Tool Rake Face Research Articles

Sustainability and tool wear of titanium alloy thread cutting in dry and cryogenic conditions

The article is devoted to the study of the effect of cryogenic cooling on the tool wear in thread turning tests. The tool wear and its influence on the thread accuracy were investigated. Two different grades of titanium alloys were used for comparative purposes. The excellent performance characteristics of titanium alloys pose machining problems, causing high unit forces at the edge of the tool leading to chipping and premature tool failure. In turn, the low thermal conductivity of pure titanium affects the heat distribution in the cutting zone. The heat is not absorbed by the material being machined but accumulates in the tool, causing an increase in diffusion and chemical wear. The results of cutting tests using liquid nitrogen showed lower values of wear on the major and minor tool flank. The edge reduction of the tool was also significantly less during cryogenic machining. The analysis of the formation of wear marks and the blade wear mechanisms was carried out for the tool rake face. The tests were carried out using the SEM method and confirmed by EDS analyses. In order to compare the course of tool wear over time, a mathematical model was developed, which results from the course of phenomena during cutting. It consists of two complementary equations. The first equation is characteristic for the first cutting phase and results from the loads imposed on the blade and aims at thermodynamic equilibrium. It is a period of stable tool operation and constant wear intensity. The second equation concerns crossing the equilibrium point followed by the process of accumulation of elementary wear phenomena. These phenomena accumulate until the blade is completely worn-out. The use of blade wear development models to determine the expected blade life allowed to confirm the beneficial effect of cryogenic cooling on the course of the blade wear process when cutting threads for two different titanium alloys.

Experimental study on role of tool-work materials and machining conditions on Built-up Edge Formation

Built-up Edge is a well-known phenomenon in the manufacturing industry which probably a danger for the quality of the semi-finished or finished product. This unfavourable incident hampered surface finish and reduce the life f tool. During any machining operation such as turning; the tool and the performed blank stick together like welding action. Under high compressive stress, seizure keeps the material from sliding over the cutting tool rake face. The presence or non-appearance of a developed edge (BUE) is significant according to apparatus wear and surface completion. The potential systems and cycles of wear impacted by the various kinds of the built-up edge were talked about in our study. Metallographic examinations have indicated that recrystallization happens in the streamed layer. The progression of sub microscopic crystallites over the tool-face affects tool wear. From the experiment, the most positive cutting conditions, from the perspective of both wear and surface completion, happen without a developed edge. This work and moderate reports on the investigation of the BUE calculation of C30 steel machined at low rates with and without a cutting liquid.

The Research of Tool Wear Mechanism for High-Speed Milling ADC12 Aluminum Alloy Considering the Cutting Force Effect.

Tool wear is a major cause of accelerated tool failure during the milling of aluminum alloy. The periodically cutting force directly affect the cutting heat and tool wear due to the intermittent cutting characteristics of the milling process. The focus of this paper is to analyze the influence of the variation of cutting force on tool wear behavior. The change law of cutting force by cutting parameters was analyzed firstly. Secondly, the variation of the wear land width (VB) of tool flank face by the milling length was analyzed. Thirdly, the wear morphology and the energy dispersive spectrometer (EDS) results of tool rake face and flank face in different cutting parameters were observed by tungsten filament scanning electron microscope. Finally, considering the cutting force effect, the tool wear mechanism during high-speed milling of Aluminum-Alloy Die Castings 12 (ADC12, 12 means aluminum number 12) was analyzed. The cutting force in tangential direction is predominant during high-speed milling aluminum alloy, which decreases gradually with the increase of cutting speed but increases gradually with the feed rising. The adhesion-oxidation wear was main wear mechanism of tool rake face during high-speed milling. While adhesive wear was the main wear mechanism of the tool flank face during high-speed milling. It is found that the formation of adhesive wear is the process from particle adhesion to melting until the formation of adhesive layer, which related to the change of cutting force.

