Minimum Quantity Lubrication Milling Research Articles

A review on minimum quantity lubrication (MQL) assisted machining processes using mono and hybrid nanofluids

PurposeBecause many cutting fluids contain hazardous chemical constituents, industries and researchers are looking for alternative methods to reduce the consumption of cutting fluids in machining operations due to growing awareness of ecological and health issues, government strict environmental regulations and economic pressures. Therefore, the purpose of this study is to raise awareness of the minimum quantity lubrication (MQL) technique as a potential substitute for environmental restricted wet (flooded) machining situations.Design/methodology/approachThe methodology adopted for conducting a review in this study includes four sections: establishment of MQL technique and review of MQL machining performance comparison with dry and wet (flooded) environments; analysis of the past literature to examine MQL turning performance under mono nanofluids (M-NF); MQL turning performance evaluation under hybrid nanofluids (H-NF); and MQL milling, drilling and grinding performance assessment under M-NF and H-NF.FindingsFrom the extensive review, it has been found that MQL results in lower cutting zone temperature, reduction in cutting forces, enhanced tool life and better machined surface quality compared to dry and wet cutting conditions. Also, MQL under H-NF discloses notably improved tribo-performance due to the synergistic effect caused by the physical encapsulation of spherical nanoparticles between the nanosheets of lamellar structured nanoparticles when compared with M-NF. The findings of this study recommend that MQL with nanofluids can replace dry and flood lubrication conditions for superior machining performance.Practical implicationsMachining under the MQL regime provides a dry, clean, healthy and pollution-free working area, thereby resulting the machining of materials green and environmentally friendly.Originality/valueThis paper describes the suitability of MQL for different machining operations using M-NF and H-NF.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2023-0131/

Experimental investigation of oxygen as carrier gas in minimum quantity lubrication milling of H11 die steel

Minimum quantity lubrication (MQL) is one of the promising green manufacturing technologies to meet the challenges in the dry machining of hardened die steels. The present work aims to show the effects of various machining environments like dry, MQL with compressed air and MQL with oxygen in the milling of H11 die steel. A biodegradable ester LRT 30 (24cSt at 40 °C) was used as a cutting fluid. The results showed that the MQL with an oxygen-enriched environment provided better results in terms of reduction in cutting force, surface roughness and tool wear. It was also found that the MQL with oxygen was more effective when the cutting velocity ranges between 125 and 150 m/min, as compared with conventional MQL with compressed air. The oxygen enriched MQL helps in retaining the tool's sharpness for a longer period due to the formation of hard oxide layer formation on the tool. The cutting tool under MQL with an oxygen environment removes 40% more material when compared to the conventional MQL with air for the same average flank wear width of 0.3 mm.

Tribological Performance of Different Concentrations of Al2O3 Nanofluids on Minimum Quantity Lubrication Milling

Nanofluid minimum quantity lubrication (NMQL) is a green processing technology. Cottonseed oil is suitable as base oil because of excellent lubrication performance, low freezing temperature, and high yield. Al2O3 nanoparticles improve not only the heat transfer capacity but also the lubrication performance. The physical and chemical properties of nanofluid change when Al2O3 nanoparticles are added. However, the effects of the concentration of nanofluid on lubrication performance remain unknown. Furthermore, the mechanisms of interaction between Al2O3 nanoparticles and cottonseed oil are unclear. In this research, nanofluid is prepared by adding different mass concentrations of Al2O3 nanoparticles (0, 0.2%, 0.5%, 1%, 1.5%, and 2% wt) to cottonseed oil during minimum quantity lubrication (MQL) milling 45 steel. The tribological properties of nanofluid with different concentrations at the tool/workpiece interface are studied through macro-evaluation parameters (milling force, specific energy) and micro-evaluation parameters (surface roughness, micro morphology, contact angle). The result show that the specific energy is at the minimum (114 J/mm3), and the roughness value is the lowest (1.63 μm) when the concentration is 0.5 wt%. The surfaces of the chip and workpiece are the smoothest, and the contact angle is the lowest, indicating that the tribological properties are the best under 0.5 wt%. This research investigates the intercoupling mechanisms of Al2O3 nanoparticles and cottonseed base oil, and acquires the optimal Al2O3 nanofluid concentration to receive satisfactory tribological properties.

