Application Of Minimum Quantity Lubrication Research Articles

Minimum Quantity Lubrication (MQL) Supply through Internal Cooling Channels in Drilling Processes

Minimum quantity lubrication (MQL) technologies possess great potential for improving the sustainability of manufacturing processes, which can reduce the absolute quantity of metalworking fluid (MWF) and also enable near-dry chips that are easier to recycle. During drilling in particular, the MWF is transported to the contact zone through internal cooling channels of the drilling tool. The MWF supply and its associated flow behaviour in the transfer from the outlet of the cooling channels to the contact zone have not been sufficiently investigated yet. Great potential is seen in the proper delivery of the MQL into the contact zone. This work aims to visualize and quantify the cooling lubricant supply into the cutting zone using the MQL technique. The visualization of the MQL application is made possible by high-speed shadowgraphic imaging. Detailed image processing is used to evaluate the resulting images. The developed evaluation routine allows for the assessment of the impact of the main process parameters such as the varying pressure of the aerosol generator and the cooling channel diameter. It is found that the oil leaves the cooling channels at the tip of the drill bit in the form of ligaments. An increase in pressure and cooling channel diameter leads to an increase in the frequency of oil ligament separation. Three main flow regimes are identified with different separation frequencies. Low inlet pressures result in intermittently dispersed droplets. The most upper pressure levels lead to an almost continuous dispersion of the oil. At the same time, the air and oil mass flow rates also increase.

Towards sustainable manufacturing: Multiple optimization of surface roughness Ra, flank wear Vb in MQL-assisted milling of Titanium Alloy Ti-6Al-4V

This research focuses on the sustainable optimization of the milling process for Titanium Alloy Ti-6Al-4V using Minimum Quantity Lubrication (MQL) assistance. This experimental research investigates the effects of cutting parameters and lubrication conditions on the surface roughness ([Formula: see text]) and flank wear ([Formula: see text]) in the milling process of Titanium Alloy Ti-6Al-4V. The study aims to evaluate the influence of cutting speed ([Formula: see text]), feed rate ([Formula: see text]) and depth of cut ([Formula: see text]) on the selected machining performance indicators. The experiments were carried out using a DMG Mori Seiki DMU50 CNC center, and the workpiece samples were measured at [Formula: see text]. Three different lubrication conditions were employed, including dry machining, conventional flood cooling and Minimum Quantity Lubrication (MQL) using peanut oil. The cutting parameters were varied based on a Taguchi L9 orthogonal array design to explore the main effects of each parameter on [Formula: see text] and [Formula: see text]. The results reveal that cutting speed ([Formula: see text]) has the most significant influence on surface roughness, followed by feed rate ([Formula: see text]), while the impact of depth of cut ([Formula: see text] is negligible in comparison. Conversely, the coolant mode has the most significant impact on flank wear ([Formula: see text]), followed by feed rate ([Formula: see text]) and depth of cut ([Formula: see text]), while the influence of cutting speed ([Formula: see text] is relatively minor. Under the same cutting parameters, transitioning from dry machining to MQL led to a sharp decrease in [Formula: see text] from 170 to 100[Formula: see text][Formula: see text]m, and it increased to approximately 145[Formula: see text][Formula: see text]m when switching to flood cooling. Additionally, increasing the feed rate from 0.02 to 0.06[Formula: see text]mm/tooth reduced [Formula: see text] from around 135 to 120[Formula: see text][Formula: see text]m, but it significantly rose to approximately 165[Formula: see text][Formula: see text]m when the feed rate was further increased. Furthermore, the application of MQL with peanut oil as a lubricant and coolant demonstrated improvements in surface finish and reduced tool wear compared to dry and conventional flood cooling. The MQL approach led to better machining performance with lower [Formula: see text] and [Formula: see text] values. Overall, this study provides valuable insights into the effects of cutting parameters and lubrication conditions on surface roughness and flank wear in the milling process of Titanium Alloy Ti-6Al-4V. The findings offer practical guidelines for optimizing machining conditions to achieve desired surface quality and extend tool life while considering the environmental benefits of employing MQL in the manufacturing process.

