Cutting Edge Radius Research Articles

Effect of cutting edge radius on end milling Ti–6Al–4V under minimum quantity cooling lubrication – Chip morphology and surface integrity study

The effect of cutting edge radius (30–55 μm) during milling Ti–6Al–4V under minimum quantity cooling lubrication (MQCL) conditions is studied. A trial study is conducted to compare the performance of dry, wet, and MQCL using unprepared tools with edge radius of 30 μm alone. Subsequently, inserts having initial radius of 30 μm are prepared to 40–55 μm radius using drag finishing and milling of Ti–6Al–4V under MQCL is studied for different edge radii. Rounded edge tools are found to produce thinner and more curvilinear chips resulting in easier chip removal from the machining zone. The chip thickness and curl radius were up to 54% and 47% lower for the larger edge radius tools as compared to the 30 μm edge radius tool. This improves the penetration of the MQCL aerosol jet into the cutting zone thus producing better tribological results. The better penetration of MQCL aerosol into the cutting zone for larger edge radius tools results in lowering the resultant process forces (up to 16%), tool-chip interface temperature (15%), tool wear (40%) and surface roughness (30%) for the 48 μm radius tool as compared to the unprepared (30 μm) tool. There is deterioration in process forces, tool wear and surface integrity for the 55 μm tool possibly suggesting the existence of an optimum edge radius closer to 48 μm.

Study about the chip formation in the turning process using the finite element analysis

At this time, there is a significant interest in the chip shape and formation at the international level, an issue studied based on mathematical calculations, experiments, and finite element analysis. The analysis of the chip formation process showed that the thickness of the undetached chip also varies according to the rake angle of the cutting tool, and using 3D models to analyze the chip formation process demonstrates this fact. Following the research, a study was conducted in which an analysis of the chip morphology is presented. Using Deform 2D application, a finite element simulation - a comparative analysis of the chip formation was performed when the value of the clearance angle varies. The increasing variety of cutting radius values has an influence on the way the chips are formed in terms of thickness, which generate differences in its shape. Following the study, a series of conclusions and own findings emerged that with the increase of the cutting-edge radius, the stress distribution is radial over a greater area of the part, reason for which the deformation of the chip is smaller. Arguments have also been made on distribution of the temperature, which is directly influenced by the shape of the tool, influencing the temperature of the generated chip. The results also show that with the increase of the cutting-edge radius of the tool, there is a tendency for the detached chip to settle.

An improved cutting force model in micro-milling considering the comprehensive effect of tool runout, size effect, and tool wear

Tool runout, cutting edge radius-size effect, and tool wear have significant impacts on the cutting force of micro-milling. In order to predict the micro-milling force and the related cutting performance, it is necessary to establish a cutting force model including tool runout, cutting edge radius, and tool wear. In this study, an instantaneous uncut chip thickness (IUCT) model considering tool runout, a nonlinear shear/ploughing coefficient model including cutting-edge radius, and a friction force coefficient model embedded with flank wear width are respectively constructed. By integrating the IUCT, the nonlinear shear/ploughing coefficient and the friction force coefficient, a comprehensive micro-milling force model including tool runout, cutting edge radius, and tool wear is derived. Experiment results show that the proposed comprehensive model is efficient to predict the nonlinear cutting force of micro-milling with variable tool runout, cutting edge radius, and tool wear.

Wear characteristics of the pointed diamond tool in ultraprecision and micro cutting of Al 6061 V-grooves

Pointed diamond tool has been widely used in ultraprecision manufacturing of V-grooves. This article provides a wear law and wear characteristics of pointed diamond tool during V-grooves machining with the consideration of the cutting stress and the strength of diamond, which could be used to estimate the tool wear state and control the V-grooves machining quality. In this research, the model of cutting stress distribution and cutting force in V-grooves machining are established, which indicate that the maximum normal stress is independent on the cutting depth. Then, the tool tip fracture condition and cutting edge wear law of pointed diamond tool are further explored. The obtained law and experiments results shows that the tool wear is reflected in the cutting edge radius increasing while the wear rate is high at the beginning and then decreases gradually. Besides, the wear characteristic of the tool tip is different from the side cutting edge due to the diamond strength anisotropy. Raman spectra analysis indicates the wear mechanism of the tool is mechanical friction wear in machining of Al 6061 V-grooves.

