Grindability Evaluation of Ultrasonic Assisted Grinding of Silicon Nitride Ceramic Using Minimum Quantity Lubrication Based SiO_(2)Nanofluid

Minimum quantity Lubrication(MQL)is a sustainable lubrication system that is famous in many machining systems.It involve the spray of an infinitesimal amount of mist-like lubricants during machining processes.The MQL system is affirmed to exhibit an excellent machining performance,and it is highly economical.The nanofluids are understood to exhibit excellent lubricity and heat evacuation capability,compared to pure oil-based MQL system.Studies have shown that the surface quality and amount of energy expended in the grinding operations can be reduced considerably due to the positive effect of these nanofluids.This work presents an experimental study on the tribological performance of SiO_(2)nanofluid during grinding of Si_(3)N_(4)ceramic.The effect different grinding modes and lubrication systems during the grinding operation was also analyzed.Different concentrations of the SiO_(2)nanofluid was manufactured using canola,corn and sunflower oils.The quantitative evaluation of the grinding process was done based on the amount of grinding forces,specific grinding energy,frictional coefficient,and surface integrity.It was found that the canola oil exhibits optimal lubrication performance compared to corn oil,sunflower oil,and traditional lubrication systems.Additionally,the introduction of ultrasonic vibrations with the SiO_(2)nanofluid in MQL system was found to reduce the specific grinding energy,normal grinding forces,tangential grinding forces,and surface roughness by 65%,57%,65%,and 18%respectively.Finally,regression analysis was used to obtain an optimum parameter combinations.The observations from this work will aid the smooth transition towards ecofriendly and sustainable machining of engineering ceramics.

Tribological Performance of Different Concentrations of Al_(2)O_(3)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.Al_(2)O_(3)nanoparticles improve not only the heat transfer capacity but also the lubrication performance.The physical and chemical proper-ties of nanofluid change when Al_(2)O_(3)nanoparticles are added.However,the effects of the concentration of nanofluid on lubrication performance remain unknown.Furthermore,the mechanisms of interaction between Al_(2)O_(3)nanoparti-cles and cottonseed oil are unclear.In this research,nanofluid is prepared by adding different mass concentrations of Al_(2)O_(3)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/mm^(3)),and the roughness value is the lowest(1.63μm)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 proper-ties are the best under 0.5 wt%.This research investigates the intercoupling mechanisms of Al_(2)O_(3)nanoparticles and cottonseed base oil,and acquires the optimal Al_(2)O_(3)nanofluid concentration to receive satisfactory tribological properties.

Tribological Mechanism of Graphene and Ionic Liquid Mixed Fluid on Grinding Interface under Nanofluid Minimum Quantity Lubrication

Graphene has superhigh thermal conductivity up to 5000 W/(m·K),extremely thin thickness,superhigh mechanical strength and nano-lamellar structure with low interlayer shear strength,making it possess great potential in mini-mum quantity lubrication(MQL)grinding.Meanwhile,ionic liquids(ILs)have higher thermal conductivity and better thermal stability than vegetable oils,which are frequently used as MQL grinding fluids.And ILs have extremely low vapor pressure,thereby avoiding film boiling in grinding.These excellent properties make ILs also have immense potential in MQL grinding.However,the grinding performance of graphene and ionic liquid mixed fluid under nano-fluid minimum quantity lubrication(NMQL),and its tribological mechanism on abrasive grain/workpiece grinding interface,are still unclear.This research firstly evaluates the grinding performance of graphene and ionic liquid mixed nanofluids(graphene/IL nanofluids)under NMQL experimentally.The evaluation shows that graphene/IL nanofluids can further strengthen both the cooling and lubricating performances compared with MQL grinding using ILs only.The specific grinding energy and grinding force ratio can be reduced by over 40%at grinding depth of 10μm.Work-piece machined surface roughness can be decreased by over 10%,and grinding temperature can be lowered over 50℃at grinding depth of 30μm.Aiming at the unclear tribological mechanism of graphene/IL nanofluids,molecular dynamics simulations for abrasive grain/workpiece grinding interface are performed to explore the formation mechanism of physical adsorption film.The simulations show that the grinding interface is in a boundary lubrication state.IL molecules absorb in groove-like fractures on grain wear flat face to form boundary lubrication film,and graphene nanosheets can enter into the grinding interface to further decrease the contact area between abrasive grain and workpiece.Compared with MQL grinding,the average tangential grinding force of graphene/IL nanofluids can decrease up to 10.8%.The interlayer shear effect and low interlayer shear strength of graphene nanosheets are the principal causes of enhanced lubricating performance on the grinding interface.EDS and XPS analyses are further carried out to explore the formation mechanism of chemical reaction film.The analyses show that IL base fluid happens chemical reactions with workpiece material,producing FeF_(2),CrF_(3),and BN.The fresh machined surface of workpiece is oxidized by air,producing NiO,Cr_(2)O_(3) and Fe_(2)O_(3).The chemical reaction film is constituted by fluorides,nitrides and oxides together.The combined action of physical adsorption film and chemical reaction film make graphene/IL nano-fluids obtain excellent grinding performance.

