Tool-chip Contact Research Articles

The Research on Tool-Chip Contact Length for Cutting Superalloy under High Pressure Cooling

High pressure cooling is a new cooling technology, which provides a certain technical support for cutting superalloy. In this paper, the theoretical model of the acting area and force of the coolant under different pressures were established. A theoretical model of the tool-chip contact length in cutting superalloy under high pressure cooling was established by the theory of material mechanics. Through theoretical research and simulation analysis, it is concluded that high pressure coolant can reduce the tool-chip contact length, and with the increase of coolant pressure, the contact length further decreases.

Machinability analysis of Titanium 64 using ultrasonic vibration and vegetable oil

ABSTRACT Industries have been pursuing a competent machining strategy that fulfills the necessity of sustainability without deteriorating tool wear or final product quality of components made from difficult-to-cut material Titanium 64. This article attempts a combination ultrasonic vibration with vegetable oil-based cutting fluid (VCF), to increases the tool life and machinability of Titanium 64. In-house developed Ultrasonic-assisted turning (UAT) setup for vibration, and emulsion of 10% Canola oil for cooling, are used. The machinability in respect of cutting and feed force, tool-chip contact length, and flank and crater wear, are examined. As a result, the UAT under VCF offers a reduction in tool-chip contact length by 12–45%, cutting force by 10–25%, and feed force by 20–40%. Moreover, ultrasonic-assisted turning using vegetable oil-based cutting fluid also decreases the adhesion and abrasion wear from the rake face, which is obvious in the conventional turning process of Titanium 64.

A Numerical Model for Predicting the Effect of Tool Nose Radius on Machining Process Performance during Orthogonal Cutting of AISI 1045 Steel.

This paper presents the development of a numerical model for predicting and studying the effects of tool nose geometries and its interactions with cutting parameters during orthogonal cutting of AISI 1045 steel. The process performance characteristics studied were cutting temperature, effective stress, cutting forces and tool wear. The cutting simulations were done using the commercial DEFORM-2D R V 11.3 software, based on the finite element method (FEM). The cutting tool used had a round nose with various nose radii (0.01–0.9 mm), while the machining parameters tested were the feed rate (0.1–0.3 mm/rev), the cutting speed (100–500 m/min) and the rake angle (–5° to +10°). The interactions between the tool nose radius and the cutting parameters (speed, feed) were found to affect mostly the cutting stress and, slightly, the tool wear rate. These interactions did not much influence the cutting temperature, that was found to be high when the tool nose radius and/or the cutting speed were high. The maximum temperature was found to occur at the middle of the tool-chip contact length and at the interaction of nose radius and flank face of the tool. Except for some fluctuations, there was no significant difference in tool wear rate between small and large nose radius scales.

Determination of the Tool-Chip Contact Length for the Cutting Processes.

The thermomechanical interaction of the tool with the chip in the most loaded secondary cutting zone depends on the contact length of the tool rake face with the chip. Experimental studies of the dependency of the contact length on the cutting speed, the undeformed chip thickness, and the tool rake angle, performed by the optical method, are used for comparison with the contact length obtained by the FE modeling of the orthogonal cutting process. To determine the parameters of the constitutive Johnson–Cook equation, which serves as a material model of the FE cutting model that has a predominant influence on the contact length, a software-implemented algorithm was developed. This algorithm is based on determining the generalized parameters of the constitutive equation through finding the intersection of these parameter sets. The plurality intersection of the parameter sets of the constitutive equation is determined by means of the design of experiments and refined by subsequent multiple iterations. The comparison of the contact length values, obtained by simulating the cutting process using the generalized parameters of the constitutive equation as a material model with their experimental values, does not exceed 12% for a wide range of cutting speeds and depths of cut, as well as for the tool rake angle.