Numerical Modeling of the Effect of Cutting-Edge Radius on Cutting Force and Stress Concentration during Machining.

Cutting is the primary method of material removal, and the quality of machined parts depends on the geometry of cutting tools. In this paper, a new cutting force coefficient model is established, revealing the influence of cutting-edge radius on the cutting process. The effects of cutting-edge radius on the shear angle and cutting force components are analyzed by finite element simulations. A series of simulations is conducted, and the results show that with increased cutting-edge radius, the shear angle decreases nonlinearly, and the cutting force increases gradually. Additionally, the growth rate of the feed force caused by increasing the cutting-edge radius is higher than that of the tangential force. Furthermore, the stress concentration area of the machined surface extends from the surface to the subsurface as the cutting-edge radius increases. The results of this research show that changing the cutting edge affects the cutting force component, shear angle, and stress concentration range during the cutting process. These results provide a theoretical reference for predicting the residual stress in parts.

Geometry, Structure and Surface Quality of a Maraging Steel Milling Cutter Printed by Direct Metal Laser Melting.

This article considers the use of additive manufacturing to produce cutting tools for various machining operations, especially turning, milling, and drilling. The right geometry and material of the tool as well as coatings applied on cutting edges are crucial as they improve the life and performance of the tool. The study described here focused on a four-flute end mill made of maraging steel 1.2709 using a Concept Laser M2 Cusing Direct Metal Laser Melting (DMLM) machine. Before the printed tool was first used, it was examined to determine its dimensional and geometric accuracy, surface roughness, and surface structure. The measurement data showed that the tool required machining, e.g., grinding, to improve its geometry because the total runout of the shank and the cutting edge radius were too high, amounting to 120 μm and 217 μm, respectively. The cutting edges were sharpened to obtain a fully functional cutting tool ready to perform milling operations. The study aimed to check the dimensional and geometric accuracy of the 3D printed milling cutter and determine the optimal machining allowance for its finishing.

Method for an Effective Selection of Tools and Cutting Conditions during Precise Turning of Non-Alloy Quality Steel C45.

The paper presents a constructing methodology for a modern approach to tools selection and solving the problem of assigning optimal cutting parameters for specific production conditions. The mathematical formulation determining the extreme values of the technological process optimality criteria is obtained. A system of technical and economic quality indicators for cutting tools is proposed. This system allows principles’ implementation of decentralization and interoperability “Industry 4.0” via finite element modeling of the cutting process based on solving the problem of orthogonal free cutting modeling. The proposed methodology further usage is possible by creating a standardized database on the parameters of the tool: the adhesive component of the friction cutting coefficient for processing of a specific pair of cutting and tool materials (or tool coating material) and the impacts of the cutting-edge radius on cutting efficiency of a particular material.

Multi-objective optimization of edge quality and surface integrity when wire electrical discharge machining of polycrystalline diamonds in cutting tool manufacture

This work presents an energy-saving approach to the single-pass wire electrical discharge machining (WEDM) of polycrystalline diamond with no degradation in edge geometry or surface integrity in cutting tool manufacture. The proposed boundary conditions and discharging wavelets enable the least number of pulse-off durations to effectively recover the electrical potential for the extended discharging action and the successively energy saving via a secondary MOSFET circuit. Secondly, the determined pulse-off durations could sufficiently improve the effectiveness of the Joule heat model which did not consider the extrinsic interference from the removed materials in the discharging gap. Full factorial design experiments were performed to validate the effects of the operating parameters on the material removal rate, surface roughness, cutting edge radius, and surface waviness in single-pass WEDM for the shaping of diamond cutting tools. Precision levels in the fitting of analytic models to experiment results were presented. Linear algebra was introduced to evaluate the selection of operating parameter combinations aimed at optimizing of observations with adjustable weightings. Thermal induced defects and alterations in the microstructures were reported and discussed. The proposed ready-to-use diamond cutting tools present a good balance between energy savings and appreciable outcomes.