Electrostatic atomization minimum quantity lubrication machining:from mechanism to application

Metal cutting fluids(MCFs)under flood conditions do not meet the urgent needs of reducing carbon emission.Biolubricant-based minimum quantity lubrication(MQL)is an effective alternative to flood lubrication.However,pneumatic atomization MQL has poor atomization properties,which is detrimental to occupational health.Therefore,electrostatic atomization MQL requires preliminary exploratory studies.However,systematic reviews are lacking in terms of capturing the current research status and development direction of this technology.This study aims to provide a comprehensive review and critical assessment of the existing understanding of electrostatic atomization MQL.This research can be used by scientists to gain insights into the action mechanism,theoretical basis,machining performance,and development direction of this technology.First,the critical equipment,eco-friendly atomization media(biolubricants),and empowering mechanisms of electrostatic atomization MQL are presented.Second,the advanced lubrication and heat transfer mechanisms of biolubricants are revealed by quantitatively comparing MQL with MCF-based wet machining.Third,the distinctive wetting and infiltration mechanisms of electrostatic atomization MQL,combined with its unique empowering mechanism and atomization method,are compared with those of pneumatic atomization MQL.Previous experiments have shown that electrostatic atomization MQL can reduce tool wear by 42.4%in metal cutting and improve the machined surface Ra by 47%compared with pneumatic atomization MQL.Finally,future development directions,including the improvement of the coordination parameters and equipment integration aspects,are proposed.

Influence of Minimum Quantity Lubrication Parameters on Tool Wear and Surface Roughness in Milling of Forged Steel

The minimum quantity of lubrication（MQL） technique is becoming increasingly more popular due to the safety of environment.Moreover,MQL technique not only leads to economical benefits by way of saving lubricant costs but also presents better machinability.However,the effect of MQL parameters on machining is still not clear,which needs to be overcome.In this paper,the effect of different modes of lubrication,i.e.,conventional way using flushing,dry cutting and using the minimum quantity lubrication（MQL） technique on the machinability in end milling of a forged steel（50CrMnMo）,is investigated.The influence of MQL parameters on tool wear and surface roughness is also discussed.MQL parameters include nozzle direction in relation to feed direction,nozzle elevation angle,distance from the nozzle tip to the cutting zone,lubricant flow rate and air pressure.The investigation results show that MQL technique lowers the tool wear and surface roughness values compared with that of conventional flood cutting fluid supply and dry cutting conditions.Based on the investigations of chip morphology and color,MQL technique reduces the cutting temperature to some extent.The relative nozzle-feed position at 120°,the angle elevation of 60° and distance from nozzle tip to cutting zone at 20 mm provide the prolonged tool life and reduced surface roughness values.This fact is due to the oil mists can penetrate in the inner zones of the tool edges in a very efficient way.Improvement in tool life and surface finish could be achieved utilizing higher oil flow rate and higher compressed air pressure.Moreover,oil flow rate increased from 43.8 mL？h to 58.4 mL？h leads to a small decrease of flank wear,but it is not very significant.The results obtained in this paper can be used to determine optimal conditions for milling of forged steel under MQL conditions.

Performance evaluation of minimum quantity lubrication by vege-table oil in terms of cutting force,cutting zone temperature,tool wear,job dimension and surface finish in turning AISI-1060 steel

In all machining processes, tool wear is a natural phenomenon and it leads to tool failure. The growing demands for high productivity of machining need use of high cutting velocity and feed rate. Such machining inherently produces high cutting temperature, which not only reduces tool life but also impairs the product quality. Metal cutting fluid changes the performance of machining operations because of their lubrication, cooling and chip flushing functions, but the use of cutting fluid has become more problematic in terms of both employee health and environmental pollution. The minimization of cutting fluid also leads to economical benefits by way of saving lubricant costs and workpiece/tool/machine cleaning cycle time. The concept of minimum quantity lubrication (MQL) has been suggested since a decade ago as a means of addressing the issues of environmental intru- siveness and occupational hazards associated with the airborne cutting fluid particles on factory shop floors. This paper deals with experimental investigation on the role of MQL by vegetable oil on cutting temperature, tool wear, surface roughness and dimen- sional deviation in turning AISI-1060 steel at industrial speed-feed combinations by uncoated carbide insert. The encouraging results include significant reduction in tool wear rate, dimensional inaccuracy and surface roughness by MQL mainly through reduction in the cutting zone temperature and favorable change in the chip-tool and work-tool interaction.