State of the art of tool texturing in machining

In most of the machining processes, the application of surface texturing is one of the most remarkable and promising research fronts in relation to the use of tribological concepts for improving machinability. This paper aims to review the most recent articles on this theme (from 2016 to date) to assist the researchers in the state of the art of this technology, guide the forthcoming related investigations, and thus, fill the identified research gaps. The texture effect in machining was comprehensively reviewed considering chip formation, cutting forces, cutting temperature, lubrication, surface integrity, and tool life. The present review highlights and summarizes the major findings with emphasis on the influencing parameters, such as workpiece and tool material, cutting process, lubri-cooling condition, texture geometry, and texture manufacturing technique. The overwhelming majority of the studies presented tool surface textures manufactured by laser ablation on the rake face of uncoated WC-Co tools. In this relation, turning was identified as mostly used machining process and dry condition as the chiefly implemented lubri-cooling environment. Moreover, most of the textures were noticed with linear grooves and dimple geometries, whereas the work materials mostly investigated were the hardened/high alloy steels and titanium alloys.

Design of a diamond tool for laser in situ assistance

Laser in-situ auxiliary processing is an advanced hard and brittle material processing method. In order to improve the utilization rate of the laser in the processing process and better realize the thermal softening effect on hard and brittle materials, the transmission model of the laser and diamond tools was established by COMSOL, and the laser transmission through the rake face of the ordinary arc-edged diamond tool was analyzed. A diamond tool with laser incident surface parallel to the rake surface is designed. The laser incident surface of this diamond tool is parallel to the rake surface, so that the laser can penetrate the diamond rake surface perpendicularly, which is compared with the ordinary circle. The arc turning tool can significantly improve the beam quality, increase the power density of the laser penetrating the tool, and obtain the temperature field change of the diamond tool during laser irradiation and the rule of tool tip deformation. The research is to improve the laser in-situ assisted diamond tool Machining accuracy provides theoretical basis.

Thermal modelling of cutting tool temperatures and heat partition in orthogonal machining of high-strength alloy steel

Cutting temperatures and heat partition into the cutting tool are critical factors that significantly affect tool life and part accuracy during metal removal operations, especially in dry machining. Among many thermal modelling studies, uniform heat partition ratio, and/or uniform heat intensity along the tool-chip interface are frequently assumed. This assumption is not valid in actual machining and can lead to erroneous estimated results in the presence of sticking and sliding friction zones. Therefore, it is necessary to accurately predict the cutting tool temperature and heat partition during machining. This paper presents an analytical thermal modelling approach which considers the combined effect of the primary and the secondary heat sources and determines the temperature rise and non-uniform heat partition ratio along the tool-chip interface. Cutting tests were conducted on AISI/SAE 4140 high-strength alloy steel using carbide cutting tools over a wide range of cutting speeds. Cutting temperatures were measured experimentally using an infrared thermal imaging camera. Experimentally established sticking and sliding friction regions were used to evaluate non-uniform frictional heat intensity along the tool-chip interface. The temperature matching condition along the tool-chip interface leads to the solution of distributed non-uniform heat partition ratio by solving a set of linear equations through programming in MATLAB®. Experimental results show to be consistent well with those obtained from the thermal model, yielding a relative difference of predicted average tool-chip interface temperature from −0.8% to 6.3%. It is found that average heat partition into the cutting tool ( RT) varies from 35% down to 15% for the entire range of cutting speeds. These results suggest that, to address the thermal problem in metal cutting, the research and development of tooling should also focus on reducing friction on the tool rake face in addition to the contribution of the combined effect of primary and secondary heat sources on temperature rise at the tool-chip interface.

Model of the Ultimate Stress State of the Coated Tool Cutter Material

The article proposes a model of the ultimate stress state of the material of the coated tool cutter. It is found that with an increase in the fracture toughness of a tool in connection with the material ductility the machining accuracy deteriorates due to arising elastic-plastic vibrations of the tool cutter. In case when no ultimate stress state is reached, that is, a tool operates in the elastic region, then an alternating stress distribution diagram is realized for the tool cutter at the beam approximation. Therefore, in addition to the frictional vibrations, arising from the interaction between the tool cutter and a workpiece, the elastic vibrations can arise, which affects the machining accuracy and the service life of the coated tool cutter. The use of coatings makes it possible not only to increase the wear resistance of cutting tools, but also to transform the stress distribution diagrams of the normal σN and tangential τγ contact stresses acting on the rake face of the cutting tool. In particular, it is possible to control the length of the total contact area between the chips and the tool rake face.