On deformation characterisation of machined surfaces and machining-induced white layers in a milled titanium alloy

Machining-induced white layers and severely deformed layers are undesirable surface integrity features which can be formed when machining high-strength aerospace alloys. An orthogonal milling process has been designed and performed to assess the impact of cutting speeds, tool wear, cutting edge radius and climb vs conventional milling on white layer formation and plastic strain distribution. The plastic deformation in the machined surface associated with the formation of white layers in Ti-6Al-4V has been quantified using micro-grids of different length scales printed using the electron beam lithography technique. It was found that white layers formed via the severe plastic deformation mechanism, at equivalent plastic strain values in excess of 1.2 and in regions of the cutting arc with the instantaneous chip thickness of less than the cutting-edge radius and ploughing and rubbing being the dominant mechanisms. The results indicated that the magnitude of the measured strains and the depth of plastically deformed material was greater at lower cutting speeds, during climb milling and when machining with a larger cutting edge radius and tool flank wear land.

Abaqus-Based Optimization Study of Cutting TC4 Tool Parameters for Micro-Weaving Tools

To reduce the machining difficulty of TC4, reduce the main cutting force in the cutting process, reduce the temperature in the cutting area and extend the cutting tool life. Three micro-weaving configurations of rectangular flutes, semi-circular flutes, and triangular flutes were designed on the rake face of the tool, and the rake angle, relief angle, and cutting edge radius of the semi-circular flutes were set at three levels, and the finite element method was used to find the micro-weaving configuration of the tool with the minimum main cutting force and the optimal combination of tool geometry parameters. The results show that under the same cutting conditions, the semicircular fluted micro-weaving tool has the lowest main cutting force among the three micro-weaving profiles; the semicircular fluted micro-weaving tool has 0 °rake angles, 15 °relief angles, and 0.03 mm cutting edge radius, which has the lowest main cutting force.

Investigation of residual stresses and workpiece distortion during high-feed milling of slender stainless steel components

In high-feed milling, the workpiece surface is subjected to high thermo-mechanical loads, which leads to excessive changes in residual stresses and thus affects the quality of the product. In this work, the influence of tool geometry and cutting speed on the residual stress state and the resulting workpiece distortion was investigated. Machining tests were performed by face milling of slender parts made of low sulfur stainless steel X2CrNiMo17-12-2. The results showed that the macro-geometry of the tool has a major influence on the surface topography and residual stresses. The cutting edge radii have barely any influence on the residual stresses under the conditions investigated.

Dry etching of single-point cutting tool made of nano-polycrystalline diamond using oxygen plasma (Shapeable cutting edge radius)

Dry etching of single-point cutting tool made of nano-polycrystalline diamond using oxygen plasma (Shapeable cutting edge radius)

A model of micro-milling cutting forces based on micro-cutting experiments including tool eccentricity and deflection

In this study, a model of micro-milling cutting forces based on elementary cutting experiments is developed. Elementary cutting tests were used to identify the parameters of a new model that includes the uncut chip thickness and the effect of the cutting edge radius. This model assumes a straight cutting edge and a rigid cutting tool and is divided into two terms that represent the ploughing and shearing regimes. The complex shape of the cutting edge of the micro-end-mill is decomposed into linear elementary edges to which the force model can be applied. The uncut chip thickness during tool rotation includes the tool path deviation due to tool run-out and deflection. Micro-milling experiments were performed using a micro-end-mill with the same cutting edge geometry as the tool used in elementary cutting experiments on AISI 6F7 steel. Comparisons between the force model and the experimental results show a good correlation. This model can be extended to a ball-nose micro-end-mill to consider a wide range of operations and can be used to predict and avoid machining errors due to deflection and even tool breakage.

Effect of cutting edge radius on cutting force and surface roughness in machining of Ti-6Al-4V

This study aims to investigate the effect of cutting edge radius on surface roughness in orthogonal cutting of Ti6Al4V based on numerical simulation. A finite element model is established to model the machining-induced surface roughness using a Coupled Eulerian-Lagrangian (CEL) method. The CEL method can be used to simulate the elastic recovery on machined surface, and the surface topography in cutting speed direction can be achieved. Then, the impact of mesh size on numerical force and surface morphology is discussed, and it is concluded that fine mesh has better performance in force and surface roughness prediction. The significant influence of edge radius on feed force and surface roughness can be noted through simulations with fine mesh, that is, a larger edge radius can provide larger feed force and rougher machined surface. Finally, the effectiveness and correctness of proposed model are validated by orthogonal cutting experiments of Ti6Al4V.

