Chip Thickness Ratio Research Articles

OPTIMISATION OF A NEEM OIL BASED MINIMUM QUANTITY LUBRICATING (MQL) SYSTEM PARAMETERS FOR THE ORTHOGONAL MACHINING OF MILD STEEL

Cutting tools experience early failure and dimensional variation due to the high temperature developed during machining. Conventional cutting fluid applications do not successfully remove heat because they do not reach the chip-tool contact. Operators on the work floor may experience the adverse side effects of cutting fluids, such as skin and respiratory issues. As a result, a different lubricating method is necessary for machining without harming the tool-workpiece, which would also be advantageous for health and the economy. This research aims to develop and evaluate the efficiency and optimization of minimal use of Neem seed oils as lubrication for the Taguchi L9 array-based design for machining of mild steel. The Taguchi optimization technique was used to examine the impact of the neem oil based Minimum quantity lubrication (MQL) system (with flow rate, air pressure and nozzle diameter as factors) on the workpiece temperature and chip thickness ratio at cutting speeds of 260 rpm and 470 rpm. The outcome demonstrated that optimal settings at 260 rpm were a flow rate of 50 ml/hr, air pressure of 1.5 bars, and nozzle diameter of 0.8 mm for workpiece temperature, and a flow rate of 100 ml/hr, air pressure of 1 bar, and nozzle diameter of 0.8 mm for chip thickness ratio. At 470 rpm, optimal settings for workpiece temperature were a flow rate of 50 ml/hr, air pressure of 1.5 bars, and nozzle diameter of 0.5 mm, while chip thickness ratio optimization indicated a flow rate of 100 ml/hr, air pressure of 1 bar, and nozzle diameter of 0.5 mm.

Experimental investigation on extrinsic size effect in micro-orthogonal cutting of commercial aluminium alloy

The achievable precision in micro-machining is constrained by a phenomenon known as the size effect. The edge radius of the tool significantly influences the size effect leading to non-proportional scaling of process performance. The process becomes unscalable below a certain ratio of uncut chip thickness to edge radius termed as critical relative tool sharpness (RTS). Despite extensive studies on the size effect associated with non-linear process performance, very limited studies have focused on the critical RTS range. In the present study, orthogonal cutting experiments were conducted on a commercial aluminium alloy (Al6060) with different cutting-edge radiuses in the RTS range of 0.5 to 0.01. Extensive analysis of the morphology of the chips and tool-work material adherence has been carried out and correlated with the observed size effect on surface integrity. One of the key findings in this study was the size effect in the chips with respect to the chip curl radius and pitch. Between RTS 0.5 and 0.09, an increase in chip curl and pitch is observed, followed by a sharp fall up to RTS 0.07. In addition, another notable phenomenon was the formation of dual-layered chips with deformed layer on the rake side and lamellae like features on the free side. Furthermore, size effect was observed in surface roughness, surface hardness and flank adherence. In summary, the present investigation offers a comprehensive understanding of the size effect within the critical RTS range elucidating its multifaceted impact on micro-cutting.

Multi-Criteria Optimization of Al2O3-ZrO2(Y2O3)-based Self-lubricating Composite Cutting Tools for Increasing Shear Angle, and Wear Resistance in Machining Processes

Abstract In the present investigation, self-lubricating cutting tools were fabricated by adding various elements such as NiCr, Ag, Mo, SrSO4, and CaF2 to Zirconia Toughened Alumina in order to overcome the difficulties that occurred in dry machining. Three significant process parameters; cutting speed (50, 125, 200, and 275 m/min), feed rate (0.1 and 0.2 mm/rev), and depth of cut (0.1 and 0.2 mm) were selected for the machining process. The performance measures such as chip thickness ratio, shear angle, and tool wear, were investigated. The experimental runs were conducted with Taguchi L8 mixed-level orthogonal array. Technique for Order of Preference by Similarity to Ideal Solution is a multi-criteria decision-making method used to determine the best alternative from a set of options. Turning experiments have been performed on the AISI 4340 steel workpiece with various combinations of machining parameters. The findings revealed the incorporation of SrSO4 and Mo at 10Wt.% and CaF2 at 5Wt.% (i.e., self-lubricating cutting tool-4) achieved better mechanical properties and wear resistance due to the formation of a self-lubrication layer on the rake face of the cutting tool. A confirmation experiment is executed in order to verify the outcomes in the end. Finally, there is a noticeable improvement in the outcomes compared to the base cutting tool, i.e., chip thickness ratio is 35.77%, shear angle is 27.31%, and tool wear is 58%. The mechanism for improving performance measures is discussed in detail.

