Tool Chip Friction Coefficient Research Articles

Study on the tool-chip friction coefficient of the bottom edge in high-speed internal cooling spiral milling hole

Study on the tool-chip friction coefficient of the bottom edge in high-speed internal cooling spiral milling hole

Effect of micro-grooved texture on cutting performance of tool under dry condition

To clarify the anti-adhesive properties of the textured tool, two types of micro-grooved textures were fabricated on the tool rake face. The cutting tests were conducted on aluminum alloys under no lubrication condition. Experimental results showed that the cutting force, tool–chip friction coefficient, and surface wear of the P_1 textured tool decreased. However, noticeable disadvantages were observed in samples with other textures. Detailed research indicated that the chip material (Al alloy) was easy to squeeze into and clog in the micro-grooved texture, due to low hardness and high ductility. In contrast, the cutting force, tool–chip interfacial friction, and wear of steel samples with T_1, T_2, and P_2 textures were all greater than that of the nontextured tool. The difference observed in these various textures signifies the importance of the small geometric size of the surface texture in the P_1 texture. Thus, an improvement of tool anti-adhesion with aluminum alloy material was obtained under dry cutting conditions.

Coating-thickness-dependent physical properties and cutting temperature for cutting Inconel 718 with TiAlN coated tools

IntroductionCoating-thickness-dependent physical properties can induce different cutting temperatures with physical vapor deposition (PVD) titanium aluminum nitride (TiAlN) ceramic-coated tools. The determination of the optimal TiAlN coating thickness is important to obtain superior coating physical properties and decrease the cutting temperature of Inconel 718 alloy. ObjectivesThe present study investigates the effects of coating thickness on the physical properties of TiAlN coatings and the cutting temperature during the machining of Inconel 718 alloy. The optimal coating thickness is also determined. MethodsFirst, the direct-current-arc method was utilized to deposit PVD Ti0.55Al0.45N coatings with thickness of 1.6 µm, 2 µm, 2.5 µm, and 3 µm, onto a cemented carbide substrate. Second, the coating-thickness-dependent physical properties were characterized and estimated with a radar chart. Third, the effects of coating thickness on coating antifriction were analyzed with the tool-chip friction coefficient when cutting Inconel 718 with PVD TiAlN coated tools. Both the maximum cutting temperature generated in the chip and the cutting temperature of the tool bodies were measured for analyzation of the thermal barrier effect of coating. Finally, the topographies of the deformed chip and tool-chip contact area were obtained and investigated to determine the effects of coating thickness on the cutting temperature. ResultsThe tool-chip friction coefficient and coating thermal barrier effect were affected by the coating thickness. Ti0.55Al0.45N coated tools with moderate coating thickness had fine antifriction effect with Inconel 718. The thermal barrier effect of Ti0.55Al0.45N coating was positively related to the coating thickness. ConclusionsThe optimal TiAlN coating thickness was determined as 2 μm, which resulted in superior physical properties and reduced the cutting temperature of Inconel 718.

Effects of bioinspired microscopic geometry of ceramic tool surface on tool temperatures in continuous and interrupted turning

This work was conducted to reveal the effects of bioinspired microscopic geometry of ceramic tool surface on tool temperatures in continuous and interrupted turning. Based on the solid-like and fluid-like features of chip, the bioinspired design of different patterns of microscopic geometry of tool rake face was carried out considering the integrated functions of both the epidermis of Onitis falcatus Wulfen and the scale of Carassius auratus. Friction coefficient between tool and chip was empolyed to analyze the influences caused by the bioinspired microscopic geometry on tool-chip interaction. Taking the relationship between tool-chip interaction and the heat source of tool into account, the influences of the bioinspired microscopic geometry on the heat source were identified. The effects of bioinspired microscopic geometry on tool temperatures were revealed on the basis of the constructed theoretical model for tool temperature. It was found that tilted hybrid array of microscopic dimples and grooves was most efficient in reducing tool-chip friction coefficient, heat source area, heat flux and tool temperature for each turning condition under consideration. The solid-like feature, fluid-like feature and flow direction of chip should all be considered in the design of bioinspired microscopic geometry in order to reduce tool temperature efficiently.