Investigating flank face friction during precision micro cutting of commercially pure titanium via plunging tests with diamond grooving tools

This study investigates flank face friction while micro machining commercially pure titanium (cp-Ti grade 2) work material considering size effects. It is important to understand friction phenomena at the tool flank and work material surface since they affect the surface integrity of the machined parts. A single crystal diamond grooving tool is used in machining experiments to reduce the influence of cutting edge radius. In addition, plunging type of cutting experiments were performed to investigate the influence of flank face contact on the machined surface. A friction model which is based on work and tool material properties is proposed to model the contribution of adhesion and deformation of the flank face coefficient of friction. The results show that for the cp-Ti and diamond tool pair, adhesion seems to be the dominant model of friction and also contributes to the size effect. The deformation friction becomes more dominant during the chip formation stage. When cutting edge effect is eliminated, the influences of flank and rake face friction on the size effect are shown.

Cutting edge radius effect on the surface integrity of orthogonal turned aluminium alloy Al6082 with different initial microstructure

In the present study, the combined effect of initial microstructure and relative tool sharpness (RTS) on the surface integrity of aluminium(Al6082) alloy has been investigated. Orthogonal turning is carried out on as-received and heat-treated specimen with group of edge radiused tools. Surface roughness and micro hardness have been evaluated with respect to number of turns for varying RTS value. Results indicate that the workpiece material adhesion on the tool has significantly influenced the surface roughness. In addition, below the critical RTS, the surface integrity is greatly influenced by the grain size of the material.

Machining-induced surface integrity in titanium alloy Ti-6Al-4V: An investigation of cutting edge radius and cooling/lubricating strategies

Enhanced surface integrity can increase the service life and functional performance in machined components, including the strength and fatigue life of machined parts. To study the influence of cutting edge radii and cooling/lubricating conditions on surface integrity, in this work variable cutting edge radii (less than 5 μm, 28 μm and 50 μm) and a range of cooling/lubrication conditions (Dry, MQL, LN2, Hybrid with LN2 and MQL) were applied in orthogonal cutting of Ti-6Al-4V alloy. Experimental analysis revealed that ploughing effects, which increase with increasing cutting-edge radii, and result in material being compressed into the machined surface, lead to an increase in thrust force, drive the evolution of subsurface microstructure at the cross-section which is normal to the direction of cutting speed. No obvious grain refinement layer was observed while utilizing the sharp cutting edge (<5 μm). At larger edge radii (28 and 50 μm), the thickness of grain refinement layer caused by severe plastic deformation (SPD) increased significantly. The residual stresses analysis was carried out based on investigations of selected experimental conditions. In machining with larger cutting edge radii and hybrid cooling, significant increases in the magnitude and depth of machining-induced compressive residual stress fields were also observed. Additionally, surface hardness also increased slightly with increasing cutting edge radius. Machining with cryogenic cooling (LN2) generated thinner deformation layers and larger deformation gradients, due to higher deformation stress and lower fracture strain at lower temperature conditions. Moreover, the rapid transfer heat from the cutting zone mitigated the tensile stress generating mechanisms, typically associated machining, allowing for mechanical ploughing effects to become dominant in the near-surface region of the machined workpieces.

Experimental and Numerical Studies of Tool Wear Processes in the Nibbling Process.

The work concerns an analysis of the wear mechanisms of punches in the nibbling process. The nibbling process is the multiple punching of holes or external contours using circular punches, the diameter of which is much smaller than the size of the punched shapes. Analytical, numerical and experimental studies were carried out. In the analytical solution, formulas for determining the pressures in the contact zone were developed, thus enabling a simple estimation of the designed nibbling tools. In numerical studies, the influence of the punch rounding radius on the fatigue wear was investigated. It has been shown that the change in the punch cutting edge radius from r = 0 mm to r = 0.5 mm enables a seven-fold increase in the fatigue wear resistance. It was found that the change in the punch cutting edge rounding radius has an impact on the quality of the product (the greater the radius r, the worse the technological quality of the product). In experimental studies, the abrasive wear process was primarily investigated. For this purpose, the nibbling process was tested on S235JR + AR steel sheets with tools made of NC11LV/1.2379 steel without any coating and with an AlCrTiN layer. It was found that the special AlCrTiN layer used allowed for an increase in the resistance to abrasive wear, and thus increased the service life by approx. three times. The last element of the work is an assessment of the technological quality of the product after nibbling depending on the degree and type of stamp wear (quantitative and qualitative assessment).