Tool-chip contact and chip formation in dry finish-machining of austempered ductile iron

Straight dry finish-turning of a structural grade of austempered ductile iron (ADI) using cBN-TiC cutting tools was analysed. The influence of cutting speed on the characteristics of the tool-chip (TC) contact and chip-formation processes was the focus of this research. Experimental and analytical procedures were used in this respect. An approach to estimate the TC sticking contact length and TC stress distribution index was built to complement them. The feed rate, nominal rake angle, and depth-of-cut were kept at 50 μm rev−1, −26°, and 200 μm, respectively. The cutting speed was varied in the range of 50–800 m min−1. Strain-rate effects on the shear flow stress of structural ADI overpower their antagonist temperature impacts drastically in primary deformation zones (PDZs) and gradually in secondary deformation ones (SDZs). Accordingly, TC sliding-friction coefficient rises with the mean TC homologous temperature. The mean total energy brackets nearly match the range of specific cutting resistance for grinding of cast‑irons, related to the uncut-chip thickness of 14.23 μm. The levels of TC equivalent contact-stresses and mean TC contact temperature vividly reveal the vulnerability of cBN-TiC cutting-inserts edges for cutting speeds past 200 m min−1. The distribution index of TC contact stresses settled between 0.96 and 0.58. SDZPDZ softening degree decreased with cutting speed, landing between 76 and ~0%. Two bordering machining regimes, features of abrupt variations of local and global characteristics of the TC contact and chip-formation processes, emerged from the evolution of chip morphology with cutting speed: I: 50–150 m min−1, II: 200–800 m min−1. The pairing of these characteristics made it possible to blend them effectively. A better-informed procedure to select feed rate and cutting speed was then suggested.

Machinability investigation and sustainability analysis of high-pressure coolant assisted turning of the nickel-based superalloy Inconel 718

In recent years, issues related to eco-friendly machining have received more and more attention, leading to the development of new cooling/lubrication techniques. Herein, the paper investigates the effect of high-pressure coolant (HPC) supply on machining performance of Inconel 718 and compare with conventional flood cooling. Significant improvement in tool life, tool wear, tool-chip contact length, material removal volume, and cutting forces have been observed from the outcomes of HPC cooling condition. Moreover, in order to study the environmental impact of machining Inconel 718, a carbon emissions model was established and analyzed for high-pressure and flood cooling conditions, taking into account the carbon emissions from energy, material, cutting tool, and cooling/lubrication fluid. HPC assisted machining was revealed to be better as it makes possible a reduction in overall carbon emissions at higher cutting speeds. In addition, economic analysis for both cutting environments was also carried out. Significant improvement in reduction of the overall machining cost was observed under HPC conditions, especially at higher cutting speeds. In a nutshell, the findings revealed better performance of HPC assisted machining, with regard to machinability, environmental, and economic issues.

Evaluation of methods for measuring tool-chip contact length in wet machining using different approaches (microtextured tool, in-situ visualization and restricted contact tool)

The contact length is one of the most important factors to evaluate the chip formation process and the mechanical loads in metal cutting. Over the years, several methods to identify the contact length were developed. However, especially for wet cutting processes the determination of the contact length is still challenging. In this paper, three methods to identify the contact length for dry and wet processes in cutting of Ti6Al4V and AISI4140 + QT are presented, discussed and analyzed. The first approach uses tools with a microtextured rake face. By evaluating the microstructures on the chip, a new method to identify the contact length is established. The second approach applies high speed recordings to identify the contact length. The challenge is thereby the application of high-speed recordings under wet conditions. In the third approach, tools with restricted contact length are used. It is shown that with all three methods the contact length is reduced using metal working fluid.

Effects of submerged convective cooling in the turning of AZ31 magnesium alloy for tool temperature and wear improvement

Low melting point and material adhesion are associated challenges of magnesium alloy, leading to extreme built-up edge (BUE) and built-up layer (BUL) formations during machining process. Dry machining is favorable for machining magnesium alloy. However, this strategy inflicts excessive adhesive wear on the cutting tool. Therefore, this current work focuses on application of an innovative cooling technique, known as submerged convective cooling (SCC) for the turning of AZ31 magnesium alloy. Prior to cutting experiment, a computational fluid dynamics (CFD) simulation was conducted to evaluate internal structure of cooling module. Based on the CFD simulation, a small inlet/outlet diameter of 3 mm significantly contributed to the reduction of the tool temperature, due to high heat transfer coefficient of cooling fluid in the SCC. From the experimental results obtained, it was evident that SCC at high cooling water flow rate of 130 mL/min effectively reduced the tool temperature, chip temperature, and tool-chip contact length by approximately 50, 8, and 28%, respectively. Consequently, it improved the surface roughness by 37%, when compared with the dry cutting condition. Finally, both BUE and BUL were observed in dry and SCC conditions, but the severity of these wear mechanisms improved or decreased remarkably under SCC conditions.

