Tool-chip Contact Length Research Articles

Machinability Performance of Single Coated and Multicoated Carbide Tools During Turning Ti6Al4V Alloy

AbstractThis paper presents the machinability performance of uncoated, single-coated, and multicoated carbide tools during turning of Grade 5 (Ti6Al4V) Titanium alloy, which is challenging to machine due to its distinctive material properties. Coated tools with single-coated Titanium Aluminium Nitride (TiAlN) and multi-coated layer of Titanium Aluminium Nitride with Aluminium Chromium Nitride (TiAlN + AlCrN) coated inserts were utilized to assess surface roughness (Ra), tool wear rate (R), and chip morphologies under various cutting conditions using dry machining. Analysis of the used tools revealed that coated tools exhibited improved tool life and surface quality compared to uncoated tools across all cutting conditions. Multi-coated tools of TiAlN + AlCrN demonstrated a tool life increase of up to 15% compared to uncoated and single-coated tools, with surface roughness improvements ranging from 30 to 45% depending on cutting speed. Chip morphology analysis indicated an increase in the chip reduction coefficient with higher cutting speeds for all tool types. Coated tools exhibited the lowest chip-reduction coefficient due to the presence of TiAlN and AlCrN coatings, which control the tool chip contact length. Conversely, uncoated chip morphology resulted in larger chip thickness values compared to coated tools, particularly at cutting speeds above 100 m/min, attributed to poor heat dissipation and chemical reactions at the tool chip interface. Energy dispersive X-ray scanning electron microscopy (SEM/EDXS) analysis of worn uncoated inserts revealed a higher tendency towards Titanium adhesion compared to coated tools. The proposed multi-layer coatings of (TiAlN + AlCrN) used for dry machining proved highly beneficial for achieving economic machining objectives and may reduce the need for lubrication when processing Ti6Al4V alloys.

Tool chip contact length analysis of dry and cryogenic turning of aerospace alloy Ti-6Al-4V

Tool chip contact length is a vital machining index being representative of manufacturing efficiency. Various machining factors including tool wear and energy consumption are governed by tool chip contact length. The current work was undertaken to make a comparative analysis of dry and cryogenic turning of Ti-6Al-4V in terms of their sustainability and productivity indices. During experimentation, cutting speeds of 50 m/min and 125 m/min were selected working at feed rates ranging from 0.16 mm/rev to 0.24 mm/rev. Scanning electron microscopy was utilized to analyse the results. It was observed that machining under cryogenic conditions, in comparison with dry conditions, resulted in up to 51 % lower tool chip contact length. The results were also investigated in terms of chip formation for both machining environments. In addition, benefits of lower tool chip contact length were quantified in terms of lesser tool wear and better energy consumption. Tool chip contact length and chip formation analysis, indicative of the machining process efficiency, highlights that cryogenic condition is more sustainable and productive than dry conditions.

Experimental investigation on turning Inconel 713C under different cooling conditions using a new honeycomb-textured tool

ABSTRACT Tool surface texturing is a new sustainable method for machining hard-to-machine materials. The present study focuses on the new honeycomb texture (mimic of bee’s honeycombs) containing hexagons forming between thin vertical walls. The important novelty in this work is the cutting performance of honeycomb texture on Inconel 713C was examined under cutting parameters and different cooling conditions: dry untextured (T1), dry textured (T2) tool, impregnated solid lubricant (hexagonal boron nitride (hBN)) textured tool (T3), MQL (coconut oil) with textured tool (T4), and NMQL (0.20 wt.% hBN + coconut oil) with textured tool (T5). Compared to plain tools, NMQL to honeycomb texture reduced flank wear by 53.2%, roughness by 43.2%, turning force by 27%, and cutting temperature by 47.7%. Honeycomb texture with MQL (T4) and NMQL (T5) reduces flank surface Ni element diffusion during turning. Nanofluid-textured inserts (T5) demonstrated higher shear angles, lower chip curl diameter, and shorter tool-chip contact length than other conditions.

