Sustainable machining using eco-friendly cutting fluids: a review

contain some vegetable oil. Due to their eco-friendly, thermal, and tribological qualities, these types of machining fluids are becoming increasingly popular among researchers throughout the world. The authors summarized published research studies on the use of eco-friendly machining fluids (including nanofluids) in various metal removal processes such as turning, milling, grinding, and drilling in this review paper. The impact of several biodegradable oil-based machining fluids on performance metrics such as surface irregularity, machining force, tool wear, power demand


Introduction
Sustainability in the machining process is generally achieved by preserving the social, economic, environmental, and technological dimensions for a longer period of time.Sustainability is a new paradigm in manufacturing because of the fact that organizations face diverse challenges.erefore, sustainability in manufacturing is the ability of the organization to ful ll the required demands without compromising the environment and destroying natural resources.
Eco-friendly cutting uids are nontoxic, environmentally friendly cutting uids that are free of chemicals such as ammonium borohydride (amines), chlorine, and sulphur.It has superior properties in terms of corrosion resistance, e ective lubrication, and reduced mist and sludge formation.
Drivers of conventional manufacturing include cost, time, and quality whereas, modern manufacturing includes environmental-driven objectives in addition to cost, time, and quality.Major drivers of sustainability are market, technology, societal, and regulatory drivers as presented in Figure 1.
Environment-driven objectives are attributed to low carbon emissions, minimizing utilization of natural resources and energy resources.
ese environment-driven objectives are added to the manufacturing system to minimize pollution and raw material usage, reduce energy intensity, and recycle or reuse waste.ese attributes are put together to move towards sustainable manufacturing.
Sustainable machining can be de ned as a machining process that can be sustained for a longer duration of time with the same e ciency.It reduces waste and minimizes its environmental impact by conserving natural resources and energy.It is also known as a "green manufacturing process."Sustainable or green manufacturing can be approached in terms of energy reduction, water reduction, emission reduction, the optimal supply pressure of the cutting uids (at a pressure of 5.5 bar), cost minimization, safety maximization, and waste product reduction during a particular manufacturing practice [1][2][3][4].Figure 2 demonstrates different elements of the sustainable manufacturing processes.
e reduction of all these parameters should be implemented at the source for better e ectiveness.
Sustainable machining can be achieved by many approaches and techniques such as dry cutting, minimum quantity lubrication (MQL), use of vegetable oil-based cutting uids, high-pressure coolants, cryogenic cooling, and hybrid cooling techniques as presented in Figure 3.
Use of biodegradable cutting uids in the machining is the approach for sustainable machining in a particular manufacturing organization.Application of biodegradable or eco-friendly cutting uids leads to no release of harmful gases during the machining, and is harmless to the operator's skin.Machine operator health is a big concern due to performing machining operations in the close vicinity of the machining zone which results in inhaling harmful gases released by the mineral-based cutting uids.erefore, many approaches have been implemented for the safe use of eco-friendly cutting uids.
Manufacturing environments face many challenges such as economic, social, environmental, and technological.Economic challenges comprise a shorter product life cycle, demand uctuation, and product variety.Environment challenges mean climate change and the depletion of natural resources.It is another aspect that is enforced in manufacturing.Societal challenges include an aging workforce and the nonavailability of skilled manpower.Whereas, technological challenges attribute obsolesce to the technology used in a particular manufacturing organization.
ese di erent challenges put together result in di erent types of stresses, requirements, or needs in the manufacturing organization and these challenges in some sense force the organization to be more focused on sustainable development, where they would be looking at how to conserve the existing natural resources.erefore, from this literature it can be concluded that manufacturing organizations face a wide range of sustainability-related challenges, necessitating the adoption of a new paradigm.In addition to cost, time, and quality,

Machining Fluids
e main objective of the application of machining uids in di erent manufacturing processes is to remove the heat generated and to decrease the friction between the tool and workpiece [5,6].When the cutting uid is sprayed into the clearance face, it cools more e ectively, especially when the pressure is at least 300 kPa.Reduction in the heat produced in the metal removal processes will result in longer tools.
e workpiece and tool have a longer life expectancy and are less distorted.In machining uids, coolant and lubricant properties should be present [7].Cooling properties of cutting uids remove the heat created, while lubricating properties minimize friction between the tool and the workpiece.Performance, conditions, and maintainability are among the most important factors to consider while selecting a machining uid [8].Table 1 contains the information on these characteristics.