Modelling cutting force for turning AISI 304 stainless steel with PVD-AlTiN coated, PVD-AlTiN coated-microblasted, and MTCVD-TiCN/Al2O3 coated tools

ABSTRACT Stainless steel is challenging to machine, and to avoid any negative consequences, it is essential to comprehend the cutting forces. With this view, this study has developed a cutting force model for turning AISI 304 stainless steel with the most preferred PVD-AlTiN coated (C-type), PVD-AlTiN coated-microblasted (CMB), and MTCVD-TiCN/Al2O3 coated carbide tools (MTCVD). Empirical models are developed to predict the chip thickness ratio, the normal shear angle, and sharp tool cutting forces. Studies showed the reduction in forces with the cutting speed for C-type, CMB, and MTCVD tools was 12–20%, 11–32%, and 6–29%, respectively. However, the corresponding increases with the feed and depth of cut were 60–134%, 125–146%, and 97–178%; 76–186%, 55–384%, and 14–274%, respectively. Additionally, a cutting force model considering the tool wear effect is developed for MTCVD tools, which exhibited lower tool wear compared to other tools. The study accurately predicted sharp tool and worn tool cutting forces, showing good quantitative agreement with experimental results with an average error of less than 10%. However, some discrepancies were observed beyond the flank wear length of 0.2 mm. It was due to the chipping of the coating layers and the pitting of the substrate from the nose area.

Machinability of Inconel 718 using unitary and hybrid nanofluids under minimum quantity lubrication

ABSTRACT In the current study, unitary and hybrid nanofluids are used with minimal lubrication to examine Inconel 718’s machinability. Nanofluids are obtained by dispersing unitary and mixed amounts of aluminium oxide, multi-walled carbon nanotubes, and graphene nanoparticles into palm oil. Initially, turning experiments were performed with pure palm oil and different unitary and hybrid nanofluids using differently coated carbide tools to obtain the best combination of the type of nanofluid(s) and coated tool for the lowest tool wear. Further, the cutting forces, surface roughness, chip thickness ratio, chip morphology, and shear angle were obtained, varying with the cutting parameters for the best combination of nanofluid(s) and the tool. The analysis of worn-out tools has been performed through images captured using optical and scanning electron microscopes. The study indicates that aluminium titanium nitride-coated tools outperform titanium aluminium nitride-coated tools with hybrid aluminium oxide and multi-walled carbon nanotube-based nanofluid, followed by a unitary aluminium oxide-based nanofluid. It could be attributed to the higher thermal conductivity and surface tension of aluminium oxide nanoparticles and the better lubricating and cooling capabilities of multi-walled carbon nanotubes. Comparatively lower performance was observed with graphene-based nanofluid due to severe agglomeration that adversely affected the homogeneity of the fluid.

COMPARATIVE ANALYSIS OF METHODS FOR CUTTING SPUR GEARS BASED ON TECHNICAL AND ECONOMIC PARAMETERS

The results of the simulation and study of the process of cutting gears by the traditional method of hobbing and the new radial-circular method (RCM), which is carried out by a thin disk cutter, but in the conditions of continuous profile generation, as it is in gear cutting with a hob. It has been shown that due to the peculiarities of this process, its kinematics, and the structure of the disk cutter, RCM is superior to hobbing in all the parameters studied: volumetric productivity, chip thickness ratio, and cutting forces, machining time and machining costs. The higher efficiency of the radial-circular method has thus been demonstrated and the feasibility of its practical application has been confirmed.