A hybrid numerical and experimental approach towards Ti6Al4V alloy sustainable orthogonal turning

By 2030, United Nations members should modernize their manufacturing systems to make them more sustainable and resilient. In machining this includes, managing consciously the type and amounts of metalworking fluids (MWFs), as well as the delivery systems. Indeed, shifting from flood cooling with mineral-based emulsions to near-dry methods, such as minimum quantity lubrication (MQL) is crucial to increase sustainability. Thus, the objective of this study was to determine the conditions (feed and speed) for Ti6Al4V orthogonal turning where the use of MQL was found to be more effective than flood cooling. To attain that, digital twins were created to study key process responses, such as cutting force, cutting power, specific cutting force, peak tool temperature, chip curling radius, and material removal rate. The numerical database was used to find optimal conditions, which were reproduced experimentally. The friction coefficient, tool-chip contact length, and chip morphology were studied experimentally and used to validate the digital twins. It was observed that the influence of the cutting speed and feed rate was two-folded, as they not only directly impacted the alloy thermo-mechanical response (exerting a more pronounced effect than the use of lubrication) but also played a crucial role in the effectiveness of the MQL system. Indeed, the MQL system performed better when low feed and/or speed were combined. Situated within the broader framework of cleaner production, the research highlights the transformative potential of process virtualization with digital twins in facilitating the planning and adoption of responsible fluid practices in industrial machining, essential for reducing the environmental impact of industrial machining.

Sustainable approach for machining of Ti6Al4V using micro-pillar textured turning tool insert

The use of cutting fluids (CF) in metal cutting is questioned due to environmental and biological impacts, encouraging the adoption of dry machining to minimize these effects. However, dry machining accelerates tool wear, particularly in difficult-to-machine materials like Titanium and Nickel alloys. Approaches, such as rake surface texturing, address this challenge and promote sustainability in metal cutting. This study explored the impact of an innovative micro-pillar texture pattern fabricated using a combination of Laser Beam Micro Machining (LBμM) and Reverse Micro Electrical Discharge Machining (RμEDM) for the dry machining of Ti6Al4V. The investigation considers various parameters, including tool wear, contact length, titanium adhesion, cutting forces, cutting temperature, and chip morphology. An indirect approach was adopted to estimate the temperature of the tool tip using the temperature measured at a distant location. Implementing the textured tool with 15 μm deep micro-pillars in the dry machining of Ti6Al4V exhibited the best overall performance for various responses. A notable reduction of more than 40% for both tool-chip contact length and titanium adhesion, compared to a plain tool, indicated a perceptible decrease in the seizure zone at the interface. Moreover, the textured tools demonstrated a remarkable maximum reduction of 56.4% in flank wear, ensuring the prolonged retention of a sharp cutting edge. The responses for contact length, adhesion, and flank wear contributed to an 18.8% decrease in cutting force and a substantial 45.7% reduction in thrust force. Force analysis further confirmed the directional independence of the texture pattern. Under the influence of surface texturing, chip morphology changed to shorter, untangled, and tightly curled, with a 30.8% reduction in curl radius. A theoretical estimation based on the minimum energy approach was also performed to demonstrate an increment in the shear plane angle.

Prediction of tool-chip contact length based on slip-line modeling of orthogonal cutting with rounded-edge cutting tools

It is known that no cutting tool has a perfectly sharp cutting edge and that there is always a small rounding on the cutting edge of the tool. In this study, a new tool-chip contact length equation is presented for cutting tools with rounded-edge in orthogonal cutting. This equation was obtained based on a newly developed slip-line model. This newly developed slip-line model has rounded-edge cutting and considers the presence of a dead metal zone in front of the cutting edge. To verify the newly developed tool-chip contact length equation, experimental studies were conducted at various cutting speeds and uncut chip thickness values at both 0° and 6° rake angles, using cutting tools with 50 μm–100 μm–150 μm edge radii. Orthogonal cutting experiments were carried out using the shaping-based quick stop device and brass (CuZn30) material was chosen as a workpiece that allows continuous chip formation without built-up edge. Strong correlation was observed between the experiment results and values that were obtained from the newly developed tool-chip contact length equation.

