Lubrication Environment Research Articles

High-speed turning of AISI 4340 alloy steel using carbide tools in a sustainable minimum quantity lubrication environment

Purpose This study aims to investigate the machining performance of CVD-coated carbide tools by considering most crucial machinability aspects: cutting force, tool life, surface roughness and chip morphology in high-speed hard turning of AISI 4340 alloy steel under a sustainable minimum quantity lubrication (MQL) environment. Design/methodology/approach The purpose of this study is to analyze the performance of coated carbide tools under MQL environment therefore, machining tests were performed in accordance with the Taguchi L9 orthogonal array, accommodating the three crucial machining parameters such as cutting speed (V = 300–400 m/min), feed rate (F = 0.1–0.2 mm/rev) and depth of cut (DOC = 0.2–0.4 mm). The measured or calculated values obtained in each experimental run were validated for normality assumptions before drawing any statistical inferences. Taguchi signal-to-noise (S/N) ratio and analysis of variance methodologies were used to examine the effect of machining variables on the performance outcomes. Findings The quantitative analysis revealed that the depth of cut exerted the most significant influence on cutting force, with a contributing rate of 60.72%. Cutting speed was identified as the primary variable affecting the tool life, exhibiting a 47.58% contribution, while feed rate had the most dominating impact on surface roughness, with an overall contributing rate of 89.95%. The lowest cutting force (184.55 N) and the longest tool life (7.10 min) were achieved with low machining parameters at V = 300 m/min, F = 0.1 mm/rev, DOC = 0.2 mm. Conversely, the lowest surface roughness (496 nm) was achieved with high cutting speed, low feed rate and moderate depth of cut at V = 400 m/min, F = 0.1 mm/rev and DOC = 0.3 mm. Moreover, the microscopic examination of the chips revealed a serrated shape formation under all machining conditions. However, the degree of serration increased with an incremental raise with cutting speed and feed rate. Research limitations/implications The study is limited to study the effect of machining parameters within the stated range of cutting speed, feed rate and depth of cut as well as other parameters. Practical implications Practitioners may consider to adopt this machining technique to create more sustainable working environment as well as eliminate the disposal cost of the used metal cutting fluid. Social implications By applying this machining technique, diseases caused by metal cutting fluid to the mechanist will be significantly reduced, therefore creating better lifestyles. Originality/value Hard turning is commonly carried out with advanced cutting tools such as ceramics, cubic boron nitride and polycrystalline cubic boron nitride to attain exceptional surface finish. However, the high cost of these tools necessitates exploration of alternative approaches. Therefore, this study investigates the potential of using cost-effective, multilayer-coated carbide tools under MQL conditions to achieve comparable surface quality. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2024-0013/

Cooling and Lubricating Strategies for INCONEL® Alloys Machining: A Comprehensive Review on Recent Advances

Abstract INCONEL® alloys are Ni-based superalloys with superior mechanical properties for extremely high temperature (T) applications. These alloys present significant challenges: they are difficult-to-cut materials due to the low thermal conductivity (k), severe work hardening and elevated surface hardness. They are widely used in applications that require good dimensional stability; however, built-up edge (BUE) followed by premature Tool Wear (TW) are the most common problems when applying conventional machining (CM) and hybrid machining processes, i.e. Additive Manufacturing (AM) followed by milling, resulting in a meagre final product finishing. Regarding cooling/lubricating environments, a miscellanea of methods can effectively be applied to INCONEL® alloys, depending on their advantages and disadvantages. It is imperative to refine the machining parameters to enhance the performance outcomes of the process, particularly concerning the quality and cost-effectiveness of the product. This current review intends to offer a systematic summary and analysis of the progress taken within the field of INCONEL® CM and the various cooling/lubricating methods over the past decade, filling a gap found in the literature in this field of knowledge. A Systematic Literature Review (SLR) approach was employed in this study, aiming to identify pertinent papers within the cooling and lubricating strategies for INCONEL® alloys machining. The most recent solutions found in the industry and the prospects from researchers will be presented, providing significant insights for academic researchers and industry professionals. It was found that selecting cooling methods for INCONEL® machining requires careful consideration of various factors. Each lubrication environment utilized in traditional INCONEL® machining methods offer unique advantages and challenges regarding the different outcomes: TW, Tool-Life (TL) and/or surface quality assessment; nevertheless, cryogenic cooling by CO2(l) and N2(l) highlights as the better cooling environment to improve the machined surface quality.

