Enhancing Tool Life Research Articles

Sustainable machining of additive manufactured SS-316L underpinning low carbon manufacturing goal

Among recent developments in manufacturing industries, the laser-powder bed fusion process (L-PBF) is gaining attention for manufacturing complex and functional parts through the selective melting of powders. However, post-processing is required to improve further the quality of L-PBF parts which corresponds to machinability challenges. In this study, stainless steel grade SS 316L manufactured through L-PBF is subjected to high-speed turning to explore the influence of process variables. The cutting speed, CS (125 m/min, 175 , and 225 m/min), depth of cut, DOC (0.45 and 0.90 mm), and feed rate, FR (0.225 and 0.337 mm/rev) are used for process analysis. Machining performance (surface roughness and tool life) and sustainability aspects (energy consumption, carbon emissions, economics) are taken as response metrics. Parametric optimization to achieve desired response characteristics is carried out. The optimized parametric levels achieved an 87.66% goal of lowering machining cost, 80.94% goal of minimizing carbon emissions, 99.25% goal of decreasing specific energy, 100% goal of enhancing tool life, and 98.95% goal of reducing surface roughness. The present research can be used as a basis for comparative analysis of sustainable machining routes (lubrication-based or production tooling) and as a fundamental guideline for machinists in the metal processing industry.

Hybrid-hybrid turning of micro-SiCp/AA2124 composites: A comparative study of laser-and-ultrasonic vibration-assisted machining

Machining of micro SiCp/AA2124 composites remains a challenge with conventional machining yielding poor surface quality with high tool wear. In this paper, we study two distinct and unique hybrid machining processes with the aim of improving the machining outcome of three types of micro-SiC/AA2124 composites with different particulate volume fractions and sizes. The class of composites studied is available commercially and is being used in industrial applications, thus assessing the machining outcomes becomes even more pertinent. Vibratory machining where the tool is made to vibrate at ultrasonic frequencies, known as ultrasonically assisted turning (UAT), is shown to yield some clear improvements in machining. Next, we incorporate laser assistance with the goal of inducing thermal softening in the process zone. This hybrid-hybrid machining process which is referred to as laser-ultrasonic-assisted turning (LUAT) has the potential for improved machining outcomes with significantly reduced machining forces and surface topology improvement. Our studies indicate that an optimum laser power exists for each type of metal matrix composite considering the particle size and volume fraction of the particulate reinforcements yielding benefits in terms of machining force reduction, surface topology improvement and potentially tool life enhancement. In addition, a computational machining model was developed which can be used to predict the machining outcomes with variable machining parameters.

A Comparative Study on Prediction of Cutting Force using Artificial Neural Network and Genetic Algorithm during Machining of Ti-6Al-4V

The purpose of this comparative study is to improve the predictive accuracy of the cutting force during the turning of Ti-6Al-4V on a lathe machine. By optimizing the machining process parameters such as cutting speed, feed rate, and depth of cut, the cutting force in the machining process can be improved significantly. Cutting force is one of the crucial characteristics that must be monitored during the cutting process in order to enhance tool life and the surface finish of the workpiece. This paper is based on the experimental dataset of cutting forces collected during the turning of titanium alloy under the Minimum Quantity Lubrication (MQL) condition. To predict the cutting forces, two machine learning techniques are explored. Firstly, a black-box model called an Artificial Neural Network (ANN) is proposed to predict cutting force. Using the Levenberg-Marquardt algorithm, a two-layered feedforward neural network is built in MATLAB to predict cutting force. The second model to be implemented was the Genetic Algorithm (GA), a white-box model. GA is an optimization technique which is based on Darwinian theories. It is a probabilistic method of searching, unlike most other search algorithms, which require definite inputs. Using symbolic regression in HeuristicLab, a GA model is developed to estimate cutting force. The anticipated values of cutting forces for both models were compared. Since the ANN model had fewer errors, it was ascertained that the particular model is preferable for machining process optimization.