Cutting performance and cutting fluid infiltration characteristics into tool-chip interface during MQL milling

The insufficient infiltration of cutting fluid at the tool-chip contact interface during machining poses a substantial challenge to achieving clean and efficient cutting processes. Key to enhancing the infiltration efficiency of cutting fluids lies in understanding their penetrative characteristics within the tool-chip cutting region. Thus, analyzing the milling performance under varying lubrication environments and cutting parameters forms a fundamental prerequisite to this research. In this study, we experimentally investigated the influences of cutting parameters on cutting force and cutting temperature in dry and minimum quantity lubricant (MQL) milling. In addition, we presented the friction state at the tool-chip interface, incorporating the friction coefficient into our analysis. Moreover, we explored the infiltration characteristics of oil mist fluid within the tool-chip contact region via fluid simulations. The tool wear mechanisms under various lubrication conditions were also elucidated. Subsequently, we established three-stage infiltration models to ascertain the conditions conducive to the formation of stable lubricating films and revealed the internal mechanisms dictating MQL penetration. The results disclose that the cutting force, cutting temperature, and friction coefficient of MQL milling decrease by 10–25%, 9%, and 16% respectively at a cutting speed of vc = 100 m/min, feed rate of fz = 0.4 mm/rev, and axial cutting depth of ap = 0.3 mm. However, as cutting parameters increase, the MQL's ameliorative effect on cutting performance diminishes. The underlying cause for this is the expansion of the tool-chip contact length and the increased chip curling radius, which significantly obstruct the injection of MQL oil mist droplets, resulting in a weakened infiltration effect. In conjunction with the conditions necessary for lubricating film formation, it is evident that an increase in cutting parameters is detrimental to improving the infiltration capacity of the cutting fluid into the capillary.

Study on tool wear mechanism and chip morphology during turning of Inconel 713C by textured inserts

The present study aims to analyze the tool wear mechanism and chip morphology during dry (D) and graphene solid-lubricant (S), turning of Inconel 713C with a new novel textured (honeycomb (T2) and rectangular(T3)) and further compare with the textured dimple tool (T1). In addition, the performances were compared with the untextured tool (T0). The machining tests for all conditions were carried out at different levels of cutting speeds (75 m/min and 150 m/min), feed rate (0.1 mm/rev and 0.2 mm/rev), and a constant level of depth of cut (0.5 mm). Honeycomb-textured cutting tools performed better. Improvements of 33.3 % (T1D), 50 % (T3D), and 75 % (T2D) without graphene and 66.6 %(T1S), 75 % (T3S), and 100 %(T2S) with graphene are observed compared to T0. The primary mechanism for the better performance of T2S was the reduced tool chip contact length (8–50 %), chip width (30.4 %), friction coefficient (57.4 %), chip thickness (17.8 %), and higher shear angle (14.2 %) compared to dry textured and untextured tools at the end of tool life. Additionally, the T2S (solid lubricant-impregnated honeycomb) demonstrates a decrease in equivalent chip thickness (19.8 %) and an increase in shrinkage factor (17.2 %) at worn-out tool life conditions at high cutting speed and feed rate. Under the same conditions, T2S has 27.3 % lower cutting force and 36.2 % lower surface roughness of machined workpieces compared to the untextured tool at the end of tool life. The chip micrograph reveals the chips are shorter, and the chip radius is lower for T2S tools with smooth friction tracks and fine deformed lamella on the free surface of the chip. Under SEM, flank wear, adhesion materials, abrasion, micro-chipping coating peeling, and BUE were dominant wear mechanisms. However, T2S tools effectively reduce Ni elements' diffusion and suppress the built-up edge's adhesion by improving friction characteristics at the tool-chip interface region. Lastly, the outcomes of experimental results suggest that the honeycomb texture for dry machining of Inconel 713C.