Comprehensive analysis of cutting temperature, tool wear, surface integrity and tribological properties in sustainable milling of Ti6Al4V alloy: LN2, nanofluid and hybrid machining

Despite being expensive and difficult to process, the Ti6Al4V alloy is a vital component for crucial industries. To improve its machinability and accomplish sustainable production, environmentally friendly cooling and lubricating agencies are used. Studies on the machinability of the alloy are still necessary because of its unique features and significance in vital industries like aerospace, defense, and medicine. Therefore, this investigation focuses on tool wear, temperature, and surface integrity for sustainable milling Ti6Al4V under various machining environments, i.e., dry, pure-MQL, LN2, hBN, CuO-doped nanofluids, and hybrid methods. The produced nanofluids' thermophysical and rheological characteristics were examined in the study's initial phase. Because of the results from the first stage, machining performance indicators were assessed in the subsequent milling experiments. As a result, CuO-doped nanofluids gave improved results in terms of viscosity and pH. The best results obtained in the LN2 + CuO hybrid cooling lubrication environment in important machinability outcomes such as tool wear and surface integrity were attributed to the rheological properties of CuO-doped nanofluid and its harmonious cooperation with LN2-cryogenic cooling.

Evaluation of entropy-coupled multi-criteria decision-making methods for enhancing machinability

Optimizing machining parameters is crucial, enhancing machinability while maintaining high product quality standards. This study bridges a critical research gap by evaluating and comparing five Taguchi-based Multi-Criteria Decision Making (MCDM) techniques—Combined Compromised Solution (CoCoSo), Grey Relational Analysis (GRA), Multi-Objective Optimization Ratio Analysis (MOORA), Technique for Order Preference by Similarity to Ideal Solution (TOPSIS), and Complex Proportional Assessment (COPRAS)—coupled with the Entropy method to optimize machining parameters for enhancing machinability in turning medium carbon steel. The focus is on feed rate and cutting speed under dry and Minimum Quantity Lubrication (MQL) environments considering six critical machining responses: material removal rate, surface roughness, main cutting force, cutting temperature, cutting ratio, and tool life.The results reveal that MQL consistently improves machining performance, with COPRAS, TOPSIS, MOORA, and GRA converging on an optimal setting favoring an MQL environment, a 0.14 mm/rev feed rate, and a cutting speed of 137 m/min, whereas CoCoSo suggests a different optimal parameter setting. CoCoSo and GRA demonstrate the highest reliability, evidenced by minimal discrepancies between predicted and experimental results, with absolute percentage errors of 0.647 % and 0.659 %, respectively. The COPRAS method also shows strong predictive accuracy with a 5.573 % error, outperforming MOORA and TOPSIS. Spearman's rank correlation analysis reveals a high agreement between COPRAS, MOORA, and TOPSIS, with COPRAS emerging as a potential replacement for the latter in similar decision-making scenarios. SEM and EDX analyses confirm that MQL conditions reduce tool wear, enhance surface quality, and extend tool life compared to dry machining. This research provides insights into effective parameter optimization strategies for improving machinability and underscores the benefits of adopting MQL for sustainable manufacturing processes.

Effect of phosphide additives on the tribological properties of polyethylsiloxane (PES) in Si3N4 and M50 system

PurposeThe incorporation of phosphide additives is regarded as a highly effective strategy for enhancing the lubricative qualities of base oils. This study aims to assess the lubrication behavior and efficacy of various phosphide additives in polyethylsiloxane (PES) through the employment of the Schwingum Reibung Verschleiss test methodology, across a temperature range from ambient to 300°C.Design/methodology/approachPES demonstrated commendable lubrication capabilities within the Si3N4/M50 system, primarily attributable to the Si-O frictional reaction film at the interface. This film undergoes disintegration as the temperature escalates, leading to heightened wear. Moreover, the phosphide additives were found to ameliorate the issues encountered by PES in the Si3N4/M50 system, characterized by numerous boundary lubrication failure instances. A chemical film comprising P-Fe-O was observed to form at the interface; however, at elevated temperatures, disintegration of some phosphide films precipitated lubrication failures, as evidenced by a precipitous rise in the coefficient of friction.FindingsThe results show that a phosphide reactive film can be formed and a reduction in wear rate is achieved, which is reduced by 64.7% from 2.98 (for pure PES at 300°C) to 1.05 × 10–9 μm3/N m (for triphenyl phosphite at 300°C).Originality/valueThe data derived from this investigation offer critical insights for the selection and deployment of phosphide additives within high-temperature lubrication environments pertinent to PES.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2024-0139/