Mechanisms and predictive force models for machining with rake face textured cutting tools under orthogonal cutting conditions

The cutting performance and mechanisms of rake face textured carbide cutting tools in orthogonal machining of a carbon steel are investigated. Micro-grooves at 15.5 μm top width and different depth-to-width ratios are fabricated on the tool rake face using a femtosecond laser. It is found that the textures can significantly enhance the surface wettability of the cutting tools to an emulsified cutting fluid, and a fast liquid infiltration along the micro-grooves takes place. The machining tests show that cutting tools with the rake face grooves can reduce the thrust force by up to 14.68% in comparison with the untextured cutting tools, as a result of the decreased frictional force between the tool and chip. It is shown that the reduced tool-chip actual contact area due to the rake face textures and reduced tool-chip contact length due to the thinning of chip are the main reasons for this frictional force reduction. It is further found that the ploughing action between the groove edges and chip material tends to increase the frictional force while the chip material deposition to the textural structures reduces the functionality of the textures. Plausible trends of the reduction of the cutting forces with respect to the textural parameters are discussed, from which grooves in parallel to the cutting edge at 0.6 depth-to-width ratio and about 90 μm spacing are found to perform the best. A cutting force model for orthogonal machining using rake face textured cutting tools are then developed using the classical thin shear zone theory and the unified mechanics of cutting approach. The model is finally verified experimentally which shows that the model predictions agree well with the corresponding experimental data for cutting with and without a cutting fluid.

Hard turning of AISI D6 tool steel under dry, wet and cryogenic conditions: An economic investigation aimed at achieving a sustainable machining approach

The aim of this study was to encourage cleaner production processes by investigating the economic feasibility of using LN2 as a cutting fluid in the turning of quenched and tempered AISI D6 tool steel using solid PCBN inserts. For this purpose, an LN2 supply system was developed to deliver liquid nitrogen to the tool rake and flank faces. In order to measure the LN2 mass flow rate, a system based on load cells was set up. Three different LN2 flow rates (79, 51 and 21 ​L/h) were investigated. For comparison, turning tests under dry and wet conditions using a mineral-based emulsion were also performed. Nose wear (VBC) was monitored and used as one of the input parameters for an economic analysis, which was performed based on a previous study. It was concluded that the LN2 delivery system and the method used for the LN2 flow rate measurement were effective in supplying liquid nitrogen to the cutting zone in a controlled way, and liquid nitrogen at the highest flow rates provided longer cutting tool life than dry and wet conditions. Furthermore, the use of an emulsion did not increase the cutting tool life in comparison with the dry condition and machining assisted by LN2 at the lowest flow rate presented no statistical difference as compared to the wet condition in terms of production cost. Thus, based on this case study, liquid nitrogen can be considered as a sustainable alternative to the use of mineral-based emulsions, without incurring economic losses.

High Speed Machining of Inconel 718 with High Pressure Coolant Focusing on Material Structures of CBN Tools

Recently, cubic boron nitride (CBN) cutting tools and high pressure coolant (HPC) have garnered significant attention for high performance machining of difficult-to-cut materials, such as nickel-based super alloy, Inconel 718. In this study, the cutting performance of a low-CBN-content (L-CBN) cutting tool, which is known as a suitable CBN material structure for the high-speed machining of Inconel 718, is investigated under the HPC conditions. The experimetntal results show that, although crater wear is significantly suppressed as the coolant pressure increases, the combination of high cutting speed and high pressure coolant causes severe thermal cracking on the tool rake face of the L-CBN cutting tool. Hence, we evaluate the cutting performance of high-CBN-content (H-CBN) cutting tool which has smaller coefficcient of thermal expansion, compared with the L-CBN cutting tool. A series of cutting experiments shows that changing the material structure of the CBN tool effectively suppressed thermal cracking and that the H-CBN tool is a highly promising option for the high performance machining of Inconel 718.