The Study of Tool Wear Mechanism Considering the Tool–Chip Interface Temperature during Milling of Aluminum Alloy

ADC12 aluminum alloy has been widely used in the aerospace, ship, and automotive fields because of its high specific strength, excellent die-casting performance, and wear resistance. Adhesion wear is the main wear mechanism of high-speed milling ADC12 aluminum alloy. The most important factor affecting adhesion wear is the tool–chip interface friction, which is directly manifested in the tool–chip interface temperature. Therefore, the temperature variation during the milling of aluminum alloy is analyzed using a temperature field model and infrared temperature measurement technology. Then, the tool wear morphology and the tool wear land width are observed using a scanning electron microscope. Finally, the tool wear mechanism considering the tool–chip interface temperature is discussed. The tool–chip interface temperature is related to the friction angle, tool–chip contact length, and friction force at the rake face, which increases first and then decreases as the cutting speed and feed rate increase. During the formation of the adhesive layer, the tool–chip interface temperature increases, the change rate of the cutting force and the tool wear rate increase, and adhesion, oxidation, and abrasive and delamination wear are generated on the tool surface. With the increase in temperature, the tool wear rate increases, the molten adhesive layer on the tool surface is accompanied by crack propagation, and adhesion wear, oxidation wear, and abrasive wear occur on the tool surface.

Experimental Investigation of the Derivative Cutting When Machining AISI 1045 with Micro-Textured Cutting Tools

In the context of satisfying sustainability requirements nowadays, dry machining is one of the ideal strategies to eliminate the environmental and human health burdens of machining processes. In addition, micro-textured cutting tools are used to improve the performance of dry machining processes. Micro-textures reduce the chip-tool contact length and thus reduce friction and heat, which results in fewer cutting forces and temperature. However, the action of micro-cutting of the bottom side of the chip, which is known as derivative cutting, cuts down the gains of using textured tools, where derivative cutting leads to higher cutting forces, heat, and tool wear. This study aimed to investigate the effects of significant texture design parameters (i.e., micro-groove width) when cutting AISI 1045 steel using different machining parameters (i.e., 75 m/min and 150 m/min of cutting velocity, 0.05 and 0.10 mm/rev of feed). Three different textured cutting tool designs were prepared using the laser texturing technique and then utilized in machining experiments. In addition, the measured machining outputs were forces, power consumption, flank wear, and surface roughness. There were no marks for the derivative cutting when using the textured cutting tool with the narrowest micro-grooves according to the obtained microscopical images after the machining tests. In addition, the textured cutting tool, which included the narrowest micro-grooves, showed better performance compared to the non-textured cutting tool and the other textured tool designs in terms of cutting and feed forces, power consumption, flank tool wear, and surface roughness at the used cutting conditions. This confirmed that the careful optimal design of the micro-textured tools can reduce or eliminate the severity of the derivative cutting, and thus improve the overall machining performance.

Investigation on turning of Inconel 718 using differently coated microtextured tools

In this paper, the performance of three microtextured tools in machining Inconel 718 high-temperature alloy under two different coating conditions was investigated using the finite element method. Firstly, the theoretical tool-chip contact length model of the microtextured tool is established. Secondly, the theoretical model of cutting force and cutting the heat of the surface weave tool is established using the theoretical tool-chip contact length model. The theoretical analysis of cutting force and cutting temperature of the microtextured tool is carried out according to the variation law of the theoretical tool-chip contact length. And finally, the finite element simulation model is established. The effect of changing the coating material on the machining performance of microtextured tools is discussed by changing the coating material on the tool surface. By establishing the simulation model, the changing patterns of cutting force, cutting temperature and effective stress of the three microtextured tools are compared under different coating materials. Adding coating materials to the tool surface can effectively improve machining efficiency. In addition, it is proposed that different microtexture shapes produce different degrees of secondary cutting during the turning of microtextured tools.