An experimental study on cutting temperature and burr in milling of ferritic stainless steel under MQL using nano graphene reinforced cutting fluid

In this experimental study, cutting temperatures and burr forms were investigated during MQL (Minimum Quantity Lubrication) milling of AISI 430 ferritic stainless steel. In the experiments, uncoated and TiN (Titanium Nitride) coated WC (Tungsten Carbide) cutting tools were used and the experiments were performed under dry and MQL conditions. A commercial vegetable cutting fluid was chosen as cutting fluid and MQL flow rates were applied at 20 ml/h and 40 ml/h. Additionally, a nanofluid was prepared by adding nano graphene particles to the vegetable cutting fluid at 0,5%wt. Depending on the experimental results, low cutting temperature and small burr forms could have been obtained in the results of using TiN coated WC cutting tool and applying MQL method. In addition, the minimum cutting temperature and burr form were observed during MQL milling with nanofluid. Copyright © 2017 VBRI Press.

The Effects of MQL and Dry Environments on Tool Wear, Cutting Temperature, and Power Consumption during End Milling of AISI 1040 Steel

Minimum quantity lubrication (MQL) is a sustainable method that has been efficiently applied to achieve machinability improvements with various materials in recent years, such as hardened steels, superalloys, soft metals, and composites. This study is the first to focus on the performance evaluation of MQL and dry milling environments with AISI 1040 steel. The tool wear, cutting temperature, and power consumption were considered as the quality responses while cutting speed, feed rate and machining environment are taken as input parameters. The effects of the influential factors are analyzed using analysis of variance (ANOVA) and bar charts. Additionally, Taguchi signal-to-noise (S/N) ratios are utilized in order to determine the optimum parameters for the best quality responses. The results show that the MQL system provides better performance compared to dry milling by reducing the tool wear, cutting temperature, and power consumption. According to the ANOVA results, the cutting environment affects the cutting temperature (37%) and power consumption (94%), while cutting speed has importance effects on the tool wear (74%). A lower cutting speed (100 m/min) and feed rate (0.10 mm/rev) should be selected under MQL conditions to ensure minimum tool wear and power consumption; however, a higher feed rate (0.15 mm/rev) needs to be selected along with a low cutting speed and MQL conditions to ensure better temperatures. A comparative evaluation is carried out on the tool wear, cutting temperature, and power consumption under MQL and dry environments. This investigation is expected to contribute to the current literature, highlighting the superiority of sustainable methods in the milling of industrially important materials.

Development of a cyclic liquid nitrogen injection system and its application to minimum quantity lubrication milling of the Ti-6Al-4V alloy

Development of a cyclic liquid nitrogen injection system and its application to minimum quantity lubrication milling of the Ti-6Al-4V alloy

Evaluating the effects of nano-fluids based MQL milling of IN718 associated to sustainable productions

The aeronautical industry is constantly striving for goals related to lesser production/maintenance time and cost. In this regard, aero-engines made up of Nickel-based alloy are preferred for high performance to improve the burning efficiency. However, the processing of the Nickel-based alloys remain challenging in manufacturing industry with the aim of sustainable production. This research investigated the manufacturing progress of face milling of Inconel 718 by using two different lubrication conditions; minimum quantity lubrication (MQL) and nanofluids based minimum quantity lubrication (NF-MQL). A high degree of sustainability was achieved through increasing productivity (material removal rate) and quality (surface roughness) enhancement while minimizing the power and temperature. The impacts of four most influencing parameters including feed rate, speed, flow rate and depth of cut were investigated on sustainable production performance measures. Empirical models of surface roughness, temperature, material removal rate and power were developed using response surface methodology. Analysis of the developed empirical models and validation were executed through analysis of variance and confirmatory experiments results. Finally, a multi objective optimization was implemented to attain maximum sustainability effect by generating a compromise between lowest surface roughness and cost, and highest material removal rate. The results revealed that the depth of cut is the most significant process parameter for both lubrication environments. The results show the NF-MQL as the better alternative which resulted in 20.1%, 14.7% and 13.3% percentage reduction for surface roughness, temperature and power, respectively. Furthermore, the results revealed that NF-MQL resulted in better desirability achievement (71.3%) as compared to MQL (70.1%).