Prediction and formation mechanism of serrated chips in cutting of SA508–3 steel under enhanced cooling and lubrication environments

The formation of serrated chips is the typical characteristic of high-speed machining. In this paper, a new prediction method based on Williams’ model was presented to give the critical cutting condition for serrated chips formation. The serrated chips formation mechanism under different cooling conditions was analyzed by finite element method. Results indicated that the cutting forces abruptly reduces when the serrated chip forms, the chips serrated degree (Gs) under various cooling conditions (i.e., dry, minimum quantity lubrication (MQL), supercritical CO2 (scCO2), and scCO2-MQL) was described by the following order: scCO2(Gs)＞scCO2-MQL(Gs)＞MQL(Gs)＞dry(Gs). The adiabatic shear owing to the cutting heat and crack initiated from the chip free surface under scCO2 cooling promoted the serrated chips formation.

Experimental investigation into machining performance of magnesium alloy AZ91D under dry, minimum quantity lubrication, and nano minimum quantity lubrication environments

Abstract Due to its low density, magnesium is recognized as a lighter metal and it is favorable for frequent use in industries. It is used in aerospace, biomedical, automotive, and other industrial applications. Magnesium is a promising element that is vital for reducing emissions, improving efficiency, protecting the environment, and enhancing the machine economy. This study analyzes the influence of various cutting environments and parameters on the turning operation of magnesium base alloy (AZ91D). Aluminum 9% and Zinc 1% is the main constituent of AZ91D. The machining process was accomplished using dry, minimum quantity lubrication (MQL), and nano minimum quantity lubrication (NMQL) environments based on their influence on surface roughness (SR) and temperature. Under certain circumstances, it was observed that SR decreases with the increase in the cutting velocity (V c), feed rate, and depth of cut. During cutting of AZ91D in dry conditions, it is preferred to use a moderate speed. Higher temperature was recorded during dry conditions which can significantly reduce the life span of the tool. MQL and NMQL have reduced the cutting temperature by a margin of 25–40% compared to dry machining, thus improving tool life. NMQL has shown decent cooling results compared to other cooling systems.

Effects of machining parameters, ultrasonic vibrations and cooling conditions on cutting forces and tool wear in meso scale ultrasonic vibrations assisted end-milling (UVAEM) of Ti–6Al–4V under dry, flooded, MQL and cryogenic environments – A statistical analysis

Ti–6Al–4V, an alloy of titanium has recently gained focus of research to overcome its machinability challenges. Miniaturization in devices has forced a shift towards micro and meso-scale machining. Sustainability and green manufacturing concepts have shifted focus in machining from cutting fluids towards modern cooling approaches to minimize or eliminate them. In present research, cutting forces & tool wear in Ultrasonic Vibrations Assisted End Milling of Ti–6Al–4V at meso-scale under Dry, Flooded, Minimum Quantity Lubrication & Cryogenic cooling have been analyzed to develop optimum machining parameters. Taguchi L16 orthogonal array was designed to perform experiments keeping Cutting Speed, Feed per tooth, Depth of cut, Ultrasonic vibrations amplitude & Cooling environment as inputs. ANOVA was used to analyze contribution ratios by these parameters towards cutting forces & tool wear. Results indicated that machining conditions, cooling environment and Ultrasonic Vibrations influence cutting forces & tool wear. Depth of cut had the highest influence with 63.41% contribution towards cutting forces while cutting speed remained the highest influencing factor with 39.86% contribution towards tool wear. Cutting forces were reduced by 33.49%, 16.93% and 4.91% while tool wear was reduced by 26.43%, 9.48% and 5.17% under Minimum Quantity Lubrication environment compared to dry, flooded and cryogenic cooling respectively. Cutting forces and tool wear under ultrasonic vibrations were reduced by 24.52% and 13.16% respectively as compared to Conventional Machining (CM). For optimum results, Minimum Quantity Lubrication with low Cutting Speed, Depth of cut, Feed per tooth and high amplitude of ultrasonic vibrations is recommended to machine Ti–6Al–4V.