Prediction and classification of tool wear and its state in sustainable machining of Bohler steel with different machine learning models

Machine learning has numerous advantages, especially in the rapid digitization of the manufacturing industry that combines data from manufacturing processes and quality measures. Predictive quality allows manufacturers to make informed predictions about the quality of their products by analyzing data gathered during production. The quality of the machining, the total cost and the computation time need to be improved using contemporary production processes. With this concern, a series of experiments were carried out on Bohler steel both in dry, Minimum Quantity Lubrication (MQL) and nano-MQL conditions in varying quantities to explore the tool wear. In comparison to dry conditions, the utilization of MQL in machining processes demonstrates significantly enhanced efficacy in mitigating flank wear. The reduction in flank wear ranges from around 5% to 20% to 25%, contingent upon the application of MQL on the flank face, rake face, or both faces simultaneously. After that, the results of the tests were evaluated with the models of machine learning (ML) to determine which environment was optimal for cutting under both real and artificial circumstances.

Investigation on cutting performance in ultrasonic assisted helical milling of Ti6Al4V alloy by various parameters and cooling strategies

Ti6Al4V alloy is one of the typical difficult-to-machine materials and often results in rapid tool wear, leading to poor machining quality in aircraft assembling. Compared to conventional helical milling, the ultrasonic assistant helical milling (UAHM) process has indicated its superior performance; however, it is still a great challenge to improve the hole surface quality and accuracy. In addition, few studies have been conducted on the effect of different variables and cooling strategies on the hole-making performance in longitudinal-torsional ultrasonic assisted helical milling (LT-UAHM). This paper, for the first time, reports effects of machining variables on geometric precision and surface roughness in LT-UAHM of Ti6Al4V. In addition, the lubrication/cooling mechanism on the simultaneous application of LT-UAHM and MQL is theoretically analyzed. The design approach of Taguchi experiment was employed to study how major variables such as the cutting speed, tangential feed, axial feed, and the workpiece hardness influence the dimensional and geometrical tolerances and surface roughness. This paper also discussed the effect of three cooling strategies, i.e., dry condition, air coolant, and minimum quantity lubrication (MQL) in LT-UAHM. Theoretical analysis demonstrated that the MQL coolant can be nebulized into hyper-fine droplets owing to the resonant cavitation phenomenon. Combined with the penetrating action caused by the separate-cutting principles of LT-UAHM, the cooling and lubrication performance of MQL was further enhanced. As a result, LT-UAHM with MQL had the most positive effect on circularity, cylindricity, nominal diameter, and surface roughness, contributing to 34%, 32%, 39%, and 40%, respectively. The second important machining factor was the cutting speed, contributing to 31%, 29%, 36%, and 22%, respectively. The tangential feed and workpiece hardness have the negative effect on geometrical accuracy, respectively.

Experimental study of MQL applicability in ADI grinding and its influence on surface topography

ABSTRACT When workpieces require tight tolerance or a good surface finish, grinding is usually the best solution. Yet this process is characterised by generating a great amount of heat that needs to be controlled. The minimum quantity lubrication (MQL) system emerged as an alternative to the flood cooling system. Nevertheless, the employment of the former in austempered ductile iron (ADI) surface grinding is still an unexplored topic. This research seeks to experimentally study the applicability of MQL and the influence of the wheel speed and workspeed, in the surface topography of ADI samples subjected to different conditions of surface grinding. ADI surface topography was acquired, then the roughness parameters and surface hardness alterations were determined. The results show that the application of MQL in ADI surface grinding is possible. The surface roughness is similar to that of the flood cooling system and the surface hardness alterations are small.