Effects of Physicochemical Properties of Different Base Oils on Friction Coefficient and Surface Roughness in MQL Milling AISI 1045

Minimum quantity lubrication (MQL) is an emerging green and resource-saving machining technique jetting minute amount lubricants and gas after mixing and atomization. However, MQL development is restricted to mineral oils because of its undegradability and threat to the environment and human health. Vegetable oils can replace mineral oils as base oil for MQL benefitting from its biodegradability and renewable property. Nevertheless, the lubrication mechanism at the tool-workpiece interface of different vegetable oils with various physicochemical properties has not been revealed systematically. In order to verify the interfacial lubrication characteristics of different vegetable oils, MQL milling experiments of AISI 1045 based on five vegetable oils (cottonseed, palm, castor, soybean, and peanut oils) were carried out. The experimental results showed that, palm oil obtained the lowest milling force (Fx = 312 N, Fy = 156 N), friction coefficient (0.78), and surface roughness values (Ra = 0.431 μm, RSm = 0.252 mm) and the smoothest surface of workpiece. Furthermore, the physiochemical properties (composition, molecular structure, viscosity, surface tension, and contact angle) of vegetable oil were analyzed. Palm oil with high content of saturated fatty acid, high viscosity and small contact angle can form the lubricating oil film with the highest strength and the largest spreading area at the tool-workpiece interface. Therefore, palm oil can achieve the optimal lubrication effect.

Study of oil flow rates effects on lubricant oil behaviour during minimum quantity lubrication milling process

Minimum quantity lubrication (MQL) technology has been utilized extensively on these days as an alternative method to conventional cooling technique. A study to understand the know-how of tiny lubricant oil mists to effectively penetrate the cutting zone is important. However, such study is still scarce since the setup of the experimental probe during the machining process is on-going is difficult. The objective of this study is to analyse the lubricant oil film behaviour accumulated on AL6061 workpiece during MQL milling process by using a non-intrusive technique called as laser-induced fluorescence (LIF) method. The experiment was conducted under different oil flow rates to measure the thickness fluctuation of the lubricant oil film. Moreover, the surface roughness of workpiece after the milling process was also measured. As a result, the lubricant oil thickness was found to fluctuate in between 0.2 mm and 0.4 mm for two lower oil flow rates due to the tendency of evaporation. At higher oil flow rate, the lubricant oil fluctuated at higher thickness, i.e. 0.4 mm and 0.5 mm. On the other hand, the obtained mean surface roughness values did not reveal any remarkable difference from each other. However, lower mean surface roughness values were detected at 90 mm distance from machining starting point due to the accumulation of lubricant oil towards the end of workpiece. Therefore, the results of the oil behavior were successfully confirmed and thus MQL milling performance under different oil flow rates condition was clarified.

Investigations on the effect of nozzle angle and air flow rate during nanofluid Minimum Quantity Lubrication milling of Aerospace alloy Al7075-T6

Present day industries are focusing upon finding various methods and techniques to implement sustainable manufacturing, which is ‘the need of the hour’. With increase in global competition, industries are striving hard to reduce the machining costs, which is a major contributor for ‘manufacturing cost per part’, in an industry. Conventional method of using large quantity of coolant/cutting fluids in several liters per hour, to cool machining zone is causing enormous concern. Strict Government regulations are necessitating industries to replace flood-coolant assisted machining by new techniques like ‘Minimum Quantity lubrication’ (MQL) coolant supply technique. The present work deals with investigating the effect of varying nozzle angle and air-flow rate during MQL assisted surface milling of aerospace aluminum Al7075-T6 alloy, using uncoated carbide tool. Three methods of coolant supply namely Dry, MQL and nanofluid MQL (nano particles us pended oil with MQL) are experimented. Cutting speed [150m/min, 208m/min, 264 m/min], feed rate [95 mm/min, 110 mm/min, 125 mm/min] and depth of cut [0.5 mm, 1.3 mm, 2 mm] are chosen as process variables. Two nozzle angles 25°C and 500, with 1.5 kg/cm2 and 3 kg/cm2 air flow rates were investigated. Best results were obtained for air flow rate of 1.5kg/cm2. Optimumnozzleangle was found to be 25°C. To obtain lowest temperature and reduced heat generation, nanofluid MQL machining is a feasible option. With regards to MQL technique, for obtaining better surface finish with reduced surface roughness of the work piece (Al7075-T6), nanofluid MQL technique is best.