Experimental tool life and wear analysis of different thickness pecvd TiAlSiN nanocoated cutting tool inserts

Tool life and wear of the coated cutting tools insert play an important role on turning EN24 steel. On turning EN24 steel it is very essential to find the optimum range of coating thickness on the cutting tool inserts with increased tool life and reduced wear. This article investigates the performance evaluation of TiAlSiN-PECVD multilayer nano-coated cutting tool inserts with different coating thicknesses of 1.5, 3, 5, 6.5, 8, 10 and 12 μm.The performance of the cutting tool inserts were evaluated with a cutting speed of 47.12, 54.97 and 62.83 m/min on turning EN24 work material. In the experimental study, the cutting tool inserts with coating thicknesses of 5, 6.5 and 8 µm has given increased tool life and reduced wear where as the coating thicknesses of 1.5, 3, 10 and 12 µm has given reduced tool life and increased wear. The minimum tool wear of 0.124 mm occurred in the coating thickness of 6.5 µm with a cutting speed of 55 m/min. It is observed that the coating thickness ranges from 5 μm to 8 μm has produced an enhanced tool life with corresponding Vickers hardness values ranging from 2400 to 2440 HV. In the comparative study, it has been found that the experimental tool life has enhanced by 19.18%, 31.60% and 20.18% for the corresponding coating thicknesses 5, 6.5 and 8 µm respectively when compared with their theoretical tool life.

Nature-inspired texture pattern for cutting tool tribological surface modification: A state of art

Today, nature inspired textures have gained the attention in various applications in biomedical, biotechnology, medical, marine vehicle design, sports suit design, textile industries, etc. Nature inspired texture (NIT) is also employed in machining application specifically cutting tool industries as pattern/textures for enhancing the tribological properties such as wear, friction and lubrication. The performance of cutting tool in machining condition is fully depends on its tribological properties and can be achieved through surface texturing method only. In the literature (2013 to 2021), various studies have done on texturing for increasing the tribological properties of cutting tool but it results in improper dimensions, more adhesion, high wear, etc. To overcome the existing issues in machining conditions, NIT patterns can be the promising technique for improving the tribological properties. In this direction, in present paper an attempt has been made to identify the Nature Inspired Texture Patterns (NITP) and its effect on tribological performance of machining conditions specifically cutting tool through exhaustive literature from 2013 to 2021. The review has been done in three segments: a) types of NITP & its Selection b) generation of NITP & c) machining applications of NITP. The summary of the literature shows that, ∼30% of friction reduction & enhancement of tool life were recorded.

Electroplastic friction stir spot welding for joining AA6061-T6 aluminum to galvanized DP590 steel

The friction stir spot welding has shown great potential for joining low-ductility aluminum to high-strength steels. In the last decade, wide researches were done to achieve high strength and tool life enhancement in friction stir spot welding. The electroplastic effect, with its environmentally friendly nature and high efficiency, has resulted in a reduction of flow stress and tool wear, improvement of plasticity and material flow for various processes. On the other hand, adding nanoparticles to the friction stir spot welded area joint increased the tool wear despite the improved strength. In this paper, the joint strength and spindle output power are investigated in electroplastic friction stir spot welding process for joining of AA6061-T6 with 1 mm thickness to DP590 steel sheet of 1.5 mm. A 2K design was used for statistical analysis considering four parameters of rotational velocity (1000, 2000 rpm), dwell time (2, 4s), electrical current (250, 500A), and adding SiC reinforcing nanoparticles. A quantitative study of the current density was performed by the finite element code with thermal-electric coupling. Results showed that electroplastic effect had a compatible impact with nanoparticles on strength improvement by accelerating the occurrence of dynamic recovery and recrystallization, and neutralized the negative effect of nanoparticles on tool life since created joints with failure loads above 7 kN.