Preparation of Nano-Cutting
Fluids.Preparation of ecofriendly cutting uids requires base uids, vegetable-based oil, surfactant, emulsi er, and additives.Generally, distilled water is used as the base uid due to its highest speci c heat capacity.Recently, some of the commonly used vegetable oils used for cutting uids preparation include canola oil, cotton seed oil, ground nut oil, coconut oil, and sun ower oil [9].e common types of surfactants used for cutting uid are fatty acid, ester, alcohol, sorbitan, and phenol ethoxylate.An emulsi er is the most important component for the reparation of the cutting uids.After blending with the base uids, it ensures good lubricity, solubility, better thermal stability, and low foaming tendency.Commonly used emulsi ers include various fatty acid esters and ethers.
Preparation of the vegetable oil-based cutting uids starts with taking the required quantity of the base uids, followed by mixing virgin vegetable oil in the required proportion with the base uids.e emulsi er is added to this solution for proper mixing of the solute and solvent.Add the nanoparticles to the cutting uid which enhances the properties of cutting uids like thermal conductivity.
e selected surfactant is added to the already prepared solution to lower the surface tension between the two liquids.At last, magnetic stirrer is used for the proper mixing of particles in the solution.e owchart for the preparation of the vegetable oil-based cutting uids is present in Figure 4.

Testing and Characterization of Nano-Cutting Fluids.
Testing and characterization of the cutting uids include measurement of viscosity characteristics, activation energy, thermal gravimetric analysis, thermal conductivity, speci c heat, bio-degradability test, corrosion test, wettability study, pH, density, ash point, and re point of the cutting uids.
From these articles, it can be concluded that machining uids reduce heat generated during operation by decreasing friction between tool and workpiece.e most important factors to consider are performance, conditions, and maintainability.For cutting uid preparation, the emulsi er is one of the most critical components.Cutting uids should possess a low foaming tendency, better thermal stability, and