Physicochemical properties of degradable vegetable-based oils on minimum quantity lubrication milling

With increasing attention being paid to environmental and health problems in metal machining, developing an environmentally friendly cutting fluid is an urgent need. Degradable vegetable oils with non-toxicity and renewability are becoming increasingly popular. However, the mechanism of physicochemical properties of different vegetable oils is not clear on minimum quantity lubrication (MQL) milling. In the study, five typical vegetable oils (i.e., cottonseed, palm, castor, soybean, and peanut) were selected as base oil to experimentally evaluate the lubrication performance of the tool–workpiece interface compared with synthetic cutting fluid. With Grade 45 steel as workpiece material, the lubrication performance was evaluated in terms of milling force, surface roughness and surface morphology, as well as the composition, molecular structure, and viscosity of vegetable oils. Results showed that the vegetable-based oils achieved lower milling force and better surface quality than the synthetic cutting fluid. Among them, palm oil obtained the lowest milling force (Fx = 309 N, Fy = 154 N) at 7.76% and 13.6% lower than that of synthetic cutting fluids. The surface quality obtained by vegetable-based oils is superior to that of the synthetic cutting fluid, and the cottonseed and palm MQL acquired the best surface, while soybean obtained the worst surface. Furthermore, the results of surface roughness are consistent with those of surface morphology. Finally, according to the analysis of composition and molecular structure, palm and cottonseed with high content of saturated fatty acids are more suitable as MQL base oils.

Effect of MWCNT on surface roughness and burr height in MQL milling of AISI 430 ferritic stainless steel

Stainless steel materials have been used in many fields such as automotive, aviation, medical industries, etc. In addition, these materials are classified as difficult-to-cut materials due to low thermal conductivity and work-hardening tendency. Therefore, studies on machining of these materials have been performed in order to understand the basic of the process. In this study, surface roughness and burr height were investigated in MQL (Minimum Quantity Lubrication) milling of AISI 430 ferritic stainless steel. In MQL milling, commercial vegetable cutting fluid and MWCNT (Multi Walled Carbon Nanotube) reinforced vegetable cutting fluid were used. The milling experiments were also conducted under dry condition. In the experiments, uncoated WC (Tungsten Carbide) and TiN (Titanium Nitride) coated WC cutting inserts were used. Based on the experimental results, MQL method reduced the surface roughness and burr heights and better surfaces were obtained by using nanofluids in MQL method.

Investigations on effect of nanofluid based minimum quantity lubrication technique for surface milling of Al7075-T6 aerospace alloy

Machining is one of the largest and significant manufacturing processes. Due to strict environment regulations and water scarcity, reduction in the usage of coolants/cutting fluids has been the need of the hour. The present work focuses upon Analysis of Variance (ANOVA) based investigations using full factorial design on the effect of Minimum Quantity Lubrication (MQL) coolant supply instead of conventional flood coolant method, for surface milling of aerospace Al7075-T6 Aluminum slabs using uncoated carbide tool. Parameters chosen were spindle speed, feed rate and depth of cut with spindle speed in terms of rpm (3000, 4000, 5000, 6000, 7000), feed rate in mm/min (95, 105, 110, 115, 125) and depth of cut in mm (0.5, 1.0, 1.3, 1.6, 2.0). Out of 3 methods of coolant supply, MQL technique yielded superior results compared to dry milling and nanofluid MQL milling, in terms of surface finish (Ra) and minimum temperature values (T) that were observed for nanofluid MQL coolant supply technique. Addition of nanoparticles to the coolant has provided good effect in reducing the temperature at the work tool interface, without affecting the milling performance characteristics.