Design, fabrication and characterization of a self-lubricated textured tool in dry machining

The manufacturing industry nowadays is facing various environmental regulations and is in the process of development of new technologies to minimize use of these lubricants during machining. One such trend is noticed in terms of surface texturing in different shapes on rake or flank face of tool which resulted in decrease in tool temperature, wear rate etc. Currently, the machining without lubricant (dry machining) is increasingly useful. This paper deals with one of the promising ways to minimize the use of cutting fluid by the development of self-lubricated tool. By this virtue, a low friction film between the working interfaces were generated during the machining. Molybdenum disulphide (MoS 2 ) powder is employed as the solid lubricant in this work. Micro textures were made on the different faces of the tool using the Epilog Fiber Laser (30Watt pulsed) and the solid lubricant (MoS 2 ) is filled in them for the purpose of self lubrication. Dry plain turning tests were conducted on Al6061-T6 alloy under different machining times and cutting speeds. The performance of textured cutting tool was investigated in terms of interfacial tool temperature and flank wear and also compared with conventional dry tool. The developed textured cutting tool with solid lubricant (MoS 2 ) generated 21–40% less cutting temperature compared to that of the dry cutting tool. This textured cutting tool also exhibited 24–35% reduction in flank wear at different cutting speeds. SEM images show significant improvement in microstructure and wear behavior of self-lubricated textured tool in comparison to the conventional dry tool.

Friction and cutting characteristics of micro-textured diamond tools fabricated with femtosecond laser

Micro-textures have been preliminarily applied to reduce the wear of metallic, ceramic, and carbide tools. However, it is still unclear which micro-textures will be effective in reducing the wears of single-crystal diamond tools. In this paper, the effectivity of micro-textures on the friction and cutting characteristics of single-crystal diamond tools were verified. Four types of micro-textures including straight grooves array, concentric circular texture, ring sequence, and mesh texture were generated on the rake face of the diamond tools with the femtosecond laser. Experimental results showed that the cutting forces and friction coefficients of the micro-textured diamond tools were greatly decreased except for concentric circular texture. Meanwhile, the cutting performances of the single-crystal diamond tools were effectively improved.

Influence of micro-structured milling cutter on the milling load and surface roughness of 6061 aluminum alloy

During the milling process, milling load and micro-vibration reduction may significantly improve the machining performance. Micro-structuring of the milling tool is one of the perspective approaches, providing force reduction and vibration suppression. In this work, two kinds of micro-structures grooved on the tool rake face have been investigated during aluminum alloy cutting: linear grooves (LG) and V-shaped grooves (VG). Milling load and the surface quality of the machined workpiece were selected to assess the milling performance of the selected tools. The results indicated that the VG milling tool showed the best performance with the reduced average milling load FX, FY, and FZ up to 9.27%, 21.98%, and 12.44% and root mean square error of FY up to 6.94% compared with a conventional milling tool. Moreover, the usage of the VG milling tool could achieve less galling wear and scratch marks on the machined surface, providing the smallest surface roughness of 0.541.