Fatigue life and transmission efficiency prediction of marine timing gears under 3D mixed lubrication state

The timing gears are the core transmission components of marine diesel engine, whose working conditions are complex and harsh, transient and coupled with the microscopic lubrication state, meshing in the mixed lubrication environment with lubrication-contact coexistence, local asperity contact brings stress concentration, further affects the fatigue life and friction loss. In this study, based on a three-dimensional (3D) line-contact mixed lubrication model, dynamic subsurface stress calculation, fatigue life prediction, and friction loss power study were carried out on timing gears, taking into account transient operating conditions and actual surface roughness. For the established simulation model, an equivalent simulation test of line-contact friction of timing gears was carried out, which can realize the measurement of friction coefficient under the condition of different slip-roll ratios, and make up for the deficiency that the traditional test equipment can only carry out the test under the fixed slip-roll ratio. Although the gear meshing process can only be simulated by the disc specimen due to the limitation of the specimen form, this limitation is similar to the simplified form of the simulation model, which can meet the needs of the verification test. The influence of structure and material on the lubrication state, fatigue life and friction power consumption are studied, which provide theoretical guidance for the tribological optimization design and reliability analysis for the marine timing gears.

Parametric optimization to establish eco-friendly nanofluid minimum quantity lubrication (NMQL) practice for turning superalloy Inconel 718

Purpose The purpose of this paper, an experimental study, is to investigate the optimal machining parameters for turning of nickel-based superalloy Inconel 718 under eco-friendly nanofluid minimum quantity lubrication (NMQL) environment to minimize cutting tool flank wear (Vb) and machined surface roughness (Ra). Design/methodology/approach The central composite rotatable design approach under response surface methodology (RSM) is adopted to prepare a design of experiments plan for conducting turning experiments. Findings The optimum value of input turning parameters: cutting speed (A), feed rate (B) and depth of cut (C) is found as 79.88 m/min, 0.1 mm/rev and 0.2 mm, respectively, with optimal output response parameters: Vb = 138.633 µm and Ra = 0.462 µm at the desirability level of 0.766. Feed rate: B and cutting speed: A2 are the leading model variables affecting Vb, with a percentage contribution rate of 12.06% and 43.69%, respectively, while cutting speed: A and feed rate: B are the significant factors for Ra, having a percentage contribution of 38.25% and 18.03%, respectively. Results of validation experiments confirm that the error between RSM predicted and experimental observed values for Vb and Ra is 3.28% and 3.75%, respectively, which is less than 5%, thus validating that the formed RSM models have a high degree of conformity with the obtained experimental results. Practical implications The outcomes of this research can be used as a reference machining database for various metal cutting industries to establish eco-friendly NMQL practices during the turning of superalloy Inconel 718 to enhance cutting tool performance and machined surface integrity. Originality/value No study has been communicated till now on the turning of Inconel 718 under NMQL conditions using olive oil blended with multi-walled carbon nanotubes-based nanofluid. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-10-2023-0317/

Sustainable machining of superalloy in minimum quantity lubrication environment: leveraging GEP-PSO hybrid optimization algorithm

Sustainable machining of superalloy in minimum quantity lubrication environment: leveraging GEP-PSO hybrid optimization algorithm

Study on the friction drilling behaviors and tribological properties of aluminum matrix composites