Nanofluid-based Minimum Quantity Lubrication (MQL) Face Milling of Inconel 625

Machining with minimum quantity lubrication (MQL) has gained widespread attention to boost machining performance of difficult to machine materials such as Ni-Cr alloys, especially to reduce the negative impact of conventional flooded machining on environment and machine operator health. The present study is aimed to evaluate MQL face milling performance of Inconel 625 using nano cutting fluid based on vegetable oil mixed with multi-walled carbon nanotubes (MWCNT). Experiments were designed with 2-level factorial design methodology. ANOVA test and desirability optimisation method were employed to arrive at optimised milling parameters to achieve minimum tool wear and machined surface quality. Experiments were performed under nanoparticles based minimum quantity lubrication (NMQL) conditions using different weight concentrations of MWCNT in base oil: 0.50, 0.75, 1, 1.25 and 1.5 wt. %; and pure MQL environment (without nanoparticles). The optimal MQL milling parameters found are cutting speed: 47 m/min, table feed rate: 0.05 mm/tooth and depth of cut: 0.20 mm. The results revealed improvement in the surface finish (Ra) by 17.33% and reduction in tool flank wear (VB) by 11.48 % under NMQL face milling of Inconel 625 with 1% weight concentration of MWCNT in base oil compared to pure MQL machining conditions.

Selection of an ideal MQL-assisted milling condition: an NSGA-II-coupled TOPSIS approach for improving machinability of Inconel 690

Through minimum quantity lubrication (MQL) technology, small droplets of cutting fluid accompanied by compressed air are sprayed into the tool-workpiece interface. Hence, it offers effective lubrication/cooling and advances machining performance without using the significant amount of cutting fluids. Conversely, due to the biodegradable and non-pollutant properties of vegetable oils, these are widely employed as a base fluid in MQL technology. Considering the benefits of MQL-vegetable oil synergy, this paper aims to determine the best possible sequence of MQL milling parameters of Inconel 690 using castor oil as a lubricant. Here, response surface methodology (RSM) has been exploited to make a correlation between input and machining responses. To deal with the optimization problem, a two-stage computational approach was adopted. The first theory was non-dominated sorting genetic algorithm-II (NSGA-II) and the second method was technique for order preference by similarity to ideal solution (TOPSIS). NSGA-II has been exploited to explore for the candidate solution, and TOPSIS has been deployed to find out the best compromise solution. Finally, this manuscript compares the outcomes of the adopted approach with experimental outcomes to determine the efficacy of the proposed model. It was revealed from the comparison that the average error obtained between the predicted and the experimental response is less than 1%.

Research on surface integrity in graphene nanofluid MQL milling of TC21 alloy

As a new type of damage-tolerance titanium alloy, TC21 alloy is widely used in aerospace. However, TC21 is a difficult-to-machine material owing to its low thermal conductivity, high chemical activity and low elasticity modulus. In this work, minimum quantity lubrication (MQL) with graphene nanofluid was adopted in TC21 milling. In order to evaluate the effects of graphene nanoparticle on the surface integrity, a series of milling experiments were performed under the dry, gas, pure MQL and graphene nanofluid MQL condition respectively. Results showed that the graphene additive was effective for improving the surface integrity. Overall, the results could be explained that graphene additive could enhance the cooling and lubrication performances of the oil film formed in cutting zone. The findings of this work are expected to give a feasibility and some experimental basis for the application of the graphene additive in MQL milling.

Research on surface integrity in graphene nanofluid MQL milling of TC21 alloy

As a new type of damage-tolerance titanium alloy, TC21 alloy is widely used in aerospace. However, TC21 is a difficult-to-machine material owing to its low thermal conductivity, high chemical activity and low elasticity modulus. In this work, minimum quantity lubrication (MQL) with graphene nanofluid was adopted in TC21 milling. In order to evaluate the effects of graphene nanoparticle on the surface integrity, a series of milling experiments were performed under the dry, gas, pure MQL and graphene nanofluid MQL condition respectively. Results showed that the graphene additive was effective for improving the surface integrity. Overall, the results could be explained that graphene additive could enhance the cooling and lubrication performances of the oil film formed in cutting zone. The findings of this work are expected to give a feasibility and some experimental basis for the application of the graphene additive in MQL milling.