FEM SIMULATION ASSESSMENT OF MACHINING TITANIUM GRADE 2 USING TEXTURED TOOL

This work focuses on the 3D numerical investigation of machinability criteria using textured tools for the dry machining of titanium grade 2. For the development of the 3D finite element model, DEFORM-3D (version 10.1) software was used. Dimple patterns were created nearer to the cutting edge region on the rake face of carbide inserts so as to predict their effect and investigate the machinability criteria. Comparison of dimple-textured tool was being made with a conventional tool based on the cutting forces ([Formula: see text], [Formula: see text] and [Formula: see text], cutting temperature, tool wear, effective stress and effective strain. The numerical study revealed that the dimple-patterned tool improved the machinability of titanium grade 2. The cutting forces (tangential cutting force, feed force and radial force) reduced while machining with a dimple-patterned tool as compared to the conventional nontextured tool. There was an enhancement of tool life and a decrease in effective stress and effective strain while dry turning grade-2 titanium alloy using the textured tool.

Novel ultrasonic horn design for machining advanced brittle composites: A step forward towards green and sustainable manufacturing

Ultrasonic assisted machining is a proven green and sustainable manufacturing technology owing to low power consumption, no/low usage of lubricant, pollution free nature of the process, excellent machining quality and enhanced tool life. Performance of ultrasonic assisted machining system greatly depends on the amplitude of vibration of the tool, achieved through an ultrasonic horn, design of which is a main interest of researchers. Higher vibration amplification helps achieve good machining quality, minimizes wastes and produces dust free environment. In current research work, novel ultrasonic horn has been deigned to achieve higher vibration amplitude at tool end for ultrasonic machining of advanced brittle composites. 3rd order polynomial equation was used to define horn profile, having resonant frequency closer but greater than generator’s excitation frequency for high magnification factor. Modal and harmonic analyses were carried out to compute axial modal frequency, vibration amplitude, magnification factor and stresses numerically. Performance of newly designed ultrasonic horn was observed to be much better than that of state of the art of standard horn designs in terms of vibration amplification within safe working stress limits. With the same dimensions, the results were compared and found to be in good agreement with the past research. The magnification factor for novel horn design was observed to be 77.56% and 62.73 % higher as compared to that of step and 3rd order Bezier horns. Gaussian horn was also found to provide high vibration amplification when designed with axial modal frequency greater than the generator frequency. • Evaluates standard ultrasonic standard horn designs for machining advanced brittle composites. • Proposes a novel ultrasonic horn design to achieve higher vibration amplification. • Evaluates ultrasonic horns at axial modal frequency greater than generator frequency. • Highlights merits and demerits of ultrasonic horns for frequency ratio less than 1. • Offers recommendations for future work.

Study of the Effects of Initial Cutting Conditions and Transition Period on Ultimate Tool Life when Machining Inconel 718.

Rapid tool wear and limited tool life are major problems when machining Inconel 718, which still need further attention. Amongst the reported strategies, limited studies have been reported on optimizing initial cutting conditions by means of tool life improvement. Therefore, in this work, the tool wear progress and tool life were investigated by varying the initial conditions in the transition period, which was set at four seconds. The transition point was discovered by previous works by the authors. After the transition point, similar cutting conditions were used as the reference condition. The tool wear morphology and size were recorded and analyzed in each condition. It was revealed that applying a lower cutting speed and feed rate in the transition period led to improved tool life as compared to the reference condition. In other words, the use of optimum levels of cutting parameters in the transition period of the cutting process may enhance tool life at higher cutting time. For instance, initial feed rate (0.15 mm/rev) and cutting speed (25 m/min) led to the improvement in the ultimate tool life by about 67% and 50%, respectively. Besides, applying the lower initial cutting speed, i.e., 25 m/min, increased the tool life by about 50% when the insert reached the maximum flank wear (vBmax) of 300 µm in comparison with those at higher initial cutting speeds. This phenomenon may lead to better insight into the effect of the influence of the initial cutting conditions in the transition period on tool life when machining hard-to-cut materials. Moreover, the built-up edge (BUE) was exhibited as the primary wear mode in all cutting conditions.