ENHANCING MILLING PERFORMANCE OF 6061 ALUMINUM ALLOY WITH NANOCUTTING FLUID AND MQL

During the machining of aluminum alloys, the adhesion of chips to the tool affects the performance characteristics. Today, different cooling systems are used to eliminate these negativities. In this study, the effects of end milling using HSS and carbide cutting tools of 6061-T6 aluminum alloy on surface roughness, chip thickness ratio and tool wear were examined using different cooling techniques (dry, minimum quantity lubrication (MQL) and nanocutting fluid). Different cutting speeds (180, 200, 220 m/min) and different feed rates (0.05, 0.06, 0.07 mm/rev) were used in the experiments. According to experimental findings, tool wear and surface roughness decreased at low cutting speed and feed rate by using nanocutting fluid with carbide cutting tools. It has been observed that the chip thickness ratio increases with high cutting speeds using nanocutting fluid and decreases with dry machining and high feed rates. The best milling performance of the aluminum alloy was achieved in experiments using carbide cutting tools and nanocutting fluid.

Evaluation of tribological interactions and machinability of Ti6Al4V alloy during finish turning under different cooling conditions

The titanium alloy Ti6Al4V has several applications and is considered as a difficult-to-machine material. This study evaluates some tribological interactions in finish turning of Ti6Al4V titanium alloy, including the tool wear, and coefficient of friction in tool-chip interface. Subsequently, the machinability of Ti6Al4V titanium alloy has been investigated, considering the chip geometry, chip thickness ratio, as well as changes in the total cutting force components. The turning process was carried out over a wide range of the feed rate (f) and depths of cut (ap) using hard carbide, GC1115 grade, inserts with double-layer PVD coating. The finish turning tests were conducted under the dry, flood, and MQL (minimum quantity lubrication) cutting conditions. It was found that favorable chip shapes (arc loose) were obtained in the range ap = 0.9–1.2 mm and f = 0.25–0.4 mm/rev. Increasing the f clearly affects the formation of a serrated chip. In addition, the intensity of tool wear, as well as the variations of cutting forces and chip thickness ratios were strongly affected by the applied cooling/lubricating condition. Compared to wet conditions, the Kh values decrease by ∼22 % with dry machining and by ∼12 % with MQL. Compared to wet conditions, for dry machining the cutting forces decrease to 70 % and with MQL to 8 %. The cumulative wear rate under dry machining increases by 18 % compared to wet conditions, and with MQL reduces by 19 %.

Comparison of different 3Y-TZP substrates for the manufacture of all-ceramic micro end mills with respect to the cutting edge radius and the tool wear

In micro milling, size effects such as the ratio of uncut chip thickness to cutting edge radius result to high mechanical stresses. The tools need to be able to withstand these, with as little tool wear as possible. Cemented carbides are currently the tool substrates of choice. Technical ceramics are highly wear resistant as well, but they are not yet used in micro milling. To utilize their potential in micro cutting processes, we previously identified Y-TZP as the best ceramic for this purpose. Compared to cemented carbide, they exhibit only marginal tool wear when micro milling PMMA.To investigate whether the 3Y-TZP characteristics influence the performance of all-ceramic micro end mills, three different substrate materials were used to manufacture tools that were tested by micro milling of PMMA. Further varied factors were the feed per tooth and the spindle speed. The initial cutting edge sharpness of the tools and the tool wear were used to quantify the results. One substrate was found to result in lower cutting edge radii and a more stable manufacturing process than the others. Also, a feed per tooth dependent wear behavior was observed.

Effectiveness of coolant on sustainable drilling and hole quality of titanium alloy

The present research investigated the effects of input parameters such as feed rate, cutting speed and coolant type on sustainability and hole quality during the drilling of Ti-6Al-4V alloy. Several output parameters such as surface roughness, burr height, chip thickness ratio, thrust force, torque and peak power consumption were measured and analysed. Higher cutting speeds (2000 r/min) and lower feed rates (0.04 mm/rev) are recommended to be used to reduce drilling torque (0.77 Nm), thrust force (695 N) and power consumption (0.07 kW). However, it should be noted that increasing cutting speed (2000 r/min) can increase tool tip temperature which is detrimental, particularly for low thermal conductivity materials such as titanium alloys. In addition to that, the effect of tool wear also cannot be negated, as increased tool wear generates more heat in the cutting zone which was not effectively removed due to the poor thermal conductivity of titanium. Liquid nitrogen and chilled air had the greatest influence on temperature reduction at the cutting zone, however, its poor penetration and lubrication properties diminished hole quality. Minimum quantity lubrication conditions proved to strike a balance between good hole quality and enhancing sustainable machining by lowering torque, force and power consumption.