Assessment of sustainable dry and MQL-assisted hard machining using MTCVD multilayered coated carbide (TiN/TiCN/Al2O3) insert

ABSTRACT The application of minimum quantity lubrication (MQL) provides cooling, chip flushing and environment-friendly functions for sustainable manufacturing. Thus machinability study and surface characterisation of hardened AISI 4340 steel have been performed through multilayered coated MTCVD carbide (TiN/TiCN/Al2O3) insert under different cutting environments i.e. dry and MQL for sustainable machining. Flank wear in both cases (dry and MQL) is within the 0.2 mm failure criterion. Cutting speed influences more on flank wear more under dry conditions (65.26%), whereas depth-of-cut is for MQL (69.10%). Feed rate is the most significant parameter for surface roughness i.e. 73.40% and 75.96% contribution under dry and MQL, respectively. Average absolute errors for both artificial neural network (ANN) and regression models lie within 5%, with ANN giving better predictions. At 0.1 mm depth of cut, 0.04 mm/rev feed rate and 50 m/min cutting speed, tool life is 176.55 and 217.16 min (23% greater) in dry and MQL, respectively. In another condition of 0.1 mm depth of cut, 0.04 mm/rev feed rate and 100 m/min cutting speed, tool life under dry and MQL is 80.2 min and 131.2 min which contributes 63.6% greater than dry condition. MQL enhances the tool life and improves machinability and contributes towards sustainability.

Impacts of Surface Texture and Nature of Friction on Energy-Force Efficiency of Surface Plastic Deformation during Burnishing

Burnishing, the plastic deformation of the workpiece surface due to sliding contact with a tool called burnisher, is a finishing operation widely used in various industries. In this work, impacts of the initial surface roughness Ra of the workpiece being burnished, the nature of friction in the contact zone, and the clamping force on the stability and energy efficiency of burnishing have been investigated. Experiments have been conducted with and without lubricant, represented by low-viscosity deep-hydrogenated fraction of sour oils, at initial surface roughness Ra of 0.8 and 1.25 μm and variable (100–200 N) clamping force. A key process indicator, which largely controls mechanics of burnishing, the temperature in the tool-workpiece contact zone has been measured using natural thermocouple method. Microhardness of the workpiece surface after burnishing has also been measured. It has been shown that changes in the temperature of the tool-workpiece contact zone are proportional to the changes in the squared tool clamping force. This dependence appeared to be universal and equally applicable to burnishing with and without lubrication. Based on the analysis of the experimental data, a new criterion of the burnishing efficiency has been developed. The new criterion simplifies the choice of optimum operational parameters and helps in preventing adverse impacts of structural phase transformations in the workpiece surface layer that unavoidably lead to reduced product quality and operational reliability and in reducing tool wear, which is critically important in the case of dry burnishing. The obtained results show that the nature of friction accompanying the surface plastic deformation has a significant impact on the stability and energy efficiency of the burnishing process. While the clamping force is equally important for burnishing with and without lubrication, the initial roughness Ra has an impact on dry burnishing only. Application of minimum quantity lubrication (MQL) under experimental conditions typical for industrial burnishing is found to be favorable. In particular, it was shown that MQL not only enhances the stability of burnishing process and but also increases its energy efficiency by more than 20%.

Wear of micro diamond tool in ultra-precision turning under dry and minimum quantity lubrication conditions

Minimum quantity lubrication (MQL) is an effective way to reduce the cutting temperature and tool wear. To reveal the effect of MQL on the wear of micro diamond tool, a calculation model for the cutting temperature of micro diamond tool under dry friction condition is established firstly by using the Fourier’s law of heat conduction. Regarding the boundary film as a layer of heat-conduction medium, a revised calculation model for the temperature distribution on tool rake face under MQL condition with different cutting fluids is further established. The predicted results indicate that low viscosity is beneficial to the wetting of cutting fluid on tool-chip contact interface, which can relieve the friction. The reduction of friction finally decreases the cutting temperature. Secondly, the cutting temperature–dependent wear volume of micro diamond tool is predicted by using the Usui wear rate model in response to different cutting fluids and different cutting distances. In dry cutting, the graphite wear of micro diamond tool prevails. However, the application of MQL can slow down the graphitization of diamond, so the wear of micro diamond tool visibly decreases. Finally, cutting experiments with different cutting fluids are performed to verify the established models. The experimental observations agree well with the theoretical prediction results. Such satisfactory consistency confirms that the cutting fluid with low viscosity can reduce the cutting temperature and inhibit tool wear effectively.