Chip morphology and tool wear investigation in high-speed machining of AZ61 magnesium alloys using vegetable-oil based cutting fluid

ABSTRACT Lightweight alloys play a vital role in the development of automotive, biomedical and aerospace industries as well as other industrial sectors. The current study investigates the machinability of AZ61 magnesium alloy within a vegetable-oil-based MQL environment through high-speed orthogonal cutting. A tool wear and chip morphology examination are conducted along a full factorial experimentation to allow for adequate machinability testing. The usage of Grey Relational Analysis was invoked to allow for a multi-variant optimisation of input parameters such as MQL flow rate, cutting speed, and feed based on output responses, such as chip compression ratio, chip segmentation ratio, tool-chip contact length, and shear angle as well as tool wear evolution. Through the analysis of the formulated signal-to-noise data, it was found that the optimal cutting parameters were an MQL flow rate of 80 ml/h, cutting speed of 250 m/min and feed of 0.3 mm/rev. The optimal cutting conditions resulted in a Grey Relational Grade improvement of 0.177 as compared to the referenced experimental trail. The analysis of variance further concluded that the feed was the highest contributing input parameter at 38.04% followed by the MQL flow rate and the cutting speed.

Time-Varying Tool-Chip Contact in the Cutting Mechanics of Shear Localization

Abstract Shear localization is the dominant chip formation mechanism in machining of high performance metallic components, such as those made of titanium and nickel-based alloys. This paper presents an analytical thermo-mechanical model considering a new tool-chip contact mechanism due to shear localization. First, it is experimentally shown that the sticking and sliding contact lengths fluctuate with the frequency of shear localization. Second, a cutting mechanics model is developed considering the shear band formation, its rolling on the tool’s rake face, and the time-varying tool-chip contact length with experimental validation. Finally, the transient temperature at the tool-chip interface is predicted by taking the rolling phenomenon and the time-varying heat sources at the tool-chip interface into account. The proposed model shows that at the beginning of each segmentation cycle, the entire tool-chip contact length is dominated by sliding condition with negligible sticking length. When the tool advances, new workpiece material piles up in its front with an increase in the sticking length. Meanwhile, the sliding length decreases due to the drop in the load-bearing capacity of the shear band. When enough material piles up in front of the tool, a new shear band forms, and the entire contact length returns to the sliding condition. This process repeats each time a shear band occurs, causing the cyclic formation of shear bands and time-varying nature of the tool-chip contact length, therefore influencing the temperature and stress evolution at the tool-chip interface.

Machinability analysis of Ti-6Al-4V under cryogenic condition

Aerospace alloys are termed as hard to cut materials owing to their low thermal conductivity, high temperature strength and elevated chemical reactivity. Cryogenic conditions can be effectively deployed to improve the machinability and productivity while addressing environmental and sustainability concerns connected with high tool wear and the use of conventional cutting fluids. Current work was undertaken to develop a novel tool wear map under cryogenic condition using cutting speed and feed rate as input variables. The developed map was demarcated into regions of low, moderate and high tool wear zones in addition to an unusually high wear zone, termed as avoidance zone existing between cutting speeds of 65–95 m/min and feed rates of 0.18–0.22 mm/rev. Characterization of developed map in terms of tool chip contact length revealed its direct relationship with cutting speed and feed rate accounting for the formation of different wear regions. Elemental analysis of avoidance zone detected high presence of TiN which results in larger tool chip contact length owing to its higher thermal conductivity. Chip morphology characterization highlighted an increase in chip compression ratio and decrease in shear angle due to the reduction of effective tool rake angle, further elevating the cutting zone temperature promoting wear. SEM and EDS spot analysis indicated the presence of adhesive and diffusion-dissolution wear mechanisms as the tool wear progresses. Comparative analysis with dry condition indicated that tool life is enhanced up to 100% using cryogenic media. Analysis of cryogenic tool wear map underscored the importance of careful choice of machining parameters in terms of increase in MRR up to 36% and tool life up to 58%. Overall, cryogenic tool wear map presents graphical interpretation of the machinability of Ti–6Al–4V in terms of tool wear.