Application of Vegetable Oil-Based Cutting Fluids in Machining
Vegetable oil-based machining fluids are the cutting fluids that are prepared from plant oils, water, and air, or other raw ingredients [10,11].Biodegradable machining fluid is used for cooling and lubrication mechanisms, particularly for metal removal processes.e main aim of the utilization of these fluids is to decrease harmful gases released during machining operations and to increase biodegradability [12][13][14].In addition, these machining fluids keep the works and tools at a stable temperature, increase tool life, and prevent rust formation.Eco-friendly cutting fluids are highly biodegradable and have no adverse environmental impact [15,16].Some of the common vegetable-based cutting oils are cottonseed, groundnut, coconut, sesame, canola, and soybean [17][18][19][20][21]. Table 2 lists the physical characteristics of cottonseed and groundnut oil.
3.1.Turning.Sustainability and energy analysis during dry turning operations were investigated [22].e author has reported that the exergy loss reduces with an increase in the machining speed until it attains the least value.e optimal values of machining conditions were achieved with minimum energy consumption and exergy loss.However, the author [23] presented optimal machining conditions to minimize the power required in the metal removal process.It is found that the cutting tool has to be carefully chosen based on the power required and the cutting velocity of the tool and the properties of the tool material so that the energy consumption can be reduced.
Researcher [24] performed a machining operation in the turning of Haynes 25 super alloy and concluded how to decrease the amount of lubrication used in machining with good surface roughness and good machining capability at higher cutting speeds.Selection of appropriate machining fluids to diminish the influence of heat released during machining for better tool life, less surface irregularity, and improved accuracy is an important aspect in traditional machining processes [25,26].In addition, the author has presented that the metal removal rate is more at higher values of the machining parameters.Whereas, the effects of the cutting fluids on the environment and operators' health are presented [27].In this article, a model for the preparation of cutting fluids and their behavior along with how to decrease the flow of machining fluids during different cutting operations is discussed.
Vegetable oil-based metal working fluids have been used to study performance in terms of cutting force, work piece surface polish, tool wear, and cutting zone temperature in the machining of various materials [28]. is article summarizes that eco-friendly cutting fluids have similar performance as metal working fluids.e use of different percentages of additives mixed with cutting fluids and dry cutting fluids was investigated.It is observed that the performance of canola oil-based machining fluid was superior to that of refined sunflower oil while turning AISI 304L [29].
e use of coconut oil-based machining fluid while turning SS304 reported and estimated both the tool wear and surface irregularity.e comparison was made by using the coconut oil-based machining fluid as an emulsion and also as a neat machining oil.ey observed that emulsion gives better results than straight cutting oil by reducing tool wear and increasing surface smoothness.e coconut oil-based machining fluid also outperformed the neat cutting oil and conventional soluble oil in terms of reduction of machining force and temperature [30].
Eco-friendly cutting fluid is prepared using jatropha oil and modified in its chemical structure by the transesterification process using various concentrations of jatropha methyl esters [31].e basic fluid properties were tested in terms of viscosity, density, and lubrication properties.ese fluids were used during turning different steels and their performances were compared with synthetic fluids.ey also found that modified oil reduces the cutting forces and temperature to a great extent.Whereas, researcher [32] performed investigation on jatropha and Pongamia oil machining fluids in the turning of AA 6061. is investigation reported that Pongamia oil-based machining fluid can be used for a better surface finish at lower cutting speeds, whereas jatropha oil-based cutting fluids at high speeds.
Different sustainable machining fluids were prepared using oils such as coconut, sunflower, rapeseed, palm oil, and high Erucic rapeseed.e physical properties such as melting point, pour point, kinematic viscosity, oxidation stability, and lubricity were investigated and reported that low frictional values were obtained for naturally derived vegetable oils as compared to conventional fluids [33]. is article also reported that cutting fluids using vegetable oils have low cutting forces during machining.
e researcher [34] conducted an experimental investigation of the influence of water-miscible vegetable oilbased machining fluid on the life of the cutting tool during machining of Ti6Al4V. is paper reported that the wear of the cutting tool can be decreased by maintaining a low machining speed, feed rate, depth of cut, and cutting fluid concentration of 10%.Many researchers [35][36][37][38] conducted a comparative study of mineral oil-based machining fluid with vegetable oil-based fluid and found that traditional machining fluid can be substituted by vegetable-based machining fluids because mineral cutting fluids are toxic and harmful to aquatic life during disposal of cutting fluid.An investigation into the machining of the AISI4340 using various machining fluids like canola oil, coconut oil, and soybean oil was carried out.It is observed that canola oil is a superior machining fluid in comparison to coconut and soybean oil due to reduced wear and increased life of the cutting tool used in the machining operation [39,40].Whereas the authors [41,42] performed a study on turning operation of AISI4340 using Karanja oil-based machining fluids and reported that the chip thickness and tool wear decreased in comparison with the traditional machining fluids.Moreover, a comparative study using biodegradable and traditional machining fluids in the turning of AISI 1050 steel was performed.It is reported that the vegetable oilbased machining fluid accomplished superior cutting force during machining and wettability angle [43].However, researchers [44,45] investigated to estimate the influence of mixing of solid lubricant in vegetable-based machining fluid while machining Inconel 718.e author has observed that the mixing of MoS 2 enhances tool life to a great extent and also enhances the machined surface features with a lower value of cutting forces during machining.Researchers [46,47] discussed several aspects of the turning process, such as surface quality and tool life, that can be improved with the MQL system.
ese articles explain MQL techniques by implementing them.It could be beneficial to the industry in terms of cost, environmental impact, and safety, especially for metalworking companies.
From this study, it can be concluded that sustainability and exergy analysis during dry turning operations show that the exergy loss reduces with an increase in the machining speed until it attains the least value.e wear of the cutting tool can be decreased by maintaining a low machining speed, feed rate, depth of cut, and cutting fluid concentration of 10%.Traditional machining fluids can be substituted by vegetable-based machining fluids because mineral cutting fluids are toxic and harmful to aquatic life.