On the machinability of the Ni-30 high-temperature iron-based superalloy

Superalloys are high-performance materials which combine high tensile, creep and fatigue strength, besides good ductility, toughness and resistance to corrosion, properties that are also responsible for their low machinability. The VAT 30® alloy contains an austenitic stainless steel base with additions of chromium, nickel, titanium and aluminum, and it is mainly applied on the manufacture of valves of combustion engines, due to its advantageous characteristics. This alloy exhibits both high ductility and abrasiveness, features that may promote both attrition and abrasion wear mechanisms on the tool used to cut it. This work contains some investigations about the effect of cooling condition, tool rake angle and cutting speed on the machinability of Ni-30 alloy in terms of cutting power consumption, surface roughness and tool life, besides the tool wear mechanisms. Conventional and high-pressure coolant injected toward the tool rake face was compared, as well as negative rake angle and neutral tooling, besides two different cutting speeds. Results show that high-pressure coolant may reduce cutting power consumption and even increase the volume of material removed during tool life up to 45% in some cases, but this same influence has not been verified regarding the workpiece arithmetical mean roughness value. Negative and neutral rake angle tools did not present very different results in terms of power and roughness, but negative tools provided considerably higher volume of material removed per tool life (up to 75% in one condition). Cutting speed showed strong effect on the cutting power, as expected, but no reasonable effect on workpiece surface roughness; regarding tool life, the cutting speed increase typically reduced the volume of material removed per tool life with conventional cooling, but when high-pressure coolant was used, this effect was attenuated. Abrasion and attrition were the main tool wear mechanisms in any tested condition.

Novel Environmentally Friendly Manufacturing Method for Micro-Textured Cutting Tools

Surface texturing on cutting tools has a great influence on reducing the friction force between tool and chip interfaces. In this study, a grinding method was developed to fabricate micro-groove textures on cutting tools using a special diamond grinding wheel on the tool rake face. A comparative experiment was done using a laser and other grinding method to fabricate micro-grooves. The developed grinding method does not produce harmful gases, it is environmentally friendly, and it fabricates groove textures with high efficiency and quality. Various micro-grooves with depths of 30–90 µm, groove pitches of 0.5–1 mm, and groove angles of 30–60o were made on the rake faces of non-coated end-mill tools using the developed grinding method. Milling experiments on aluminum alloy (Al6061-T6) and tool steel (SKD11) with non-water-soluble coolant were carried out using the textured tools, and the cutting force and tool wear were investigated. In most cases, the cutting force produced by the micro-grooved tools is significantly reduced. In addition, the wear resistance of the micro-groove cutting tool is better than that of a conventional cutting tool, and there is no chipping.

Assessment of tool wear mechanisms in high-pressure jet-assisted turning process of a nickel-based superalloy

Nickel-based superalloys have many beneficial mechanical and manufacturing properties and have been used in various industries. However, the machining process and efficiency of these superalloys can be challenging due to several non-ideal factors such as undesirable chips flow, localized plastic deformation of the workpiece, and especially the tool wear. It has been shown that hybrid processes, including high-pressure jet-assisted machining (HPJAM), can be performed to improve machining efficiency. This work represents experimental methods to investigate and to quantify the effect of high-pressure jet-assisted machining on the tool wear mechanisms. The influence of variation of the turning parameters such as cutting speed, feed rate, and cutting fluid pressure on wear mechanisms was investigated along the tool rake face with respect to the position of the nozzles. An optical microscope, a scanning electron microscope (SEM), and energy-dispersive x-ray spectroscopy (EDS) analyses were used to assess the experiments. Experimental results showed that the abrasion wear was reduced, as the cutting fluid pressure was increased. The adhesion wear was minimized when an optimum fluid pressure range was used. The same behavior was observed in the development of notch wear. According to the measured parameters, the minimum notch wear occurred at the pressure of 70-bar. The tool life could be maximized by reduction of the tool wear, and the tool wear mechanisms can be better controlled if the high-pressure jet-assisted machining is performed under an optimum pressure range. Therefore, the tool wear, tool life, and material removal rates can be improved by optimizing the pressure levels and cutting parameters.