ИССЛЕДОВАНИЕ ВЛИЯНИЯ ФОРМЫ РЕЖУЩЕЙ КРОМКИ НОЖЕВОГО ИСПОЛНИТЕЛЬНОГО ОРГАНА ГЕОХОДА НА ЭНЕРГОЕМКОСТЬ РАЗРУШЕНИЯ ПОРОДЫ ЗАБОЯ

The increase in the population creates prerequisites for the use of new undeveloped places, which include underground space. The development of underground space is associated with the construction of underground structures. A promising technology for the construction of underground structures is geokhodnaya. The basic element of which is a geokhod. As a rule, structures are built at shallow depths, which are characterized by rocks with a strength coefficient up to f = 1 on the scale of Professor M.M. Protodiakonov. Traditionally, the sinking of workings in these rocks is carried out by knife executive bodies. During the development and executive body design, one of the main indicators for evaluating its work is the energy intensity of the face rock destruction. As a result, a promising direction is to study the influence of the shape of the cutting edge of the knife executive body of the geokhod on the energy intensity of the destruction of the face rock. The article presents variants of schematic solutions of the geokhod knife executive body with a different shape of the knife cutting edge, developed on the basis of a functional and constructive approach to the development of constructive solutions and requirements for the geokhod executive bodies. It is established that the geokhod executive body geometric parameters, depending on the knife cutting edge shape, include: the angle of inclination of the knife with an inclined shape of the knife cutting edge; the radius of curvature of the knife cutting edge with a semi-convex and knife convex shape. The previously developed method of determining the face rock destruction energy intensity by the knife executive body of the geokhod is presented. For a promising direction of studying the influence of the geokhod knife executive body cutting edge shape on the energy intensity of the face rock destruction, the article provides initial data, which include the physical and mechanical properties of rocks and geokhod geometric parameters. As a result of the study, it was found that: the angle of inclination of the knife to the plane perpendicular to the axis of rotation does not significantly affect the face rock destruction energy intensity by the geokhod knife executive body; an increase in the knife cutting edge radius of curvature by the executive body of the geokhod leads to an increase in the energy intensity of the face rock destruction; given the physical and mechanical properties of the destroyed rock and the geometric parameters of the geokhod, it was found that with a knife cutting edge semi-convex shape and rкр = rг, the energy intensity of the face rock destruction is 1.4% less than with a straight shape. With a convex shape of the knife cutting edge and rкр = rг /2, the energy intensity face rock destruction is 8.3% less than with a straight shape.

Reverse identification of constitutive parameters of Inconel 718 alloy based on analytical model and thermo-mechanical loads analysis of machined surface

Finite element simulation is able to predict cutting force, temperature, stress distribution and chip formation. Constructing a constitutive model suitable for cutting simulation can accurately describe the state of the cutting process, which plays an important role in improving surface quality as well as optimizing cutting parameters and tool geometric design. Nickel-based superalloys are widely used in aerospace due to their excellent physical and mechanical properties at high temperatures. In this study, J-C parameters reverse identification of Inconel 718 alloy was carried out in both the solution annealed state and precipitation hardened state. The average cutting force and chip thickness were obtained by conducting orthogonal cutting experiments, after which the shear angle was calculated. Through quasi-static compression experiments, the yield strength, strain hardening modulus and hardening index of the material were then obtained. Considering the influence of the cutting-edge radius on cutting force during the cutting process, the Waldorf model was introduced into the analytical model in order to describe the deformation characteristics (strain, temperature, strain rate and stress) of the primary shear zone, after which the shear force was modified. The J-C constitutive parameters of the solution annealed state and precipitation hardened state were inversely identified by the intelligent optimization algorithm. According to the given range of cutting conditions, the accuracy of the method was verified through comparison with the cutting force and chip morphology of the finite element simulation. The differences in quasi-static and cutting dynamic mechanical responses of the two states were subsequently expounded. The effects of tool wear types and cutting parameters on the material flow characteristics at the tool tip as well as the thermal-mechanical load on the machined surface of precipitation hardened state Inconel 718 alloy were analyzed via numerical simulation. Accordingly, this study may provide insight into the identification of constitutive parameters of superalloys as well as the control of machined surface quality.