Milling.
e influence of various input parameters on the machining force and tool life in the milling of Inconel 718 under dry and MQL conditions was examined [48,49].It is observed that with the application of the MQL technique during the machining operation, a remarkable improvement in the cutting force is exerted and the tool life is extended.
e author also presented that the MQL technique with biodegradable machining fluids can be a substitute for dry machining.
Kuram et al. [50] investigated machinability during milling of AISI 304 in terms of specific energy, surface irregularity, and life of the cutting tool.e author has developed a mathematical model to optimize specific energy, surface irregularity, and life of the cutting tool and concluded that these prepared machining fluids can be utilized as a replacement to the traditional machining fluids in terms of performance and environmental impact.Burton et al. [51] investigated the performance of vegetable-based machining fluids and observed less surface irregularity, cutting force, and chip thickness as compared to traditional machining fluids.Whereas, the influence of various types of vegetable oil-based machining fluids such as sunflower, coconut, palm, and soybean oil in comparison with conventional cutting fluids in the milling of 7075-T6 hybrid aluminum metal matrix composite was explored [52].It is reported that palm oil-based machining fluid results in lower cutting force and minimum vibration in comparison with other types of biodegradable machining fluids.Moreover, a comparative study on the use of different biodegradable oil-based machining fluids in the milling of AISI 1045 steel under the MQL technique was performed [53].erefore, it is concluded that the MQL technique with biodegradable machining fluids can be a substitute for dry machining.Cottonseed and canola oil-based machining fluids have better cooling ability and higher tool life along with no environmental impact.

Grinding.
Alves and Oliveira et al. [54] performed grinding operations on SAE 8640 with a vitrified CBN wheel.It was found that wheel wear and machined surface irregularity were less by using biodegradable machining fluid in comparison with conventional fluid.e chemical analysis of the formulated fluid shows that it is nontoxic and biodegradable with no corrosion inhibiting characteristics.e influence of various machining fluids during surface grinding of Ti-6Al-4V, WT-22, and TIGER 5 was performed [55].Various machining oils include emulsion, oil, dry grinding, propylene glycol, micro-3000, eco cut Mikro 82, and bio cut 3000.e author has concluded that by using propylene glycol, cutting fluid is easily accessible, less harmful, environmentally friendly, and has a lower value of cutting force with less surface damage and deformation.Whereas, Wang et al. [56] investigated the surface grinding of nickel-based alloy GH4169 using several biodegradable machining fluids such as soybean, peanuts, maize, rapeseed, palm, castor, and sunflower oil.
e author has reported that castor oil-based cutting fluid results in excellent surface morphology and the least surface irregularity (Ra � 0.366 and RSM � 0.324) with less friction and specific grinding energy.
A comparative study of the surface grinding of Ti6Al4V using dry and biodegradable machining fluids was carried out and concluded that vegetable-based fluids result in superior surface quality than dry grinding with the least value of Ra at various grinding depths [57].In addition, the author has also reported that surface irregularities such as side flow, plastic deformation, and redeposition exist in dry and fluid grinding.
Using biodegradable machining fluids such as propylene glycol, the cutting fluid is less harmful and environmentally friendly.It has a lower value of cutting force with less surface damage and deformation.It can also be concluded that vegetable-based fluids result in superior surface quality, less friction, and specific grinding energy.