Machinability analysis during finish turning Ti6Al4V with varying cutting edge radius

ABSTRACT The effect of cutting edge radius (rβ) on the chip formation mechanism during the finish turning of Ti6Al4V is studied. An increase in rβ decreases the cutting to thrust force ratio and produces lower chip thickness due to the increase in plowing zone depth. Larger radius tools produce thinner loosely curled chips whereas tightly curled thicker chips are formed for the unprepared edge tool (36 µm). As rβ increases, the chip flow angle (β) increases and free-flowing chips with reduced up-curl but increased side and lateral curl and consequently larger resultant chip curl radius are produced. The chip serration height to overall chip thickness ratio increases whereas chip core thickness reduces owing to the increased plowing action as rβ increases. Chip segmentation analysis reveals increased serration height, thermal instability, and shear localisation in the shear zone due to the increased ploughing effect beyond ~60 µm edge radius.

A theoretical and deep learning hybrid model for predicting surface roughness of diamond-turned polycrystalline materials

Polycrystalline materials are extensively employed in industry. Its surface roughness significantly affects the working performance. Material defects, particularly grain boundaries, have a great impact on the achieved surface roughness of polycrystalline materials. However, it is difficult to establish a purely theoretical model for surface roughness with consideration of the grain boundary effect using conventional analytical methods. In this work, a theoretical and deep learning hybrid model for predicting the surface roughness of diamond-turned polycrystalline materials is proposed. The kinematic–dynamic roughness component in relation to the tool profile duplication effect, work material plastic side flow, relative vibration between the diamond tool and workpiece, etc, is theoretically calculated. The material-defect roughness component is modeled with a cascade forward neural network. In the neural network, the ratio of maximum undeformed chip thickness to cutting edge radius R TS, work material properties (misorientation angle θ g and grain size d g), and spindle rotation speed n s are configured as input variables. The material-defect roughness component is set as the output variable. To validate the developed model, polycrystalline copper with a gradient distribution of grains prepared by friction stir processing is machined with various processing parameters and different diamond tools. Compared with the previously developed model, obvious improvement in the prediction accuracy is observed with this hybrid prediction model. Based on this model, the influences of different factors on the surface roughness of polycrystalline materials are discussed. The influencing mechanism of the misorientation angle and grain size is quantitatively analyzed. Two fracture modes, including transcrystalline and intercrystalline fractures at different R TS values, are observed. Meanwhile, optimal processing parameters are obtained with a simulated annealing algorithm. Cutting experiments are performed with the optimal parameters, and a flat surface finish with Sa 1.314 nm is finally achieved. The developed model and corresponding new findings in this work are beneficial for accurately predicting the surface roughness of polycrystalline materials and understanding the impacting mechanism of material defects in diamond turning.

Study of the finish turning process based on the Parameter Space Investigation method

This paper describes a future-proof Design of Experiment (DoE) method, namely the Parameter Space Investigation (PSI) method. This method reduces the number of test points compared to other DoE approaches, such as single factor design, full factorial design, fractional factorial design, and central composite design, and the number of test points is sufficient for statistical analysis. It allows an efficient analysis of process phenomena, among others, some cutting effects and surface texture forming. It has been shown that in the space of cutting parameters studied, changes in the chip thickness ratio Kh have extreme points, which can be caused by vibration or the build-up-edge formation, and different types of chip shapes are observed. Changes in Kh correlate with chip shapes. In the ranges of depth of cut ap = 0.2 − 1.2 mm and feeds f = 0.05 − 0.4 mm/rev, depending on cooling conditions, the changes in cutting force reach up to 80%. For cutting speeds vc = 50 − 200 m/min and feed rates f = 0.03 − 0.17 mm/rev, the relationships Ra = f(vc,f) are complicated, and the PSI method ensures finding minimum Ra values and areas of physicochemical phenomena. Optimizing the turning conditions over a wide range, at the first stage, the minimum Sa values were obtained in the area of vc = 150 − 300 m/min and f = 0.05 − 0.22 mm/rev, and at the second stage in the areas of vc > 240 m/min and f = 0.03 − 0.07 mm/rev and vc = 100 − 120 m/min and f = 0.01 − 0.13 mm/rev. In addition, the shaping of the machined surface was affected by vc, f, and their interaction. Compared to the first optimization stage, the second stage provided Sa values almost 2 times smaller. It has been proven that the PSI method is effective and can be widely used in various areas of multivariate experimental research and optimization of cutting processes.