This study investigates Al 6063 matrix composites reinforced with different weight percentages of B4C (5%, 10%, 15%, and 20%) produced through powder metallurgy and hot extrusion. The resulting specimens were subjected to a comprehensive investigation to elucidate the effect of B4C reinforcement on the density, tensile strength, transverse rupture strength (TRS), hardness, tribological characteristics, and friction drilling behavior. The pin-on-disk wear tests were conducted in a dry environment, while the friction drilling experiments were performed under constant spindle speed and feed rate conditions, both in dry and minimum quantity lubrication (MQL) environments. The findings revealed a uniform B4C particle dispersion and strong interface bonding in the matrix and that the hardness, tensile strength, TRS, and wear resistance of the specimens increased as the weight fraction of the reinforcement increased. The 15 wt% and 20 wt% B4C composites showed the highest wear resistance, improving by 62.78% compared to Al6063. Higher B4C content reduced specific wear rates and reduced friction coefficients. Among the specimens under investigation, the Al6063 composite reinforced with 15 wt% B4C indicated the highest tensile, transverse rupture, whereas the Al6063 composite with 10 wt% B4C exhibited the best thread-pull-out strength (TPS). The friction-drilled 10 wt% B4C composites showed the highest thread-pull-out strength reaching 373.44 N/mm² in MQL and 329.74 N/mm² in dry conditions.

Influence of Mango Seed Oil on Surface Roughness and Cutting Temperature During Sustainable Turning of AISI 1525 Steel Under Minimum Quantity Lubrication Environment

Mineral oil-based cutting fluids have several mechanical advantages. The use of mineral oil has been questioned due to its adverse effect on machinists and the environment. There is need for a sustainable and biodegradable cutting fluid that can perform the task of problematic mineral oil. This study considered a non-edible vegetable oil, mango oil, as a lubricant in the turning operation of AISI 1525 steel using an MQL mode of fluid application. The performance of mango oil was compared with commercial mineral oil using SR and CT as performance metrics. Experiments were conducted under three levels of SS (355, 500, and 710 rev/min), FR (0.10, 0.15, and 0.20 mm/rev), and DOC (0.75, 1.00, and 1.25 mm). Taguchi L9 orthogonal array was adopted for the experimental settings. Afterward, TOPSIS, a multi-optimization tool was employed to determine the best cutting parameters for machining the workpiece with the tungsten carbide tool. The finding showed that mineral oil outperformed mango oil lubricant in terms of both SR and CT. The optimum CT and SR can be achieved using an SS of 355 rev/min, FR of 0.15 mm/rev, and DOC of 1.00 mm for both mango and mineral oil lubricants.

Investigation of hard milling performance of 60Si2Mn steel under nanofluid minimal quantity lubrication environment

One of the promising solution to improve the hard machining performance is the application of Nanofluid Minimal Quantity Lubrication (NF MQL). The presence of nanoparticles not only improve the cooling lubrication of the based cutting oil but also create more lubricating mechanisms in the cutting zone. This paper aims to study effect of MQL using nano cutting oil on the hard milling process. The Box-Behnken experimental design was utilized to investigate the effects of input variables on the responses. The obtained results indicated that the concentration of nanoparticles, cutting speed and feed rate cause the strong influences on the surface roughness and cutting forces. Also, the appropriate ranges of input variable values can be determined for the required outputs. Moreover, the better cooling and lubricating effects were reported and the machinability of carbide inserts was improved by using Nanofluid Minimal Quantity Lubrication.

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

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

Effects of different factors on the friction and wear mechanical properties of titanium alloy materials with cortical bones at near service conditions.

The artificial joint is one of the most effective methods to treat joint injuries. The service performance of artificial joints is gradually weakened because of the wear of artificial joints in actual service. In order to obtain the potential failure mechanism of the artificial joint in actual service, the study was carried out with the multiple factors that affect the service performance of the artificial joint. The experimental study was carried out on the change rule of mechanical behavior of the contact interface between the artificial joint of titanium alloy and cortical bone. The multi-factor is compression load, contact load, friction velocity, and lubrication environment, respectively. The results indicate that the friction coefficient, wear mass, and wear coefficient of Ti-6A1-4V titanium alloy decreased with the increasing of the compression load. The friction rate and the friction coefficient of Ti-6A1-4V titanium alloy decreased with the increasing of the contact load. The wear mass and friction coefficient of Ti-6A1-4V titanium alloy increased with the increasing of contact load. The lubrication effect is better with the increasing of lubricant concentration. Based on the observation of the SEM, the wear type influenced by compression load and friction rate is mainly abrasive wear and oxidation wear. The wear type influenced by contact load is mainly abrasive wear and adhesive wear. The wear type influenced by lubricants is mainly oxidation wear. When wear mass and wear coefficient are used as the criteria for evaluating friction and wear, the order of influential factors to friction and wear of Ti-6Al-4V titanium alloy plate is friction rate, compression load, contact load, and lubricant concentration. This research can provide a theoretical reference for the optimal manufacture of the artificial joint of titanium alloy and optimal rules of safe service conditions.