Drilling.
From the previous investigations, it was observed that the chips removal from inside the drilled hole had difficulties.Moreover, the cutting fluids also extend the life of tools and improve the efficiency of manufacturing Advances in Materials Science and Engineering processes by cooling and lubricating the work surface.Previous research articles also reported that better dimensional precision and quality of the surface can be produced.A comparative study to estimate the performance of machining fluids in the drilling of AA1050 and turning of AA 6262-T6 aluminum alloy was carried out [58].It is reported that during the machining of AA 1050-O aluminum, the increasing flow rate of the mist results in higher torque and lower feed force while surface finish remains unaffected.However, in the turning of AA 6162-T6 aluminum alloy, better machinability was seen such as lower surface irregularity and machining force at higher cutting speeds with lower values of feed rate and depth of cut.However, Bhowmick and Alpas [59] carried out a comparative study on the drilling of Al-6% Si (319 Al) alloy under MQL and conventional lubrication techniques.e experimental result shows that under the MQL technique, the drilling torque is reduced significantly as compared to conventional lubrication techniques.Whereas, Kuram et al. [60] performed a comparative experimental investigation using biodegradable and conventional machining fluids to estimate cutting force and surface irregularity in the drilling of stainless steel 304 (SS304) with an HSS tool.It is reported that the application of biodegradable cutting fluids results in lower values of thrust force, surface roughness, and negligible tool wear as compared to conventional cutting fluids.Sharma and Sidhu [61] investigated drilling operations on AISI D2 steel using biodegradable machining fluids under dry and near-dry machining techniques.e presented results indicate that near-dry machining has enhanced machinability than dry drilling in terms of surface irregularity and tool work interface temperature.In addition, we used neem and Mahua oil-based machining fluids in the drilling of AISI 304L and also performed statistical analysis to obtain the optimal values of surface irregularity, thrust force, and temperature in machining.ese parameters were found to be optimum in Mahua-based cutting fluid [62].Whereas, Kuram and Ozcelik [63] performed prediction of surface irregularity and machining force in the drilling of AISI 304 with biodegradable machining fluids using fuzzy logic and regression model.
e results were compared with the established fuzzy logic model, regression model, and experimental values and reported that the fuzzy logic model is more accurate than the regression model.erefore, the fuzzy logic model can be recommended for the prediction of the surface irregularity and thrust force.Whereas a comparison of palm oil and synthetic ester for drilling Ti6Al4V using the MQL technique revealed that palm oil outperformed synthetic ester in terms of specific cutting energy, power, and cutting force [64].As a result, utilizing the MQL approach, palm oil can be employed as an alternative to a synthetic ester.
e removal of chips from the drilled hole has been a problem in the past.In order to extend the life of the tools and increase the efficiency of manufacturing processes, cutting fluids must be chosen carefully.Aside from these advantages, cutting fluids with proper machinability have lower surface irregularity and machining force at higher cutting speeds with lower values of feeding rate, cutting speed, and depth of cut.

Application of Eco-Friendly Nanofluids
ese cutting fluids are made up of nanoparticles and traditional cutting fluids.By incorporating nanoparticles into cutting fluids, features such as wettability, convective heat transfer coefficient, and lubricating qualities are improved.High thermal conductivity, a small thermal expansion coefficient, good heat carrying capacity, good wear resistance, and minimal friction are all characteristics of nano cutting fluids.Nanoparticle additions also increase load-carrying capacity, reduce wear, and reduce friction.Metal oxides, nitrides, ceramics, silicates, carbides, and nonoxide ceramics are some of the most frequent nanoparticles.Heat transfer is improved, wettability is improved, and tribiological characteristics are improved with nano-fluids.