Parameter optimization during minimum quantity lubrication milling of TC4 alloy with graphene-dispersed vegetable-oil-based cutting fluid

Minimum Quantity Lubrication has been widely used in the titanium alloy milling process as an advanced and clean means of cooling and lubrication. The Minimum Quantity Lubrication parameters have a significant influence on the milling characteristics and so, determining an optimal Minimum Quantity Lubrication parameter combination is vital to obtaining the best milling characteristics. In this study, Minimum Quantity Lubrication with graphene-dispersed vegetable-oil-based cutting fluids was adopted in the milling of TC4 alloy, where the cutting fluids were prepared by dispersing graphene nanoparticles into the vegetable-oil-based cutting fluid to improve the milling characteristics of the TC4 alloy. The integrated Taguchi-Principal component analysis-Gray relational analysis optimization method was used to evaluate the effects of the Minimum Quantity Lubrication parameters on the milling characteristics and obtain the optimal Minimum Quantity Lubrication parameter combination. The milling characteristics of TC4 alloy, namely, the milling force, milling temperature, surface micro-hardness, and surface roughness were evaluated and analyzed, and the optimal Minimum Quantity Lubrication parameter combination was obtained. A verification experiment was conducted and the results indicated that all the four milling characteristics were significantly improved after the optimization process. The improvement rates of the milling force, milling temperature, surface micro-hardness, and surface roughness are 18.13%, 13.59%, 8.36%, and 24.82%, respectively. In summary, appropriately chosen Minimum Quantity Lubrication parameters can enhance the lubrication and cooling properties of the oil film and improve the milling characteristics. The results of this study attest to the feasibility of the integrated Taguchi-Principal component analysis-Gray relational analysis optimization method and provide an experimental basis for the application of graphene additive in Minimum Quantity Lubrication milling.

Numerical and experimental optimizations of nozzle distance in minimum quantity lubrication (MQL) milling process

Minimum quantity lubrication (MQL) is the efficient and environmentally friendly technology, which is desirable to achieve sustainability during machining process. The nozzle distance has its significance in dominating the MQL spray and the related droplet transportation and penetration. In this paper, the nozzle distance has been optimized for MQL milling process through numerical and experimental methods. A two-way computational method has been employed to solve for the comprehensive flow field and particle trajectories, with the wall condition established on the spray impingement theory. The interactions of air flow rates and spindle rotational speeds on droplet penetration are investigated in details. The optimal ranges of nozzle distance setup obtained by simulation for different conditions were verified via slot milling tests, in which the nozzle distances were selected according to the key points obtained in the numerical process. The cutting force and surface roughness were recorded for the verification of adhesion ability and the related cutting performance. The comparison between numerical simulations and milling experiments has shown great consistency. This paper has achieved better understanding of the nozzle orientation setup and device development in MQL milling process, especially for external MQL. The theoretical basis and scientific instruction have been provided for the optimization of MQL operating parameters in industrial applications.

MQL milling of TC4 alloy by dispersing graphene into vegetable oil-based cutting fluid

Titanium alloy TC4 is widely used in aerospace, petrochemical, shipbuilding, automobile, and medicine due to its excellent comprehensive performances. However, TC4 is a difficult-to-machine material because of its low thermal conductivity, large friction coefficient, high chemical activity, and low elasticity modulus. In this paper, Minimum Quantity Lubrication (MQL) with vegetable oil-based cutting fluid was adopted in TC4 milling. Meanwhile, graphene nanoparticles were dispersed into the vegetable oil-based cutting fluid to improve the cooling and lubrication performances. In order to evaluate the performances, a series of milling experiments were conducted under the four cooling/lubrication conditions (dry, gas, pure MQL, and graphene MQL). The milling characteristics of TC4 in terms of milling force, milling temperature, tool wear, and surface integrity were compared. Results showed that the graphene additive was effective for improving the milling characteristics. Overall, the results could be explained that the graphene additive could enhance the cooling and lubrication performances of the oil film formed in the milling zone. The findings of this paper are expected to be meaningful to provide some experimental basis for the application of the graphene additive in MQL milling.