Influence of grinding parameters on surface roughness and temperature under carbon nanotube assisted MQL

ABSTRACT Conventional flood cooling system has some environmental and economic issues. Minimum quantity lubrication (MQL) has been established as a better strategy to control the machining temperature than conventional flood cooling system. Integrated use of carbon nanotube (CNT) with MQL has been drawing attention in recent times. The purpose was to study the effects of hard grinding with key focus on temperature, surface roughness and chips morphology under the application of CNT-mixed MQL and compressed air. The hardness of work material (AISI 1060 steel) was varied at three values (40, 45 and 50 HRC) with the variation of fluid flow rates and infeed rates to observe the machining behaviour. Experimental plan was established using full factorial design of experiment while mathematical models and optimisation were constructed following response surface methodology (RSM). Optimum output responses were flow rate 75 ml/h, infeed (depth of cut) 10 µm and hardness of material is from 40 to 45 HRC. Fluid flow rate of 75 ml/h resulted in best surface finish while work material of 40 HRC hardness generated lowest temperature while machining. A lower hardness values and a moderate flow rate produced favourable machining outcomes, i.e. lower temperature and improved surface finish.

Analytical Model for Temperature Prediction in Milling AISI D2 with Minimum Quantity Lubrication

Milling with minimum quantity lubrication (MQL) is now a commonly used machining technique in industry. The application of the MQL significantly reduces the temperature on the machined surface, while the cost of the lubricants is limited and the pollution caused by the lubricants is better controlled. However, the fast prediction of the milling temperature during the process has not been well developed. This paper proposes an analytical model for milling temperature prediction at the workpiece flank surface with MQL application. Based on the modified orthogonal cutting model and boundary layer lubrication effect, the proposed model takes in the process parameters and can generate the temperature profile at the workpiece surface within 1 min. The model is validated with experimental data in milling AISI D2 steel. With an average absolute error of 10.38%, the proposed model provides a reasonable temperature prediction compared to the experimental results. Based on the proposed model, this paper also investigates the effect of different cutting parameters on the cutting temperature. It is found that the application of the MQL decreases the temperature at the cutting zone, especially at the flank surface of the workpiece, which is due to the heat loss led by air-oil flow.

Shadow zone in MQL application and its influence on lubricant deficiency and machinability during micro-milling

Minimum quantity lubrication (MQL) in metal cutting helps enhancing machinability while ensuring sustainability. In the absence of bulk heating in micro-milling, the cutting fluid needs to be deposited on the tribologically active chip-tool-workpiece region to perceive enhanced lubrication effect. There are few factors that can restrict the oil droplets from depositing on the tool. One such restriction that inherently appears as “Shadow Zone” during end-milling process is reported in this article for the first time. This shadow zone hinders certain percentage of droplets from reaching to the cutting edges resulting in reduced wetting capability of the MQL supply even when the overall oil flow rate remains unchanged. Lubricant deficiency induced solely by this shadow zone during micro-milling under varying parameters is assessed here. For fixed nozzle orientation, detrimental effect of the shadow zone intensifies with an increase in the axial depth of cut and top-burr height. At 50 µm axial depth, the shadow zone restricts 3.7% droplets from depositing on the active cutting edge and thereby compels the MQL assisted cutting process to rotate in incompletely lubrication condition. For unchanged oil flow rate, the corresponding deficiency increases to 16.4% at 200 µm axial depth. When compared with dry micro-milling of Ti-6Al-4 V, shadow zone reduces effectiveness of the MQL supply in controlling tool wear from 25.4 – 5.5% in the entire tool life when axial depth is increased from 50 – 200 µm. Similar degree of reduction in MQL effectiveness towards controlling surface roughness, burr width, and cutting forces is also observed.

Analytical modeling of residual stress in end-milling with minimum quantity lubrication

Milling with minimum quantity lubrication (MQL) is now a commonly used machining technique in industry. This paper proposed an analytical model for residual stress prediction in milling with MQL based on chip formation orthogonal cutting model and boundary lubrication effect. The effect of lubrication is considered to the change of friction coefficients and the heat loss at the flank surface, which would further affect the prediction of the cutting force and temperature. The proposed model is validated with experimental data done to AZ61A magnesium alloy and obtained a reasonable validation result. The predictive results show at the case investigated, neither feed per tooth nor depth of cut has a significant influence to the general trend of residual stress, where at the surface the residual stress is highly tensile and come to compressive at deeper depth. However, the application of MQL is shown to be able to significantly reduce the average magnitude of the residual stress.