4.1.
Turning.[65] carried out an experimental study on the thermal behaviour of graphene oxide enhanced nano-fluids.
e thermal conductivity of the graphene oxide nano machining fluid increased by 71 percent when compared to traditional machining fluids due to improved heat transfer capabilities, according to the author.Jamil et al. [66] employed a vegetable-based hybrid nano-fluid including Al 2 O 3 and CNT nanoparticles that was combined with vegetable oil.In comparison to cryogenic cooling, average surface irregularity and cutting force were lowered by 8.72 percent and 11.8 percent, respectively, according to the stated data.Sahu et al. [67] employed a mixed nano-fluid of multiwalled carbon nanotubes (MWCNTs) to evaluate the performance of Ti6Al4V turning.In comparison to traditional cooling techniques, the performance of eco-friendly nano-cutting reveals reduced chip thickness as well as improved cooling and lubricating capabilities [68,69].Padmini et al. [70,71] evaluated machining force, surface irregularity, temperature, and tool wear during machining of AISI 1045 steel using nano-molybdenum di-sulfide (nMoS 2 ) in coconut (CC), sesame (SS), and canola (CAN) oil-based cutting fluids.In comparison to dry machining, the author claims that cutting force, surface irregularity, temperature, and tool wear are reduced by 37 percent, 39 percent, 21 percent, and 44 percent, respectively.Using a turning operation, the properties of different nano-cutting fluids, including aluminium oxide (Al 2 O 3 ), molybdenum disulfide (MoS 2 ), and graphite, were examined under minimal quantity lubrication (MQL) conditions on Inconel-800 alloy.Surface roughness, cutting forces, and tool wear were all used to evaluate the machining process' performance.e addition of MoS 2 to cutting fluids is said to improve the cooling and lubrication of the workpiece and tool during the machining process [72].Under the MQL approach, the effect of biodegradable nanomachining fluids on machining force, surface irregularity, and tool wear in the turning of Inconel superalloy is investigated.In comparison to conventional machining fluids, MoS 2 and graphite-based nano-fluids produce better outcomes at greater cutting rates, according to this study.

6
Advances in Materials Science and Engineering Yildirim et al. [73] sought to investigate the impact of dry, MQL, and nano-MQL cooling and lubrication methods on surface irregularity, tool life, tool wear, and temperature in the turning of Inconel 625.e author claims that adding nanoparticles into cutting fluids significantly enhances the previously listed performance characteristics.However, the author [74,75] discusses his research into the production of carbon nanotube-based nanofluids for improved machining efficiency over traditional cutting fluids.Different nanofluid samples were produced, and their appropriateness was assessed.e prepared carbon nanotube-based cutting fluids have higher thermal conductivity and reduced viscosity, according to the findings of this study.In addition, the author conducted comparison research by milling 42CrMo4 hardened steel utilizing a dry cutting, with conventional and nanofluid.Cutting performance was enhanced by a reduction of 29 percent in cutting temperature, 34 percent in surface roughness, 33 percent in cutting force, and 39 percent in tool wear when nano-cutting fluids were used.e impact of various vegetable-based nano machining fluids on tool wears is shown in Figure 5.