Evaluation of tool wear and cutting performance considering effects of dynamic nodes movement based on FEM simulation

An accurate estimation of tool wear morphology can provide the opportunity to investigate the influence of tool wear on cutting performance as well as reduce the overall production cost. However, tool wear prediction is still a very challenging research issue. In this paper, a novel method for simulating the actual chip formation and wear evolution thorough the 3D finite element model has been carried out. In order to improve the accuracy of simulation results, the influence of worn tool, stress and temperature distribution on wear rate are considered. Then cutting experiment has been conducted by turning AISI1045 with uncoated carbide tools to validate the accuracy of the proposed model. The comparison between experimental and simulation results show good agreement which proves the ability of the proposed model in forecasting the tool wear. The validated finite element model has been further utilized studying how the worn tool affects the cutting performance including actual cutting rake, stress distribution, cutting force and temperature. The results of this paper not only provide a clear understanding of wear evolution between tool rake face and chip, but also are meaningful to optimize tool design and cutting parameters.

Study on the effect of laser-assisted machining on tool wear based on molecular dynamics simulation

During the nanometric cutting of single crystal silicon, the wear of the diamond tool is rapid. Despite laser-assisted machining (LAM) has been used to mitigate tool wear, the specific mechanism is not clear. In this paper, molecular dynamics simulations have been successfully used to explain the effect of LAM on tool wear. The long-range carbon bond order potential (LCBOP) is used to describe the interaction of atoms in the diamond tool. The simulation results show that it has the ability to accurately simulate the graphitization of diamond. LAM enhances ductile response of silicon and reduces the cutting force. But only at the appropriate laser power, LAM will inhibit the formation of silicon carbide and mitigate tool wear. The effect of laser power on the tool rake face and clearance face is different. When the laser power is about 50 eV/ps, the wear of tool clearance face is significantly suppressed, which is attributed to the reduction of frictional resistance. When the laser power is about 150 eV/ps, the reduction in cutting forces and silicon carbide results in smaller tool wear of the rake face. At other laser powers, a large increase in chip temperature may promote tool wear to some extent. Therefore, proper laser power is necessary during LAM.

Effect of Scale and Sequence of Surface Textures on the Anti-adhesive Wear Performance of PVD Coated Tool in Dry Machining SLM-Produced Stainless Steel

During the dry post-machining processing of selective laser melting (SLM)-produced stainless steel with TiAlN coated tool, the elements of stainless steel chips can diffuse and adhere into the coated tool surface, causing serious adhesive wear. In this study, to inhibit the adhesion problem at the tool-chip interface, surface textures with different scales (micro-, nano- and micro/nano-textures) are produced on tool rake face by laser processing before and after physical vapor deposition (PVD) TiAlN coatings deposition. To investigate the cutting performance of these developed coated tools, dry machining tests of the SLM-produced stainless steel are carried out. And, the mechanical properties of textured TiAlN coatings such as the hardness, elastic modulus and critical load are also studied to explain the results from the machining tests. It can be found that the anti-adhesive wear performance of TiAlN coated tool is improved by laser surface texturing. The texture dimension significantly affects the mechanical properties and dry cutting performance of the TiAlN coated tool, and the micro/nano-textures are found to be optimum. Meanwhile, the sequence of surface textures also has an effect on the wear performance of the developed TiAlN coated tools. In the experiment, laser surface texturing before coatings is effective in acting as a barrier against flaking of the TiAlN film, providing a higher active surface for the subsequent TiAlN coatings and presenting a higher compressive residual stress. Thus, the developed cutting tool which is textured before TiAlN coatings deposition presents a milder wear compared to the developed one which is textured after TiAlN coatings deposition.

Influence of radial rake angle and cutting conditions on friction during end milling of Nimonic 263

In machining processes, the friction and frictional stress formation along the interface between the chip and the tool rake face give rise to energy consumption, tool wear, and failure. This study aims to investigate the influence of tool nomenclature (radial rake angle) and cutting conditions (spindle speed and table feed velocity) on the impediment of friction and frictional stress in the perspective of equivalent pressure coefficients during end milling process, and additionally, the comparative study has been made. The experimental outcome clearly indicates that the machining parameter and tool nomenclature have significant effects on frictional stress impediment under pure sliding condition. Among these, tool nomenclature has higher and significant beneficial impact on the obstruction of frictional stress formation, and it is also stated that the cutting force and friction decreases, when the radial rake angle of cutter decreases when the helix angle and the positive axial rake angle is constant.