Effect of conical micro-grooved texture on tool–chip friction property and cutting performance of WC-TiC/Co cemented carbide tools

Purpose This study aimed to clarify the influence mechanism of conical micro-grooved texture on the tool–chip friction property and cutting performance of WC-TiC/Co cemented carbide tools under flood lubrication conditions. Design/methodology/approach Conical micro-grooved texture was fabricated on the tool rake face using laser texture technology. Metal cutting tests were conducted on AISI 1045 steel with conventional and developed tools for various cutting speeds (80 m/min to 160 m/min) and conical angles of micro-grooved texture (2 ° to 5 °) under flood lubrication condition. The effect of conical micro-grooved texture on the tool cutting force, tool–chip friction coefficient, surface roughness of the machined workpiece, and wear of the tool rake face was determined. Findings Unlike the conventional tools, the conical micro-grooved tools successfully resulted in reductions in metal cutting force, tool–chip frictional coefficient, surface roughness of the machined workpiece, and wear of the tool rake face. These reductions were more noticeable than those of conventional tools with increases in the cutting speed and conical angle of the micro-grooved texture. Detailed research indicated that conical micro-grooved channel exhibits a directional motion characteristic of liquid, which accelerated the infiltration of cutting fluid at the tool–chip interface. Substantial cutting fluid was supplied and stored at the tool–chip interface for the conical micro-grooved tools. Therefore, the conical micro-grooved texture on the tool rake face showed evident advantages in improving tool–chip friction and tool cutting performance. Originality/value The main contribution of this study is proposing a new conical micro-grooved texture on the tool rake face, which improved tool–chip friction and tool cutting performance.

Effect of symmetrical conical micro-grooved texture on tool–chip friction property of WC-TiC/Co cemented carbide tools

Surface texturing has been an attracting interest in metal cutting fields because of their tribological improvement at the tool–chip interface. A novel symmetric conical micro-grooved texture (S-5) was proposed and manufactured on the tool rake face using laser texture technology. The improvement effect of surface texturing (S-5) on tool–chip friction property was tested with AISI 1045 steel cutting experiment for various cutting speeds (80 to 160 m/min) under flood lubrication condition. Meanwhile, cutting performance of S-5 were evaluated against parallel micro-grooved texture tools (P-0) for a better clarification of the interaction mechanism. Experimental results indicated that surface texturing (P-0, S-5) on tool rake face all successfully resulted in a reduced cutting force, tool–chip friction coefficient, and tool surface wear than conventional tools (C-0). Moreover, S-5 showed a more obvious advantage in the improvement of tool–chip interfacial friction property than P-0.When cutting speed was smaller than 120 m/min, the friction coefficient obtained with the conventional (C-0) and textured tools (P-0, S-5) all showed a downward trend, and a smallest friction coefficient was appeared for S-5. When the cutting speed was greater than 120 m/min, an upward trend of friction coefficient was obtained for the C-0 and P-0 tools. However, a downward trend of friction coefficient was still existed for S-5. Detailed research indicated that the symmetric conical micro-grooved texture on the tool rake face could accelerate the infiltration speed of cutting fluid at the tool–chip interface. More cutting fluid would be supplied and stored at the tool–chip interface. So, symmetric conical micro-grooved texture on the tool rake face had a best lubrication effect of cutting fluid than conventional (C-0) and parallel micro-grooved texture tools (P-0).

A friction model having multiple factors for high-speed cutting of aluminum alloy 6061-T6

Tool–chip friction of high-speed cutting (HSC) is complex and involves nonlinear problems. This paper proposes a new friction model having multiple factors for HSC and investigates the multiple effects affecting the tool–chip friction coefficient. An experimental method of high-speed friction and an inverse method of obtaining the temperature of the friction interface are proposed. The proposed friction model reveals the inherent relationship between the friction coefficient and the multiple factors, and describes tool–chip friction in the HSC of aluminum alloy 6061-T6 accurately and improves the cutting simulation accuracy. It is also found that an increase in friction speed increases the friction coefficient and that an increase in friction temperature reduces the friction coefficient. However, an increase in ambient temperature clearly increases the friction coefficient at high temperature, and an increase in the normal load reduces the friction coefficient at low temperature and increases the friction coefficient at high temperature. The results provide a clear understanding of the mechanisms of friction speed and temperature, the ambient temperature, and the actual contact area in tool–chip friction of HSC.

On Cutting Temperature Measurement During Titanium Machining With an Atomization-Based Cutting Fluid Spray System

The poor thermal conductivity and low elongation-to-break ratio of titanium lead to the development of extreme temperatures (in excess of 550 °C) localized in the tool–chip interface during machining of its alloys. At such temperature level, titanium becomes highly reactive with most tool materials resulting in accelerated tool wear. The atomization-based cutting fluid (ACF) spray system has recently been demonstrated to improve tool life in titanium machining due to good cutting fluid penetration causing the temperature to be reduced in the cutting zone. In this study, the cutting temperatures are measured both by inserting thermocouples at various locations of the tool–chip interface and the tool–work thermocouple technique. Cutting temperatures for dry machining and machining with flood cooling are also characterized for comparison with the ACF spray system temperature data. Findings reveal that the ACF spray system more effectively reduces cutting temperatures over flood cooling and dry conditions. The tool–chip friction coefficient indicates that the fluid film created by the ACF spray system also actively penetrates the tool–chip interface to enhance lubrication during titanium machining.