Milling.
To assess tool wear and surface irregularity, Uysal et al. [76] milled AISI 420 steels with vegetable-based hybrid nanomachining fluids.It is reported that less good surface finish and less tool wear were observed upon application of the optimal supply of the cutting fluids during the machining operation.In contrast, Uysal [77] investigated tool failure in the milling of SS304 utilizing biodegradable nano machining fluid.It can be inferred that by using nano machining fluid, many forms of tool wear are greatly decreased.However, Prasad et al. [78] investigated the effects of nano-cutting fluids on surface irregularity and interface temperature to determine ideal values.e Taguchi technique was used to determine the ideal values for these parameters, and the reported optimal parameters are 510 rpm spindle speed, 16 mm/min feed rate, and 0.6 mm depth of cut for minimal surface irregularity.Figure 6 depicts the effects of various machining fluids on tool wear.
Moreover, Settu and Nandagopal [79] noted that the current research investigates the machining of EN8 steel utilizing various cooling and lubrication techniques such as without using cutting fluids, with oil mixed in water, and eco-friendly nano-cutting fluids.e nanofluids were produced by the mixing of refined corn-oil and CuO nanoparticles in a mixing ratio of 0.3 percent by weight followed by ultrasonication.Furthermore, to find the optimal machining parameters, the Taguchi and ANOVA techniques were employed.
e tool wear and surface finish during machining were evaluated using typical machining parameters.It was discovered that the eco-friendly nanocutting fluids have better machining performance than dry and mineral oil-based cutting fluids.[80] investigated the microgrinding process with nano-fluid.e results reveal that when nanoparticles are added to the machining fluid, the grinding force is reduced greatly, and the surface quality is improved due to the greater lubricating qualities.In addition, the author concluded that nano-diamond particles outperformed nano Al2O3 in terms of reducing the magnitude of the grinding force.e major goal of the research was to find the best combination of nanoparticles and eco-friendly oil for grinding Ni-based alloys with the least amount of lubrication [81].An experimental investigation was conducted on a variety of ecofriendly oils combined with castor oil.Grinding force, specific grinding energy, and surface roughness were used to evaluate the lubricating qualities of the prepared cutting fluids.According to reports, soybean oil-based cutting fluid outperforms castor oil and other mixed base oils when it comes to machining.Due to its exceptional lubricating capabilities, the lubricating capability of the oil was also examined by adding MoS2 nanoparticles.Whereas, Li et al. [82] used six different types of nanoparticles in palm oilbased cutting fluid to perform surface grinding on Ni-based alloys and reported that inclusion of carbon nanotube in the cutting fluid results in better cooling properties as compared to other nanoparticles.Important physical properties of nanofluids, such as viscosity, surface tension, and contact angle, are also being investigated to see how they affect cooling performance.

Grinding. Using MQL techniques, Lee et al
e performance of grinding parameters such as coefficient of friction, machining forces, temperature, and power consumption was evaluated in an experiment on surface grinding and reported to have good surface finish and less friction coefficient using the MQL approach [83].Chaudhari et al. [84] used an optimization technique to explore the impact of nano-fluids on surface grinding.In comparison to traditional approaches, the surface irregularity is reduced by 14% in this inquiry.However, Nandakumar et al. [85] used the MQL approach to experiment with surface grinding of Al Matrix Composites supplemented with nano-SiC.It is reported that the cutting force applied and induced temperature decrease as a result of the use of nano-machining fluids.Figure 7 shows the effect of various machining fluids on surface roughness.

Drilling.
Using various cooling and lubrication methods such as compressed air lubrication, pure MQL, and Nanofluid MQL, Nam et al. [86] examined the performance of drilling parameters in terms of drilling force and torque, hole quality, and several holes.When compared to conventional cooling and lubricating methods, the use of nano-fluids under the MQL methodology significantly improves the surface quality of the fabricated holes [87].e use of nano machining fluid resulted in considerable reductions in flank wear and surface roughness.In contrast, Liew et al. [88] published a study comparing the effects of carbon nanofiberbased nano cutting fluid and standard cooling on SS304 drilling.e burr formation, dimensional correctness, and surface polish of the produced hole were all used to evaluate the drilling's performance.e findings show that a carbon nanofiber-based nano cutting fluid minimizes surface roughness and burr development while also improving hole Advances in Materials Science and Engineering precision.While Babu and Muthukrishnan [89] used copper nanoparticle mixed eco-friendly cutting uids under MQL and traditional machining uids for drilling of AA5052 alloy, it is reported that the application of eco-friendly cutting uids results in less tool wear and good surface nish.Furthermore, Nam and Lee [90] used biodegradable nano machining uids to microdrill Ti6Al4V under MQL.
e results show that using a vegetable-based nano cutting uid reduces thrust force and torque while also e ciently reducing burrs in produced holes at a lower feed rate.Figure 8 shows the in uence of concentration of nanoparticles on average values of torque and thrust force with various biodegradable nano-uids during hole drilling, whereas Figure 9 shows the in uence of concentration of nanoparticles on surface roughness.
Lee et al. [91] reported an investigation on mesoscale grinding using the MQL technique for supply of cutting uids and reported that the nano-uid MQL technique can Average Thrust Force (N)     3 and a summary of the literature review on vegetable oil-based nano cutting fluids listed in Table 4.