Machining Behaviour, surface integrity and tool wear analysis in environment friendly turning of Inconel 718 alloy

Manufacturing industries strive for the low toxic and environment friendly machining set up to combat climate change. This research article addresses the machining performance, surface integrity, tool and chip morphology analysis of Inconel 718 in an eco-benign environment, i.e., Atomized Spray Cutting Fluid (ASCF) machining. The process parameters of the machining to evaluate the surface roughness (Ra) were optimized using Response Surface Methodology (RSM). The results revealed that ASCF Machining significantly reduced the vibration acceleration about 14–29% compared to dry machining. ASCF machining experienced very less vibration acceleration at higher cutting speed and feed rate due to the less accumulation of chips in comparison with dry machining. Improved surface roughness in the range 17–34% was observed in ASCF machining. ASCF significantly reduced the tool wear in terms of abrasion and notch wear. The reduction was mainly due to the lubrication effect of spray coolant and reduced cutting temperature in the tool–chip interface. The effective lubrication also attributed to the enhanced tool life in ASCF machining as compared to dry machining.

RETRACTION NOTICE: Development of a dual-layered diamond-coated WC–Co cutting tool for enhancing tool life in the dry machining of mild-steel alloy

RETRACTION NOTICE: Development of a dual-layered diamond-coated WC–Co cutting tool for enhancing tool life in the dry machining of mild-steel alloy

Die Design Architecture for Enhancing Tool Life Via Manipulation of the Elastic Strain Field of the Dies During Extrusion Processes

AbstractForging and extrusion tools are often subjected to a combination of cyclic thermo-mechanical, chemical, and tribological loads. Strategies for minimizing these loads are critical for preventing premature tool failure and increasing productivity. A die design architecture for extrusion that minimizes the residual contact pressure at the die-workpiece interface during the ejection stroke is proposed. The underlying principle of this die design is that during the extrusion stroke, a tapered die can move in the direction of the extrusion load, thus inducing negative radial elastic strain on the die. When the extrusion load is removed, the elastic strain energy stored in the die is released, thus repositioning the die to its initial state. With this design architecture, the workpiece can be ejected at no load. The process was validated using finite element (FE) warm forging/extrusion simulations for a constant velocity (CV) joint and pinion gear shaft. These simulations showed that in addition to reducing residual contact pressure, which enhances tribological conditions, the new die design can easily lower die stresses, thus increasing die fatigue life. The FE simulations for CV joint and pinion gear shaft demonstrated residual pressure in certain locations of the die ranging from 30% to 100% of the pressure induced during the extrusion stroke. The case studies simulated showed that a total energy saving of up to 15% can be achieved with the proposed die setup.

Studies on cryogenically treated WC-Co insert at different soaking conditions

ABSTRACTTool wear and tool replacement significantly increases the machining time and subsequently increase the production cost. To enhance tool life, various surface modification techniques are adopted such as nitriding, hard coating, heat treatments, cyaniding, etc. In the present study, the tungsten carbide-cobalt (WC-Co) cutting tool is treated cryogenically at −196°C with the different soaking periods of 24, 48 and 72 h. The performance characteristics of the treated cutting tool are measured on Al6063 under turning operation at various machining conditions and the results are compared with untreated tools. An experimental design with Cutting velocity, depth of cut and feed rate as machining parameters have been evaluated, with roughness and tool wear rate as the output variables of the study. Minimum tool wear and acceptable level of surface finish are observed on cryogenically treated inserts and Al6063, respectively. An increase in the soaking period in a deep cryogenic environment leads to having excess tool wear and subsequently affects the surface finish. Twenty-four hours and 48 h deeply cryo-treated insert exhibits fine microstructural observation which reveals the formation and distribution of η carbide particles, in turn, results in improved hardness and wear resistance. The conformity of the above results is ensured through Vickers micro-hardness and surface morphological studies.