Progressive wear based tool failure analysis during dry and MQL assisted sustainable micro-milling

Micro-milling tools suffer high wear rate and early edge-chipping owing to their small sizes. Mechanism of various wear modes of a coated tool with the progression of micro-milling along with the conditions for their onset was not systematically explored in literature. To understand the edge-chipping scenario with the progression of wear, a comprehensive tribological analysis is presented in this article considering the cumulative effects of process mechanics, material deformation mechanism, tool geometry, lubrication, and process parameters during micro-milling of Ti-6Al-4V using 500 μm TiAlN-coated WC/6Co end-mills. The apparent friction coefficient at the chip-tool-workpiece interface remains very high, in the range of 0.97 – 0.84 in dry micro-milling that reduces to 0.60 – 0.50 under sustainable minimum quantity lubrication (MQL). When a fresh tool is engaged, it undergoes rapid wear for initial 15 mm length of cut. Thereafter, the tool undergoes gradual non-adhesive wear for another 40 – 70 mm cut. As the edge radius increases with machining time, the corresponding minimum uncut chip thickness (hmin) also increases proportionally. When hmin exceeds 12% (for MQL) or 34% (for dry) of the set feed per flute, strong adhesion occurs at the cutting edge, and the process is dominated by the non-cutting passes. Normal stresses within the ploughing-dominant region also remain reasonably high (10 – 18 GPa). Initially the coating, and thereafter the adhered layer, helps sustaining such high normal stresses. Once the adhered layer dislodges, the exposed substrate fails to sustain high stresses leading to edge-chipping. As compared to dry micro-milling, application of MQL helps decreasing abrasion rate, assisting in chip-evacuation, discouraging adhesion, and extending the tool-life; however, the same unfavourably increases the intensity of stresses within the ploughing-dominant region making the tool-tip more vulnerable to chipping.

On the improvement in process performance of ceramic inserts during hard turning in MQL environment

ABSTRACT Hard turning process, frequently used to finish the rotational surfaces of hard steel components, has some major issues like a high tool wear rate coupled with the degradation of surface finish and generation of brittle white layer. Due to this, the process productivity also remains low. In an attempt to improve the cutting tool productivity while machining hardened EN31 steel, uncoated ceramic inserts were used with the Minimum Quantity Lubrication (MQL) environment, which resulted in significant wear reduction on the ceramic inserts along with a better surface finish than that produced with a dry cutting. The most suitable process parameters, to produce an efficient cut, i.e., high process performance on both wear and surface finish fronts, were proposed. The surface integrity produced within the process parameter window identified was compared for both dry and MQL environments. It was confirmed that application of MQL brought about a significant reduction in formation of subsurface white layer both at lower and higher feeds (around 40% and 16.5% respectively) when compared to dry mode cutting. MQL condition enhanced the overall productivity of ceramic inserts with lower flank wear and better surface characteristics even at higher feeds, while at the same time, producing a thinner white layer.

Post-processing of 3D printed thermoplastic CFRP composites using cryogenic machining