Analytical and experimental investigations of rake face temperature considering temperature-dependent thermal properties

In metal cutting, rake face temperature is a critical factor affecting the quality of processed parts and tool wear. However, this temperature is difficult to estimate because of the high strain rate and barrier effect of chips. This paper presents an integrated analytical and experimental approach to predict rake face temperature, which proposes an improved analytical model considering temperature-dependent thermal properties. The considered temperature properties mainly include thermal conductivity (TC) and thermal diffusivity (TD) of the workpiece and cutting tool, which has rarely been considered in previous studies. With the measured cutting force and tool–chip contact length, the improved analytical model can predict the tool temperature based on an adaptive method to match the thermal properties and temperature at an arbitrary point. Moreover, a relatively new in situ measurement method for directly capturing the radiation of the rake face temperature using a two-colour pyrometer and slotted workpiece is presented. This new technique can eliminate the barrier effect of the chip without interrupting the cutting process. This experimental method is proved to be able to stably measure the rake face temperature with a deviation less than 3%, furthermore, the captured temperatures are much higher when compared with conventional methods under the comparable cutting conditions. The comparison of rake face temperature between the predicted and the measured results shows an average prediction error of 8.6% of the proposed method, proving its superiority over conventional models using constant thermal properties.

Assessment of sustainability of machining Ti-6Al-4V under cryogenic condition using energy map approach

Sustainability of a manufacturing system is of significant importance to its overall efficiency and output. The issue becomes more pertinent during the machining of hard to cut titanium alloys which draws excessive amount of energy. Process map are effective tools that readily provides machinability information of materials of manufacturing importance to process planners. Titanium alloys, owing to their usage in high volumes, are well-mapped but only under dry conditions. The current research focuses on the development of energy consumption map of titanium alloy Ti-6Al-4V employing single point turning under cryogenic conditions. Cryogenic cooling is known for its convenience for green manufacturing as opposed to conventional coolant. Cutting speed and feed rate are used as variable machining parameters over a wide spectrum using full factorial design of experimentation. Energy consumption is represented by specific cutting energy due to its machine-tool independent nature. The map region was demarcated into low, moderate and high energy zones. Analysis of the developed novel map revealed underlying mechanics of machining and provided deeper insight into the factors effecting energy consumption. Energy consumption was found to be more dependent on cutting speed than feed rate. Tool chip contact length was found to decrease due to the reduction of slip region under cryogenic conditions. Analysis of chip morphology revealed that chip shear angle and compression ratio decreased with increase in cutting speed resulting in higher energy consumption. The significance of cryogenic map is also underscored in its utility on the shop floor for selection of optimum machining parameters for higher productivity in addition to its sustainable and environmental friendly nature. In comparison with dry energy map, a reduction in energy up to 16% is observed which highlights the sustainability of cryogenic energy map. The utility of cryogenic energy map can also be ascertained from the fact that productivity can be increased by 156% in terms of material removal rate by careful selection of appropriate machining parameters. Overall, the developed cryogenic map is a vital asset of manufacturing systems as it collectively serves the purpose of sustainability and cleaner production.

Temperature field evolution and thermal-mechanical interaction induced damage in drilling of thermoplastic CF/PEKK – A comparative study with thermoset CF/epoxy

Although new generation carbon fibre reinforced thermoplastic (CFRTP) such as carbon fibre reinforced polyetherketoneketone (CF/PEKK) is a promising sustainable alternative to the conventional thermoset carbon fibre reinforced plastic (CFRP), there is a lack of literature regarding its machining performance. This is the first study unveiling the machining temperature evolution during drilling of CF/PEKK and its potential impact on the associated material damages. Through a comparative study with the thermoset CF/epoxy, the disparate drilling performance of the two composites has been uncovered, and the results were found to be closely related to the materials' thermal/mechanical properties. Specifically, CF/PEKK produces continuous chips due to its excellent ductility and thermal sensitivity, whereas CF/epoxy produces segmented chips due to its brittle nature. CF/PEKK generates up to 40 N (50.5 %) higher thrust force, 87.6 °C (98.9 %) higher hole wall temperature and 61.1 °C (48.8 %) higher chip temperature than that of CF/epoxy. This has been correlated to the longer tool-chip contact length of CF/PEKK and its unique chip morphology. Despite the greater thrust force/temperature generation, CF/PEKK shows 55.7 % lower delamination damage as compared to CF/epoxy, and this is owning to its excellent interlaminar toughness. This study establishes a more in-depth understanding into the drilling performance of thermoplastic CF/PEKK and thermoset CF/epoxy and also provides guidance on the high performance manufacturing of next generation composites.