CNC Turning of an Additively Manufactured Complex Profile Ti6Al4V Component Considering the Effect of Layer Orientations

Electron beam melting (EBM) is one example of a 3D printing technology that has shown great promise and advantages in the fabrication of medical devices such as dental and orthopedic implants. However, these products require high surface quality control to meet the specifications; thus, post-processing, such as with machining processes, is required to improve surface quality. This paper investigates the influence of two-part orientations of Ti6Al4V EBM parts on the CNC machining (turning) process. The two possible EBM part orientations used in this work are across EBM layers (AL) and parallel to the EBM layer (PL). The effect of the EBM Ti6Al4V part orientations is examined on surface roughness, power consumption, chip morphology, tool flank wear, and surface morphology during the dry turning, while using uncoated carbide tools at different feed rates and cutting speeds. The results showed that the AL orientation had better surface quality control and integrity after machining than PL orientation. Using the same turning parameters, the difference between the roughness (Ra) value for AL (0.36 μm) and PL (0.79 μm) orientations is about 54%. Similarly, the power consumption in AL orientation differs by 19% from the power consumption in PL orientation. The chip thickness ratio has a difference of 23% between AL and PL orientations, and the flank wear shows a 40% difference between AL and PL orientations. It is found that, when EBM components are manufactured along across-layer (AL) orientations, the impact of part orientation during turning is minimized and machined surface integrity is improved.

EFFECT OF THE COOLING WITH AIR AND WATER VAPOR ON MILLING PERFORMANCES

This study aims to investigate experimentally and analytically the effects of different machining parameters such as cooling methods and cutting tool materials on surface roughness and chip thickness ratio for milling of AA7075-T6 aluminum alloy. The carbide and high-speed steel (HSS) end mills were used as cutting tools and the conventional, vapor, and compressed air were used as cooling methods in the experiments. The experiment conditions for compressed air at the cutting zone were 6 bar pressure and 30[Formula: see text]m/s speed flow rate. A mixture of boron oil and water (1/20 mixture ratio) was used as cutting fluid in conventional cooling. The study was carried out using three levels of feed rates (20, 40, 80[Formula: see text]mm/min), rotational speeds (780, 1330, 2440[Formula: see text]rpm), and a constant 2[Formula: see text]mm deep cut. As a result of the experiments, the surface roughness values increased with the increasing levels of feed rate. Besides surface roughness values decreased with increasing levels of the rotational speed. In addition, a better surface quality was obtained in milling processes by using carbide cutting tools compared to HSS tools. It was concluded that the most important parameter affecting the surface roughness and chip thickness ratio is feed rate and the rotational speed, respectively. Better surface roughness and chip thickness ratio were obtained from the vapor processing than the conventional and compressed air.

Evaluation of palm kernel oil as cutting lubricant in turning AISI 1039 steel using Taguchi-grey relational analysis optimization technique

Cutting fluids have a known negative impact on productivity, human health, and the environment in the manufacturing sector. A suitable method for reducing the effect of cutting fluids on human health and the environment is minimum quantity lubrication (MQL). In this experiment, AISI 1039 steel was machined using vegetable oil lubricant and MQL. A chemical method was used to extract vegetable oil from palm kernel seeds. Then, using established techniques, the physicochemical and lubricity properties of palm kernel oil (PKO) were ascertained. The Taguchi L9 (33) orthogonal array served as the basis for the planning of the experimental design. Process parameters such as surface roughness, chip thickness ratio, cutting temperature, and material removal rate were measured during the turning operations. The multi-response outputs from TGRA were considered to simultaneously optimize the cutting parameters namely depth of cut, feed rate, and spindle speed. At a temperature of 55°C, 180 min, and particle sizes of 0.2–0.5 mm, an oil yield of 55% by weight was obtained. The viscosity at 40°C, specific gravity, pour, fire, cloud, and flash points of the raw PKO were 117.6 mm2/s, 0.8940 mg/ml, 21°C, 231°C, 22.3 °C and 227°C, respectively. The surface roughness and cutting temperature of PKO improved by 44% and 12%, respectively, when compared with mineral oil. The findings of this research confirmed the effectiveness of the integrated Taguchi-grey relational analysis (TGRA) optimization method and established an experimental foundation for the use of PKO minimum quantity lubrication turning.

