhibition mechanisms of the two types of textured tools are discussed.

Study on mechanism and theoretical model of tool wear in fluorophlogopite glass-ceramics turning

Based on the principle of tribology and the turning test of fluorophlogopite glass-ceramics, the furrow effect wear mechanism for the tool wear in turning brittle materials was proposed and the friction coefficient model between the tool tip wear surface and the workpiece surface was established. The wear form is mainly reflected in the rake face wear and the tool tip wear. It develops the two-dimensional wear into three-dimensional wear, so that the relationship between tool strength and wear can be examined more scientifically. Combined with geometry and kinematics analysis, the wear volume model of turning tool for brittle materials is established and tested. Both theoretical and experimental results show that with the increase of cutting speed, cutting depth and feed rate, the wear volume of the tool increases first, then decreases to a critical value, after that, the wear volume of the tool increases sharply. The sensitivity of wear volume to cutting speed is the highest.

Study on secondary cutting phenomenon of micro-textured self-lubricating ceramic cutting tools with different morphology parameters formed via in situ forming of Al2O3-TiC

Setting the micro-texture in the cutter–chip contact area of a micro-textured tool rake face can effectively improve the tool’s cutting performance. However, an unreasonable design for the micro-groove morphology and size and the selection of inappropriate cutting parameters will cause a secondary cutting phenomenon during the cutting process. To explore the optimum micro-texture morphology size and cutting parameters, micro-texture self-lubricating ceramic cutting tools with different morphology parameters (micro-texture location distribution: MSTD-1, MSTD-2, MSTD-3; groove spacing: MSTS-1, MSTS-2, MSTS-3; groove width: MSTW-1, MSTW-2, MSTW-3) were formed in situ and by hot pressing sintering, and a dry cutting 40Cr comparison test with a non-textured tool (MST-0) was conducted. The results revealed that the MSTD-2 tool effectively reduced the cutting force, friction factor, and rake face wear and relieved the secondary cutting phenomenon while cutting 40Cr. A theoretical analysis showed that the micro-texture morphology parameters and cutting speed were the main factors affecting the secondary cutting, with a smaller groove width and higher cutting speed associated with a lighter chip impact.

Effect of microhole-textures filled with graphite on tribological properties of WC/TiC/Co carbide tools

To expand the industrial application of cemented carbide, micro-EDM was utilized to machine microhole-textures on the carbide surface; graphite powder was burnished into the textured microholes. The tribological properties of the microhole-textured tool combined with graphite were investigated and compared with the conventional one by carrying out reciprocating sliding friction tests and dry machining tests. Results exhibited that the microhole-textured tool combined with graphite possessed a much lower friction coefficient than that of the conventional one in sliding tests. The cutting forces, average friction coefficient at the tool–chip interface, and rake face wear of the textured tool were reduced, and the workpiece surface quality was also slightly improved. The worn regions of carbide specimen were examined and studied, and the possible effect mechanisms for the enhancement of friction and wear properties mainly consisted of the formation of uneven graphite film by friction extrusion, reduction of actual contact length, entrapment of wear debris and supply of graphite lubricant.

Steady tool wear and its influence on tool geometry in ultra-precision fly cutting of CuZn30

In ultra-precision fly cutting (UPFC), steady tool wear progresses gradually when cutting ductile materials. The steady wear of diamond tools changes the tool geometry, and further affects the topography of the machined surface. In this study, a theoretical and experimental investigation was conducted on the forms of steady tool wear and their influence on the tool geometry in UPFC. The features of steady tool wear in UPFC were investigated, the displacement of the cutting edge under the effects of tool flank wear was modeled, and factors affecting the cutting edge roundness were investigated. The study results indicate the following: (1) the features of steady tool wear in UPFC include crater wear on the rake face, smooth and flat wear on the cutting edge, and flank wear on the tool clearance face. (2) A smooth wear-land on the cutting edge changes the top rake of the cutting tools, whereas flank wear on the tool clearance face affects the clearance angle and roundness of the cutting edge. (3) The maximum width of the tool material loss zone, the nose radius of the original fresh cutting edge, and the arc angle of the wear-land have a certain influence on the nose radius of the worn cutting edge. The results of this study will provide deep insight into steady tool wear and its influence on the tool geometry, which can potentially be used to predict or evaluate the finish of a machined surface under tool steady wear.