Additive manufacturing (AM) or three-dimensional (3D) printing allows manufacturing of parts of complex shapes using carbon fiber reinforced polymer (CFRP) composites. However, in many cases, the parts fabricated by 3D printing suffer from poor surface quality and dimensional accuracy, requiring extensive post-processing. This research aims at improving the dimensional accuracy and surface finish of 3D printed CFRP composites by analyzing the effectiveness of three sustainable machining practices: dry, minimum quantity lubrication (MQL), and cryogenic machining, as post-processing techniques for 3D printed CFRP composites. This study specifically investigates effects of printing and machining parameters and cooling/lubricating conditions on the machining performance, i.e., burr formation, surface finish, cutting forces, and tool wear during edge and slot milling of 3D printed thermoplastic CFRP composites. Among three sustainable machining processes, cryogenic machining significantly reduced burr formation and tool wear, and improved surface finish irrespective of the fiber orientation and machining conditions. The application of MQL at the tool-workpiece interface was found to be effective in reducing tool wear, surface roughness, and burr formation to some extent compared to dry machining. However, MQL process was not able to completely eliminate burr formation for most of the machining conditions. Cryogenic machining caused the highest cutting forces due to the increased surface and sub-surface hardness of the workpiece caused by application of liquid nitrogen; however, no adverse effect of increased cutting forces was observed. This study finds that cryogenic machining is able to completely eliminate or reduce burrs by 90% and bring down the surface roughness (Rq) from >10 μm to about 1 μm, thus making it a suitable post-process technique for 3D printed CFRP composites.

Investigating a novel Ag/ZnO based hybrid nanofluid for sustainable machining of inconel 718 under nanofluid based minimum quantity lubrication

Sustainable machining, with implementation of eco-friendly dry and minimum quantity lubrication (MQL) methods, has gained attraction of researchers and engineers to solve the environmental and health allied issues caused by bulk usage of the conventional cutting fluids. Nanofluids have recently became more obvious choice as a cutting fluid in MQL applications owing to their superior thermo-physical properties. In this work, a novel hybrid nanofluid, consisting of Ag coated ZnO (Ag/ZnO) nanoparticles in ethylene glycol base, has been proposed as cutting fluid for MQL application. Initially, the Ag/ZnO hybrid nanoparticles were synthesized by a chemical precursor method. Then, synthesized nanoparticles were blended in ethylene glycol at several volume concentrations (Φ = 0.05 % to 0.2 %). The nanofluids were characterized for their thermo-physical properties and stability criterion, and then a nanofluid with the best performance was selected for nanofluid based MQL (NFMQL) experiments. The performance of NFMQL was compared with dry, MQL environments during milling of difficult-to-cut Inconel 718 superalloy with PVD coated carbide inserts. Taguchi L9 orthogonal array was incorporated for experimental design to investigate the effect of cutting speed, feed rate and machining environment on the machining performance in terms of the average surface roughness and cutting temperature. Analysis of variance shown that the cutting environment contributed to the average surface roughness and cutting temperature by 24.52 % and 44.74 %, respectively. As compared to dry and MQL condition, the NFMQL improved the surface finish by 23.5 % and 13.07 %, respectively, and reduced the cutting temperature by 15.38 % and 8.56 %, respectively, owing to proposed hybrid nanofluids enhanced lubrication and heat dissipation properties. Furthermore, the field emission scanning electron microscopic (FESEM) images of used cutting tool inserts reveal that the NFMQL condition induces the minimum tool wear as compared with MQL and dry environments. Finally, the multi-response optimization was achieved through the implementation of Taguchi grey relational analysis (TGRA) with the optimum combination of cutting speed of 30 mm/min, feed rate of 0.036 mm/tooth, and NFMQL cutting environment.

Quantitative analysis of dispersion, cooling and lubricating properties of graphene dispersed emulsifier oil

All manufacturing sectors use cutting fluids. Need for sustainable manufacturing discourages the application of cutting fluid as flood and encourages their application in small quantity strictly at the cutting zone, i.e., minimum quantity lubrication (MQL). But, MQL application requires development of cutting fluids with augmented properties. Present work performs quantitative analysis of dispersion, cooling and lubricating properties of graphene dispersed emulsifier oil. In the present work, initially 0.1 wt% graphene dispersed emulsifier oil samples are prepared by using different surfactants, sonication times and graphene to surfactant ratios and optimal conditions are identified which showed maximum dispersion stability. Absorbance method is use to evaluate dispersion stability. Use of Triton X100 with graphene to surfactant ratio of 1.5 and sonication time of 60 s is found to be the optimum condition. Properties like density, kinematic viscosity and dynamic viscosity are evaluated and ratio of graphene to surfactant is decided for 0.3 wt% and 0.5 wt% graphene dispersed emulsifier oil. Thermal conductivity and tribological properties are evaluated to quantitatively analyze the cooling and lubricating properties of graphene dispersed emulsifier oil. Emulsifier oil with 0.1 wt%, 0.3 wt% and 0.5 wt% graphene with surfactant Triton X100 added in same ratio as graphene showed enhancement viscosity which is 1.6, 2.6 and 3.4 times the viscosity of base emulsifier oil and also showed good stability. The corresponding thermal conductivities are found to be 1.1, 2 and 1.5 times the thermal conductivity of base emulsifier oil and coefficient of friction is found to decrease by 0.6%, 2.9% and 5.8%, respectively. Good stability, enhanced viscosity, thermal conductivity and reduced coefficient of friction make them suitable for machining applications.