Modeling for prediction of sawing force based on the maximum undeformed chip distribution in the granite sawing

Sawing by circular saw blades is predominant in the mechanized treatment of natural stone. The predictive sawing force is crucial for optimizing, controlling, and monitoring the sawing process. In this work, a novel model for predicting sawing force, which is based on the distribution of the undeformed chip thickness at the sawing contact arc, was proposed. Based on the analysis of the undeformed chip geometry of the circular saw blade, the segment surface was divided into the front end and rear end according to the contact pattern between the segments and granite, and the models of the maximum undeformed chip thickness of diamond particles on the front end and rear end were established. Results showed that the new proposed force model fully considered the distribution of undeformed chips compared with the current model. The novel model has higher prediction accuracy, the mean maximum absolute error is within 3.77%, and the maximum absolute error is within 7.83%. Through theoretical analysis, the ratio of the maximum undeformed chip thickness of the front segment to the rear segment is 1.67, which can fully explain the wear non-uniformity of the segment. The proposed model is of great significance to the optimization of the saw blade structure and process parameters.

Statistical study of surface texture and chip formation during turning of AISI 1020 steel: Emphasis on parameters Rsk, Rku, and Rk family and on the chip thickness ratio

Statistical study of surface texture and chip formation during turning of AISI 1020 steel: Emphasis on parameters Rsk, Rku, and Rk family and on the chip thickness ratio

Crystallographic texture evolutions of Ti-6Al-4V chip foils in relation to strain path and high strain rate arising from large strain extrusion machining process

Large strain extrusion machining (LSEM) is a promising process to create chip foils with ultrafine grains and a certain type of crystallographic texture. Disclosing the interconnection between the deformation histories and the crystallographic texture variations resulting from the LSEM process is vital for the texture generation and control of Ti-6Al-4V chip foils. Electron-backscattered diffraction and viscoplastic self-consistent (VPSC) simulation were combined based on numerical simulation to study evolutions of crystallographic textures for chip foils during LSEM of Ti-6Al-4V. The deformation histories during LSEM process were also analyzed by coupling theoretical analysis with digital image correlation technique. The role of individual type of slip system on the texture variation of Ti-6Al-4V chip foils was identified by modifying the Voce hardening parameters in VPSC model. It is seen that strain path controlled by the chip thickness ratio changes the inclination of generated textures in chip foils. Basal and 1-st order pyramidal <c+a> slip systems are the main deformation modes in high strain rate deformation condition of LSEM process. Similar textures are formed under large strain and high strain rate deformation in LSEM comparing with that in free machining process. The conclusions are useful to control the crystallographic texture generation in LSEM of Ti-6Al-4V by optimizing cutting speeds and chip thickness ratios.

Sustainability in drilling of aluminum alloy

Drilling is an extremely crucial process and enormously used in manufacturing assembling components. On the other hand, the 6061-aluminum alloy is most used in modern industry. Therefore, sustainable drilling of this alloy to reduce the use of power and coolant without compromising the quality is promising for the modern industries. This study investigates the active peak power, burr formation, diameter error, circularity error, cylindricity and surface roughness for different cooling methods such as dry, minimum quantity lubrication (MQL), liquid nitrogen (LN2) and air cooling (AIR) under different speeds and feeds. It is found that cooling methods have negligible effect of active power consumption which increases with the increase of speed and feed. Clear trends of the dimensional errors are not noticed with the variation of parameters considered in this investigation. The influences of coolants on surface roughness and chip thickness ratio also don’t follow any trend. The surface roughness increases with the increase of feeds and speeds. The chip thickness ratio tends to increase with the increase of speed and decrease of feed. It is noted that a specific coolant is required at certain speed and feed to obtain a desired outcome. The balance of hardening and softening effects of workpiece materials at different cutting conditions and rigidity of machine tools controls the desired sustainable outcomes.