An Approach of Tool-Chip Friction Coefficient Estimate for the Simulation of Machining Residual Stress

The tool-chip friction coefficient influences the simulation result of the residual stresses distribution seriously when Finite element software is used to simulate. This paper presents a new tool-chip friction coefficient estimate approach. Frist, a new mathematical model of cutting forces, the cutting speed, feed amount and the tool-chip friction coefficient was established in this paper based on the simulation results of Advant Edge, and then the tool-chip friction coefficient was reversed when the cutting forces are measured. Comparing the simulation residual stress distribution of the friction coefficient in calculation, average coulomb friction coefficient, the default friction coefficient with experimental result; it turns out the distribution of residual stresses in the friction coefficient of calculation approaches to experimental result.

Performance of the self-lubricating textured tools in dry cutting of Ti-6Al-4V

Surface textures were made using laser on the rake or flank face of the cemented carbide (WC/Co) inserts. Molybdenum disulfide solid lubricants were filled into the textured grooves to form self-lubricating textured tools. Dry cutting tests on Ti-6Al-4V were carried out with these self-lubricating textured tools and conventional tool. The machining performance was assessed in terms of the cutting forces, cutting temperature, chip thickness ratio, friction coefficient at the tool–chip interface, and tool wear. Results show that the cutting forces and cutting temperature of the self-lubricating textured tools were reduced compared with that of the conventional tool. The application of the self-lubricating textured tool with elliptical grooves on its rake face can reduce the tool–chip friction coefficient and the chip thickness ratio. The tool life of the textured tools is improved compared with that of the conventional tool. The effectiveness of the self-lubricating textured tools in improving cutting performance is related to the cutting parameter.

Finite Element Analysis of the Effects of Tool-Chip Friction on Cutting Temperature Field

The heat generation caused by tool-chip friction and chip deformation strongly influences the tool wear and tool life in metal cutting processes. The focus of this paper is on the effect of tool-chip on cutting temperature field. A series of ¬finite element simulations have been performed, in which a modifi¬ed Coulomb friction law is used to model the friction along tool–chip interface. A tool rake angle ranging from 10° to 45°, a inclination angle ranging from 0° to 20°, and a friction coefficient ranging from 0.1 to 0.6 have been considered in simulations. The results of these simulations show that the maximum cutting temperature increases with the increasing of tool-chip friction coefficient at different rake angle and inclination angle. The form of tool wear mainly appears as crater wear when the friction coefficient is less than 0.5, and the cutting edge tends to split when the friction coefficient is larger than 0.6.

Study on Characteristics and Principium of Rare Earth Carbide Tools

Carbide tools play key roles in present machine manufacture. The mechanical property and cutting performance of carbide tools are improved obviously when adding micro rare earth (RE) elements into carbide tools. By means of some apparatus, such as materials testing machine, Scanning Electron Microscope (SEM), dynamometer, microscope and electron probe microanalyser, the traditional and RE carbide tools, P30 (YT5 and YT5R), P20 (YT14 and YT14R), M10 (YW1 and YW1R), K30 (YG8 and YG8R), are studied and compared by doing a lot of experiments. These experiments show that the bending strength, fracture toughness and anti-impact capability of RE carbide tools are improved remarkably, and their hardness increased a little. Moreover, the cutting force, tool-chip friction coefficient and wear of RE carbide tools decreased in cutting. In addition, the effect and cutting principium of RE element to carbide tools are analyzed and discussed, which is beneficial to the research and application of RE carbide tools.

Material Characterization for Metal-Cutting Force Modeling

Widely applicable machining simulation programs require reliable cutting force estimates, which currently can be obtained only from process-dependent machinability databases. The greatest obstacle to developing a more basic, efficient approach is a lack of understanding of material yield and frictional behavior under the unique deformation and frictional conditions of cutting. This paper describes a systematic method of specifying yield stress and friction properties needed as inputs to process-independent cutting force models. Statistically designed end turning tests are used to generate cutting force and chip thickness data for a mild steel and an aluminum alloy over a wide range of cutting conditions. Empirical models are fit for the cutting force and model-independent material parameters such as the tool-chip friction coefficient and shear stress on the shear plane. Common material yield behavior assumptions are examined in light of correlations between these parameters. Results show no physically meaningful correlation between geometric shear stress and strain measures, a weak correlation between geometric stress and strain rate measures, and a strong correlation between material properties and input variables such as cutting speed and rake angle. An upper bound model is used to fit four- and five-parameter polynomial strain-rate sensitive constitutive equations to the data. Drilling torques calculated using this model and an empirical turning force model agree reasonably well with measured values for the same material combination, indicating that end turning test results can be used to estimate mean loads in a more complicated process.