Adhesion of Inconel 718 on Uncoated Tungsten Carbide Inserts in Interrupted Orthogonal Machining under MQL

Nickel-base super-alloys such as Inconel 718 are used for demanding applications in the industry. Their superior corrosion resistance and mechanical properties, especially under high heat and pressure, make them very attractive for highly stressed components. In contrast, their low thermal conductivity, work hardening tendency and high strength impose challenges for machining. In particular, occurring adhesion of the workpiece material on tungsten carbide (WC) inserts and tools is common hindering their life. In order to counteract this undesirable effect, cutting fluids are usually implemented. However, due to increased awareness of cutting fluids negative impact on the operator’s health and the environment, minimum quantity lubrication (MQL) is getting more attention among researchers and in the industry. In this study, the adhesion on the rake face of uncoated WC inserts under the application of MQL is observed. Inconel 718 workpieces prepared for orthogonal cutting trials are interrupted at variable intervals to allow more access for MQL to reach chip-tool interface. Mechanical load, coefficient of friction, adhesion area and chip-tool contact length on the rake face are investigated. It has been observed that interrupted machining can positively influence adhesion area and chip-tool contact length.

Analysis of hybrid nanofluids in machining AISI 4340 using minimum quantity lubrication

Abstract Cutting fluids enhance the machining performance due to their ability to provide good lubrication and remove generated heat. Minimum quantity lubrication (MQL) serves as the best alternative for flood machining as it allows a considerable reduction in machining cost along with longer tool life. Nanofluids are fluids having enhanced lubrication and cooling characteristics due to very high surface to volume ratio of nanoparticles. In the present work, machining is performed in dry condition, MQL application of soluble oil without nanoparticles, 0.3 wt% of copper dispersed in soluble oil, 0.3 wt% of graphene dispersed in soluble oil, and 0.3 wt% of graphene and copper (1:1) dispersed in soluble oil (hybrid nanofluid). Turning of AISI 4340 material is performed using uncoated tungsten carbide at varying cutting parameters. Graphene nanofluid as well as hybrid nanofluid showed the least flank wear. Hybrid nanofluid showed the least cutting temperature at higher depth of cut and higher feed while copper nanofluid showed the least cutting temperature at higher cutting velocities.

Assessment of cryo-MQL environment for machining of Ti-6Al-4V

Titanium alloys are highly resistant to aggressive environment, possess high strength and have lightweight as well as exceptional fatigue endurance. Even with excellent properties, in the industrial scenario, titanium alloys are considered as one of the difficult-to-cut materials. Therefore, a hybrid lubrication/cooling environment is proposed by combining minimum quantity lubrication (MQL) and cryogenic environments for turning of Ti-6Al-4V alloys at heavy machining conditions. Cryo-MQL includes simultaneous application of MQL and liquid nitrogen from two different nozzles at the machining region for better lubrication and cooling. Feed and cutting forces, workpiece surface roughness and microhardness, sliding-sticking regions contact length and tool morphology was assessed for three distinct lubrication/cooling environments; dry, MQL, and cryo-MQL. The assessment indicates a significant improvement in machining performance; cryo-MQL environment shows reduction in machining forces and workpiece surface roughness by 27 % and 46 % over dry environment. Morphology of the tool rake surface shows significant reduction in sliding-sticking regions contact length. Elemental composition confirms the reduction of workpiece material adhesion on the tool rake surface compared to dry and MQL environment.