Comparative Study of some Machining Characteristics during Hard Turning of Alloy Steel with Untreated and Cryotreated Cermet Inserts

Enhanced tool life of cutting inserts are most suitable condition for higher productivity of a manufacturing industry. Several methods are found and employed for higher tool life of cutting inserts among which cryogenic treatment is considered as the most significant method but no adequate researches have been found concerning the impact of cryogenic treatment on cermet inserts especially in hard turning operation. Hence, in the current experimental investigation, the comparative assessment of various responses such as flank wear, crater wear, chip morphology, and chip compression ratio were carried out during machining of hardened steel with both untreated and cryo-treated cermet inserts under dry cutting condition. Wear on the rake faces and flank faces were studied using advanced optical microscope, while chip morphology was studied using SEM. The experimental result demonstrated that the uncoated deep cryotreated with tempered cermet insert delivered better results in comparison to other cermet inserts. Deep cryogenically treated with tempered insert was found to be more suitable during machining of hardened steel because of the enhancement of wear resistance, micro hardness and toughness.

Enhancing Tool Life and Surface Finish by Supplying Cool Air in Dry Machining of MS and AISI-202

Enhancing Tool Life and Surface Finish by Supplying Cool Air in Dry Machining of MS and AISI-202

Enhancing tool life, and reducing power consumption and surface roughness in milling processes by nanolubricants and laser surface texturing

In this study, the effect of applying two different laser surface texturing (LST) patterns to cutting tools, as well as adding nanoparticles (NPs) to a lubricating cutting fluid in a machining process carried out in a Computer Numerical Control (CNC) machine were analyzed. Commonly, machining operations involve high wear of cutting inserts that limit their useful life, provide a poor surface finish of the workpiece and high energy consumption of the process, all of which increase production costs. The texturing patterns proposed were micro-circles and micro-channels and were applied on the rake face of the cutting tools. The NP selected for this study was a montmorillonite nanoclay (MMT) due to its ability to be produced naturally, and for being inexpensive and environmentally friendly. A concentration of 0.13 wt% was used for preparing the nanolubricant cutting fluids. An AISI 1018 steel was selected for the milling experiments at fixed machining parameters. The response variables investigated were: spindle load (related to power and energy consumption of the milling process), radius of the cutting insert (related to wear of the tool), and surface roughness of the steel plates (related to surface quality). The statistical and graphical analyses showed that for spindle load an improvement of up to 11% was found when LST of micro-channels and NPs where combined, whereas no effect was found when they were applied separately. For surface roughness, using tools with textured micro-channels or adding NPs to the cutting fluid were both beneficial individually. In the case of cutting insert radius both micro-circles and micro-channels reduced wear by 64% and 55%, respectively, compared to no LST. The results obtained in this study demonstrate that there is a synergistic effect found when combining LST patterns on cutting tools and adding NPs to the lubricant that increases the efficiency of the milling processes by reducing wear of the cutting tool, improving surface finish, and lowering spindle load.

SPH/FEM modeling for laser-assisted machining of fused silica

Laser-assisted machining (LAM) is a promising technology for the machining of difficult-to-cut materials with reduced cutting forces, improved surface finishing, and enhanced tool life. Smoothed particle hydrodynamics (SPH) method is used to study the cutting mechanism during the laser-assisted machining of fused silica. In the present study, a 3-D transient thermal model is initially proposed to predict the temperature field distribution in the cutting zone of the fused silica. A Fortran subroutine is developed to simulate the moving laser with the Gaussian distribution. Both simulation and experiment results indicate that the thermal model produces an accurate prediction of the temperature in the workpiece. Then, temperature distributions are taken as the initial condition to establish the thermo-mechanical coupled cutting model. The dynamic cutting process is visualized in the cutting model. Moreover, discontinuous and continuous chips are found in both simulation and experiment. It implies that the cutting mechanism works under a hybrid mode of brittle fracture and plastic deformation in the LAM process. The variation of effective stress and plastic strain with temperature is analyzed in the cutting process. It is found that the application of the laser heating remarkably reduces fluctuations of the cutting force. Then, simulated cutting forces are evaluated experimentally. Comparisons show that simulated forces have excellent agreement with those from the experiment. It is concluded that localized high temperature originating from the laser significantly improves the machined surface quality.