Conclusions
e author offered a summary of previous and current research carried out in various machining processes using vegetable oil-based machining fluids (including vegetablebased nano machining fluids).Suitability and application of different eco-friendly cutting fluids with and without mixing of nanoparticles in the cutting fluids.Various dimensions of the sustainability of the eco-friendly cutting fluids were explored in terms of their social, economic, environmental, and technological dimensions.Different preparation steps and methods for the preparation of ecofriendly cutting fluids are introduced, along with testing and characterization.
e article extensively discussed applications of eco-friendly cutting fluids for turning, milling, grinding, and drilling operations for different workpiece materials.Various cutting fluids prepared and used during machining include sunflower oil, coconut oil, palm oil, soybean oil, cottonseed, groundnut, jatropha, rapeseed, canola, and Karanja.Different nanoparticles mixed in cutting fluids include Al 2 O 3 , CNT, nMoS 2 , CuO, SiC, graphene, hBN, ZnO, and diamond particles.e cooling and lubrication techniques employed during machining include dry, near dry, flood, mist flow, chilled air, cryogenic, and MQL. e input parameters selected for the machinability analysis of the workpiece were explored in terms of cutting velocity, feed rate, depth of cut, the power required, amount of cooling, and lubricant supplied.Whereas, the output parameters were explored in terms of material removal rate, tool life, tool wear, cutting force, cutting zone temperature, chip thickness, and surface roughness of the machined workpiece.
Compared to the standard vegetable-based machining fluids, nanoparticle enhanced in vegetable oil-based machining fluids greatly improves thermal and tribological properties, according to these literature.e following are some of the key takeaways from the literature review: (i) Better surface finish and machining capability at higher cutting speeds as compared to conventional cutting fluids.(ii) Enhanced tool life, less surface irregularity, and improved accuracy due to less heat generation using eco-friendly cutting fluids.(iii) Application of vegetable oil-based cutting fluids results in low cutting forces during machining.(iv) Low tool wear and less chip thickness can be achieved by maintaining a low machining speed, feed rate, depth of cut, and cutting fluid concentration of 10%.
(v) e use of eco-friendly cutting fluids results in less friction, specific grinding energy, surface damage, and deformation during the grinding process.(vi) Reduced drilling torque, negligible tool wear, and less specific cutting energy are required during drilling operations using eco-friendly cutting fluids.(vii) Eco-friendly nano machining fluids exhibit enhanced ability to dissipate heat and tribological properties.(viii) Surface irregularity, tool wear, machining force, power consumption, and interface temperature are all reduced dramatically when nanoparticles are mixed in the base fluids (vegetable oil).

Future Work Recommendations
e focus of this review paper was to investigate the influence of eco-friendly cutting operations on the use of different machining operations.
ese investigations also explored used only one kind of nanoparticles mixed in an eco-friendly cutting fluid.Greater research can be performed into hybrid biodegradable nano-fluids in which more than one type of nanoparticles is present while preparing ecofriendly cutting fluids.Applications of the hybrid nanocutting fluids in different machining operations can be performed and their influence can also be investigated.Furthermore, the effect of the shape and size of the nanoparticles in the base fluids on the machining fluids' performance can be examined.

Figure 8 :Figure 9 :
Figure 8: In uence of concentration of nanoparticle on average values of torque and thrust force with various vegetable-based nano-uids during hole drilling [90].

Table 1 :
Basic parameters considered while selecting machining uids.

Table 3 :
Summary of the literature review on vegetable-based cutting fluids.

Table 4 :
Summary of the literature review on vegetable Oils based nano cutting fluids.

Table 4 :
Continued.Advances in Materials Science and Engineering greatly reduce grinding forces and surface roughness.Furthermore, smaller nano-diamond particles may be more advantageous for creating superior grinding surfaces.A summary of the literature review on vegetable-based cutting fluids listed in Table