Modeling and analysis of tool-chip contact model during quasi-intermittent vibration assisted swing cutting based on two-zone theory

Modeling and analysis of tool-chip contact model during quasi-intermittent vibration assisted swing cutting based on two-zone theory

Characterization of material flow mechanism for chamfered tools utilizing coupled slip-line-slab method

Sintered carbide tools with their edge chamfered have superior resistance against brittle fracture of the main edge. Such advantage is mainly attributed to the formed built-up edge (BUE) anterior to the chamfer face. However, as the cutting process, certain materials including cracked BUE in that vicinity will inevitably flow aside along the chamfer face, which eventually causes severe notch wear and lateral burr formation. Given this deficiency, both theoretical and experimental works were carried out for the cutting process with chamfered tools in the current study. In the theoretical part, the material flow mechanism was analyzed and modeled by classifying the process into three typical modes concerning specific chip-tool contact patterns, for which three sets of modified slip-line solutions were developed accordingly. Furthermore, a unique solution to the three-dimensional (3-D) material flow status was achieved by combining slip-line theory with the slab method. On this basis, the effects of tool preparation factors, i.e. chamfer width, chamfer angle, tool-workpiece friction coefficient and rake angle, on the BUE extrusion were discussed in detail. The results indicate that with proper chamfered edge design, accumulative BUE will be flowing in an optimal condition. In this case, the lateral burrs were found effectively restrained as had been evidenced by conducting extensive orthogonal cutting experiments with chamfered tools. By comparing with released models and experimental measurements, the present model yields more accurate predictions of material flow states. These findings of present study can contribute to the optimal design of cutting tools with chamfered edge.

Combined lubrication of surface texturing and copper covering for broaching tool

Broaching is widely used in the aerospace field owing to its high efficiency and heavy load. However, heavy-load cutting causes intense squeezing and friction in the tool-chip contact area, resulting in a lack of lubrication. Therefore, three textures (i.e., micro-pit, stripe, mesh) are prepared on the rake face of broaching tool with a laser processing technique to improve cutting performance. Afterward, textures are covered with copper using the reciprocating rotational friction to enhance the wettability and heat dissipation capacity of the broaching tool. Experiments approve that striped textures covered with copper reduce the cutting force by 14.6% and the cutting temperature decreases from 90.13 to 76.9 ℃, compared with non-textured cutting teeth. Obtained results indicate that the wettability of cutting fluid on the tool surface is significantly improved due to the capillary force of micro-pores generated by the copper covering, especially in the direction to the cutting edge. Furthermore, the copper debris absorbs heat quickly in the cutting areas and is subsequently taken away by chips and cutting fluids, thereby reducing the cutting temperature.

Turning characteristics of titanium alloy Ti-6Al-4V with high-pressure cutting fluid

This study investigates the effect of high-pressure cutting fluid on the turning characteristics of Ti-6Al-4V alloy. A noncoated carbide tool was used to measure the cutting temperature using a tool-work thermocouple technique, and the cutting characteristics were evaluated with respect to the cutting temperature, chip breakability, and tool wear. Furthermore, the viability of TiAlN/AlCr2O3-coated tool was examined. The coolant jet when placed towards the cutting zone on the rake face is effective in reducing the cutting temperature because of the reduction in the chip-tool contact length. Based on this result, tools with a textured rake face were examined.

An analytical model for the optimized design of micro-textured cutting tools

Proper design of micro-textured cutting tools is an effective strategy to improve the machining performance by reducing the tool-chip contact length and the resultant friction and thus improving tool life and workpiece surface integrity. In this paper, an Oxely-based analytical model is developed to optimize micro-textured cutting tool design(s) which eliminate the occurrence of derivative cutting. The model accommodates any workpiece material, tool geometry, and machining parameter. The model was validated by orthogonal cutting of AISI 1045 steel tubes. The results show that the optimum micro-texture design eliminates derivative cutting and lowers forces compared to the non-textured cutting tool.

On the tribological and machining performance of laser textured sintered carbide cutting tools in turning of Al2024

This study investigates the performance of geometrically defined dimple and groove textures in the turning of Al2024. On-machine testing using combinations of periodic SEM imaging and cutting force capture were used for wear assessments of the textured surfaces and to provide input data for tribology testing. Tribometer investigations were conducted to determine the influences of surface textures on elastohydrodynamic lubrication, influenced by tool-chip contact pressure and entrainment area. The study has shown that both dimple and groove textures can reduce surface friction by influencing mixed and hydrodynamic contact, resulting in reductions of cutting forces.