An IoT Architecture for Automated Machining Process Control: A Case Study of Tool Life Enhancement in Turning Operations

Abstract With the advent of the Internet of Things (IoT) in manufacturing applications, current research is aimed at utilization of IoT data for process control. This article presents a novel approach to performing automated process feedback using a cloud-based IoT architecture. Specifically, a case study of automated spindle speed adjustment to enhance tool life in a machining operation is used to evaluate the proposed architecture. A data-driven model of tool flank wear evolution in a longitudinal turning operation is created on a cloud-based platform through measurements of a polyvinylidene fluoride thin film sensor voltage data and machine tool parameters monitored via MTConnect. The data are used to develop a Gaussian process regression (GPR) model to predict the average tool flank wear as a function of the measured quantities, which is then used to predict the remaining tool life. The performance of the GPR model is evaluated using 10-fold cross-validation and is shown to be sufficiently accurate for predicting the average flank wear with the coefficient of determination (R2) and the root mean square error values of 0.96 and 13.45 μm, respectively. A web application running the GPR model on the cloud platform is used to forecast the remaining tool life during a turning operation and when the predicted remaining tool life is less than desired, the web application commands a spindle speed override to automatically extend tool life. The architecture is demonstrated through longitudinal turning experiments on stainless steel 316L to extend tool life by 82 %. In addition, the latency of the architecture is evaluated and shown to be acceptable for the tool life enhancement application considered in this study.

In-situ material classification in sheet-metal blanking using deep convolutional neural networks

Sheet-metal blanking is a class of metal fabricating processes that separate a metal workpiece from a primary metal sheet through a shearing process. Industry experts observe fluctuations in tool life and product quality, which is associated with fluctuations in microstructural parameters between and along material coils. With a methodology, that provides reliable information about the current material state in situ through a non-destructive testing method, process parameters, such as forces, speed, and lubrication could be adapted accordingly. This would enhance the productivity of sheet-metal blanking processes or other sheet-metal forming processes with a high process adaptability. The findings of this paper suggest that fluctuations of microstructural parameters along a material coil follow a pattern that is detectable for ferromagnetic materials using magnetic barkhausen noise emission. The preprocessed signal of 18 specimens stemming from six different coils have been encoded to recurrence plots and classified with a deep convolutional neural network with regard to the position on the coil that the respective specimen stem from. The neural network was able to reliably distinct between the recurrence plot of a specimen stemming from the beginning, the middle, or the end of a material coil. Through an advanced labelling approach and classifying for specific microstructural parameters, the same methodology could possibly be used to detect certain material states and quality deficits and to adjust the sheet-metal blanking process accordingly to enhance tool life and product quality.

Wear and surface roughness analysis of machining of Ti-6Al-4V under dry, wet and cryogenic conditions

Use of cooling media contributes in elevation of desired responses owing to its cooling and lubrication effects especially in case of hard to cut materials like Ti-6Al-4V. This study aims to analyze the effect of cooling media in addition to cutting speed on responses including tool wear and surface integrity during turning. Results highlighted the effectiveness of cooling system in particular that of cryogenic media. Use of cryogenic media and cutting fluid enhanced tool life max by 33% and 21% respectively. At lower cutting speed surface roughness was improved by 13% and 8% by cryogenic media and cutting fluid respectively.