Improving dry machining performance of surface modified cutting tools through combined effect of texture and TiN-WS2 coating

In this research work, investigation on different surface modification techniques on cutting tools such as TiN-WS2 coating (T2), textured cutting tool (T3) and TiN-WS2 coated textured tool (T4) in dry machining of Ti-6Al-4V has been carried out and compared with commercial tool (T1). The presence of (002) orientation corresponding WS2 was observed in the diffraction pattern and this in turn was said to provide lubricity properties to the coatings. The cutting force generated during machining was reduced by 14 % for T4 tool when compared to T1. The T4 tool showed an increase in the shear angle by 7.5 % and decrease in coefficient of friction by 47 %. The prime mechanism attributed to the better performance of cutting tool was reduced tool-chip contact length. The T4 tools showed a 13 % reduction in tool-chip contact length when compared to commercial tools. The tool life of the T2, T3 and T4 tools was improved by 35 %, 29 % and 43 % respectively in comparison to commercial tools. The TiN-WS2 coatings, through its effective lubricity properties have said to nullify the effect of coating affinity between the tool and workpiece as evidenced by the absence of built-up edge on the tool rake face while machining using TiN-WS2 coated tool. The combined effect of TiN-WS2 coatings and surface textures have resulted in better machining characteristics, suggesting it as a suitable surface modification for dry machining of Ti-6Al-4V.

Research on CFRP cutting mechanism by the micro-textured tool using macroscopic and microscopic numerical simulations

Carbon fiber reinforced plastics (CFRP) composites are the most widespread advanced composite materials. Still, machining with traditional tools quickly generates defects such as high cutting forces and severe subsurface damage, while micro-textured tools can improve CFRP machining performance. Therefore, to reveal the cutting mechanism of CFRP processing by micro-textured tools and guide the tool design, macroscopic and microscopic orthogonal cutting models were established in this study, which compared and analyzed the material removal process and the indicated topography of unidirectional CFRP with different fiber orientations (0°, 45°, 90°, and 135°) by traditional tools and micro-textured tools, and the accuracy of the models was verified with experiments. Compared with traditional tools, micro-textured tools reduce cutting forces by minimizing the tool-chip contact length to reduce friction and converting the fiber failure form from crush failure to shear failure. Meanwhile, the texture on the rake face enables cutting burrs, effectively improving the surface quality of the workpiece and suppressing the depth of subsurface damage. In addition, the influence of different texture parameters on the machining quality of the workpiece was analyzed.

Determination of the Chip–Tool Contact Length in Orthogonal Cutting

Abstract This work presents an experimental–numerical approach aimed at determining the chip–tool contact length during orthogonal cutting of annealed AISI 4340 steel (223 HV) with TiN-coated tungsten carbide inserts. Initially, pin-on-disc tests were performed, followed by orthogonal cutting tests. The components of the cutting force were used to calculate the coefficient of friction in orthogonal cutting, and its value was compared with those obtained under sliding. Moreover, the cutting force components obtained experimentally were used to assess the reliability of the finite element model and estimate the temperature in the cutting zone. The contact length between chip and rake face was calculated based on the experimental feed force and shear strength of the work material and was compared with the results provided by an analytical model. The experimental–numerical approach can be considered more accurate due to the fact that it considers the effect of the tool–chip interface temperature on the shear strength of the work material. However, the analytical model is quite straightforward, since it only requires the values of chip thickness and undeformed chip thickness to estimate the tool–chip contact length.