Cutting force & thermal analysis during turning using Ansys

In metal cutting, the magnitude of the cutting forces and temperature at various interfaces is the function of the cutting process variables. These cutting process variables directly affect production. Therefore, more research on this topic and further development will lead to improved production. Experimental work was conducted under dry machining with heat-treated 4140 Alloy Steel workpiece and the cutting tool was Cast Steel Silver Brazed Carbide were used under turning process. In this experimentation, during the machining the cutting forces were measured using Tool-Lathe Sharp Techno Dynamometer and the temperature measurement was done employing two techniques that were K-Type Thermocouple for the tool temperature and Infrared Thermometer for the tool chip contact area temperature. In this research, Finite Element Analysis (FEA) methodology was used, with cutting forces and temperatures at the different points of the cutting tool as an input. Model of the Single Point Cutting Tool (SPCT) was generated using Solid Works software and the analysis was done in Ansys (Workbench) software. The Ansys software analyzed the Single Point Cutting Tool (SPCT) model by FEA and results obtained are discussed in this study.

Development of Protruded Textured HSS Cutting Tool and Study of Its Impact on Cutting Performance during Dry Turning of Al 6063 Alloy

ABSTRACT Machining with the textured cutting tool is an emerging sustainable method to improve the cutting performance of the tool. In this work, an attempt has been made to improve the cutting performance of HSS cutting tool by fabricating the protruded surface textures on the rake surface of HSS cutting tool. A triangular-shape protruded textures were fabricated on HSS cutting tool by radium masking followed by chemical etching process (CEP). Protruded textured (PT) cutting tools are used in the dry machining of aluminium 6063 alloy, and these tools were compared with the cutting performance of non-textured (NT) cutting tool. Experimental results showed that protruded textured (PT) tool has significantly impact on reduction of chip-tool tool contact area it leads to improved the cutting performance as compared to NT cutting tool.

Enhancing Wear Resistance and Cutting Performance of a Long-Life Micro-Groove Tool in Turning AISI 201

Tool-chip friction increases cutting temperature, aggravates tool wear, and shortens the service life of cutting tools. A micro-groove design of the rake face can improve the wear performance of the tool. In this study, we used the finite element simulation “Deform” to obtain the temperature field distribution of the tool rake face. The size of the micro-groove was determined by selecting a suitable temperature field combined with the characteristics of tool–chip flow in the cutting process, and the tool was prepared using powder metallurgy. The three-direction cutting forces and tool tip temperature were obtained by a cutting test. Compared with the original turning tool, the cutting force and cutting temperature of the micro-groove tool were reduced by more than 20%, the friction coefficient was reduced by more than 14%, the sliding energy was reduced and the shear energy was greatly decreased. According to the analysis of tool wear by SEM (scanning electron microscope) and EDS (energy dispersive X-ray spectroscopy), the crater wear, adhesive wear and oxidation wear of the micro-groove tool were lower than those of the original turning tool. In particular, the change in the crater wear area on the rake face of the original tool and the micro-groove tool was consistent with the cutting temperature and the wear width of the flank face. On the whole, the crater wear area and the change rate of the crater wear area of the micro-groove tool were smaller. Due to the proper microgroove structure of the rake face, the tool-chip contact area decreased, and the second rake angle of the tool became larger. Hence, the tool-chip friction, cutting forces, cutting energy consumption were reduced, tool wear was improved, and the service life of the micro-groove tool was five times longer than that of the original tool.