Application of machine learning techniques in environmentally benign surface grinding of Inconel 625

This work explores the grinding performance of Inconel 625 by comparing tangential forces and surface roughness under dry, wet, and minimum quantity lubrication (MQL) environments. Response surface methodology (RSM) and machine learning (ML) techniques establish correlations between inputs and outputs. RSM shows the quadratic regression model effectively captures experimental variability. Four ML models, namely: multilayer perceptron, KNN, and SVM with two kernels, were implemented to predict outcomes, among which KNN appeared as a better-suited model. Lower tangential forces and better ground surface quality support the suitability of MQL grinding compared with dry and wet grinding. Micro-graph investigations of the ground surfaces and chip morphology findings also upkeep the emergence of MQL grinding as a sustainable alternative for Inconel 625 grinding.

Friction behavior of polycrystalline diamond compact and the evolution of the friction film under different matching materials

The friction and wear behavior of polycrystalline diamond compact (PDC) and the evolution of the friction film under nano‑molybdenum disulfide (MoS2) lubricating additives after leaching cobalt were investigated under different friction pairs (SiC, ZrO2, and Al2O3). The results showed that the friction coefficient and wear rate of different matching materials and PDC after leaching cobalt in a solid–liquid lubrication environment are related to the amount of friction film formed on the sliding interface, the evolution behavior, and the filling effect of lubricating additives on the friction interface. Different matching materials and PDC after leaching cobalt will undergo dissimilar chemical reactions during the sliding process, and different wear mechanisms are obtained.

A sustained release lubrication method of agarose-sodium hyaluronate hydrogels for artificial joint.

The artificial joint prosthesis's surface is subjected to wear due to the destruction of the joint lubrication environment after surgery. In this study, an agarose-sodium hyaluronate hydrogel was used as lubricant additive in order to supply and preserve the lubricating fluid of artificial joint prostheses. A ball on disc experiment was conducted using this hydrogel to evaluate the lubrication efficiency and release rate under various frequencies. The results showed that this hydrogel could release lubricant under pressure and then absorb the released fluid after decompression. Furthermore, the agarose-sodium hyaluronate hydrogel acted as an effective transport mechanism to release sodium hyaluronate lubricant into the metal-on-polymer friction interface. Compared with pure water lubrication, the friction coefficient and wear volume were reduced by up to 62.9%, and 86.9% respectively. Moreover, the proposed lubrication method provided a long-term lubrication on artificial hip joints.

A new TiAlSiN coated tool and its machining performance evaluation for milling difficult-to-machining materials under MQL conditions

In this study, the Si and Al contents in a coating composition were improved, and a new TiAlSiN-coated tool was fabricated using high-power pulsed magnetron sputtering (HiPIMS). For comparison purposes, four types of coated tools, typically used in the market, were selected to mill 304 stainless steel in a minimum quantity lubrication environment. To evaluate the machining performance of the tools, the criteria of tool wear, workpiece surface roughness, and milling force were considered. The machining performance of the TiAlSiN-coated tools remained stable for all four working conditions, and it had the smallest compound milling force and tool wear in the experiment. The primary wear forms of the tools were coating peeling, oxidation wear, and adhesive wear. Under working conditions 1 and 2, due to the lower initial surface friction coefficient and thermal barrier effect, the workpiece surface roughness of the TiN-coated tools was the smallest, followed by that of the TiAlSiN. However, under inadequate working conditions, because of the good wear resistance of the TiAlSiN coating, it was not rapidly worn. This resulted in a lower average friction coefficient during processing and the workpiece surface exhibited the minimum surface roughness. A comparative analysis of the processing state of the five coatings under four groups of parameters indicated that the TiAlSiN coating had good processing stability, wear resistance, and a low surface friction value. The TiAlSiN-coated tools had better machining performance than the other four commercial-coated tools for 304 stainless steel machining, especially under working conditions 3 and 4.