Cutting Force Prediction Model for Elliptical Vibration Cutting SiCp/Al Based on Three-Phase Friction Theory

The friction behavior in the tool-chip interface is an essential issue in aluminum matrix composite material (AMCM) turning operations. Compared with conventional cutting, the elliptical vibration (EVC) cutting AMCM has attractive advantages, such as low friction, small cutting forces, etc. However, the friction mechanism of the EVC cutting AMCM is still inadequate, especially the model for cutting forces analyzing and predicting, which hinders the application of EVC in the processing of AMCM. In this paper, a cutting force prediction model for EVC cutting SiCp/Al is established, which is based on the three-phase friction (TPF) theory. The friction components are evaluated and predicted at the tool-chip interface (TCI), tool-particle interface (TPI) and tool-matrix (TMI), respectively. In addition, the tool-chip contact length and SiC particle volume fraction were defined strictly and the coefficient of friction was predicted. Based on the Johnson-Cook constitutive model, the experiment was conducted on SiCp/Al. The cutting speed and tool-chip contact length were used as input parameters of the friction model, and the dynamic changes of cutting force and stress distribution were analyzed. The results shown that when cutting speed reaches 574 m/min, the tool-chip contact length decreases to 0.378 mm. When the cutting speed exceeds 658 m/min, the cutting force decreases to a minimum of 214.9 N and remains stable. In addition, compared with conventional cutting, the proposed prediction model can effectively reduce the cutting force.

High-pressure flank cooling and chip morphology in turning Alloy 718

The use of cutting fluids is commonly considered a necessity while machining Heat Resistant Super Alloys (HRSA). Specifically, cutting fluids applied under high-pressure, which for many decades have been the solution for the most demanding applications. The results might be diverse and vary between applications, but typically leads to improved tool life, enhanced chip breakability, lower temperature in the cutting zone and better surface quality of the finished product. The available high-pressure cutting fluid delivery systems are usually designed with the intention to improve the cutting fluid penetration at the vicinity of the cutting edge on the rake face side of the insert. However, there has been limited interest in investigating high-pressure cutting fluid applied to its flank face. Both specifically and in combination with cutting fluid directed to the rake face. In this study, the focus has been to investigate the chip formation process during the turning of Alloy 718 (Inconel 718). Particularly, for a defined turning operation where high-pressure cutting fluid is applied to the flank side as well as the rake side of an uncoated carbide insert. Several combinations of pressure levels and jet directions were investigated. The corresponding effects on the tool-chip contact zone and chip characteristics were studied for two cutting speeds. The results of the investigation showed a substantial improvement in lowering the tool-chip contact area at a rake pressure of 16 MPa. At which pressure, additional cutting fluid applied to the flank at a moderate pressure of 8 MPa had no dominant effect on chip formation (chip break). However, flank cooling of the cutting zone supports chip segmentation and thus indirectly chip breakability. For cutting fluid applied to the rake side at a more moderate pressure of 8 MPa, more prominent effects on the insert became apparent when additional cutting fluid was applied to the flank side. This was particularly noticeable when cutting fluid was directed towards the flank side of the insert at the same pressure level as the cutting fluid applied towards its rake face. The additional thermal transfer was seen to have a significant effect on the material deformation phenomena in the primary shear zone (lowering shear angle) as well as the sliding and sticking conditions of the tool-chip interface. Based on the evidence from this study, it can be concluded that cutting fluid applied towards the flank side of the insert has a significant impact on the cutting process. In particular, if applied in combination with a rake pressure at a similar level, in this case, 8 MPa.

Evaluation on the performance of hybrid textured coated tool under conventional cooling environment

During the process of cutting aluminum alloy with WC/Co coated tools, severe adhesion and wear exist on the tool-chip contact interface, which are the major factors leading to failure of cutting tools. To address this problem and extend the service life of cutting tools, this study introduced surface textures into coated tools, trying to integrate the anti-friction properties of micro-textures with the wear resistance properties of coating to improve tribological characteristics of tools surface. Firstly, hybrid texture consisting of micro-scale pits and micro-scale grooves were fabricated on the rake surface close to the main cutting edge of carbide tools by picosecond laser. Subsequently, the textured tools were deposited with hard-coating CrAlN via physical vapor deposition (PVD) technology, and the hybrid textured CrAlN coated tool (MPG-T) was obtained eventually. Other texture combinations included micro-scale pits and micro-scale grooves distributed in the tool-chip contact zone. Wet cutting experiments were carried out with these prepared tools. Results showed that MPG-T tool performed better in cutting forces, friction coefficient, tool adhesion and wear on the rake face and the flank face, chip morphology compared with micro-scale pitted coated tool (MP-T), micro-scale grooved (MG-T) and conventional coated tool (CCT). Moreover, the corresponding synergistic mechanisms of hybrid texture and coating were proposed. It’s suggested that applying the results to actual industries can enhance the performance of coated tools in machining of 6061 aluminum alloy.