Prediction model of volume average diameter and analysis of atomization characteristics in electrostatic atomization minimum quantity lubrication

Minimum quantity lubrication(MQL)is a relatively efficient and clean alternative to flooding workpiece machining.Electrostatic atomization has the merits of small droplet diameter,high uniformity of droplet size,and strong coating,hence its superiority to pneumatic atomization.However,as the current research hotspot,the influence of jet parameters and electrical parameters on the average diameter of droplets is not clear.First,by observing the shape of the liquid film at the nozzle outlet,the influence law of air pressure and voltage on liquid film thickness(h)and transverse and longitudinal fluctuations are determined.Then,the mathematical model of charged droplet volume average diameter(VAD)is constructed based on three dimensions of the liquid film,namely its thickness,transverse wavelength(λ_(h)),and longitudinal wavelength(λ_(z)).The model results under different working conditions are obtained by numerical simulation.Comparisons of the model results with the experimental VAD of the droplet confirm the error of the mathematical model to be less than 10%.The droplet diameter distribution span value Rosin–Rammler distribution span(R.S)and percentage concentrations of PM10(particle size of less than 10μm)/PM2.5(particle size of less than 2.5μm)under different working conditions are further analyzed.The results show that electrostatic atomization not only reduces the diameter distribution span of atomized droplets but also significantly inhibits the formation of PM10 and PM2.5 fine-suspension droplets.When the air pressure is 0.3 MPa,and the voltage is 40 kV,the percentage concentrations of PM10 and PM2.5 can be reduced by 80.72%and 92.05%,respectively,compared with that under the pure pneumatic atomization condition at 0.3 MPa.

Tribological mechanism of carbon group nanofluids on grinding interface under minimum quantity lubrication based on molecular dynamic simulation

Carbon group nanofluids can further improve the friction-reducing and anti-wear properties of minimum quantity lubrication(MQL).However,the formation mechanism of lubrication films generated by carbon group nanofluids on MQL grinding interfaces is not fully revealed due to lack of sufficient evidence.Here,molecular dynamic simulations for the abrasive grain/workpiece interface were conducted under nanofluid MQL,MQL,and dry grinding conditions.Three kinds of carbon group nanoparticles,i.e.,nanodiamond(ND),carbon nanotube(CNT),and graphene nanosheet(GN),were taken as representative specimens.The[BMIM]BF4 ionic liquid was used as base fluid.The materials used as workpiece and abrasive grain were the single-crystal Ni–Fe–Cr series of Ni-based alloy and single-crystal cubic boron nitride(CBN),respectively.Tangential grinding force was used to evaluate the lubrication performance under the grinding conditions.The abrasive grain/workpiece contact states under the different grinding conditions were compared to reveal the formation mechanism of the lubrication film.Investigations showed the formation of a boundary lubrication film on the abrasive grain/workpiece interface under the MQL condition,with the ionic liquid molecules absorbing in the groove-like fractures on the grain wear’s flat face.The boundary lubrication film underwent a friction-reducing effect by reducing the abrasive grain/workpiece contact area.Under the nanofluid MQL condition,the carbon group nanoparticles further enhanced the tribological performance of the MQL technique that had benefited from their corresponding tribological behaviors on the abrasive grain/workpiece interface.The behaviors involved the rolling effect of ND,the rolling and sliding effects of CNT,and the interlayer shear effect of GN.Compared with the findings under the MQL condition,the tangential grinding forces could be further reduced by 8.5%,12.0%,and 14.1%under the diamond,CNT,and graphene nanofluid MQL conditions,respectively.

Minimum quantity lubrication machining of aeronautical materials using carbon group nanolubricant: From mechanisms to application

It is an inevitable trend of sustainable manufacturing to replace flood and dry machining with minimum quantity lubrication(MQL)technology.Nevertheless,for aeronautical difficult-tomachine materials,MQL couldn’t meet the high demand of cooling and lubrication due to high heat generation during machining.Nano-biolubricants,especially non-toxic carbon group nano-enhancers(CGNs)are used,can solve this technical bottleneck.However,the machining mechanisms under lubrication of CGNs are unclear at complex interface between tool and workpiece,which characterized by high temperature,pressure,and speed,limited its application in factories and necessitates in-depth understanding.To fill this gap,this study concentrates on the comprehensive quantitative assessment of tribological characteristics based on force,tool wear,chip,and surface integrity in titanium alloy and nickel alloy machining and attempts to answer mechanisms systematically.First,to establish evaluation standard,the cutting mechanisms and performance improvement behavior covering antifriction,antiwear,tool failure,material removal,and surface formation of MQL were revealed.Second,the unique film formation and lubrication behaviors of CGNs in MQL turning,milling,and grinding are concluded.The influence law of molecular structure and micromorphology of CGNs was also answered and optimized options were recommended by considering diverse boundary conditions.Finally,in view of CGNs limitations in MQL,the future development direction is proposed,which needs to be improved in thermal stability of lubricant,activity of CGNs,controllable atomization and transportation methods,and intelligent formation of processing technology solutions.

Milling surface roughness for 7050 aluminum alloy cavity influenced by nozzle position of nanofluid minimum quantity lubrication

In nanofluid minimum quantity lubrication(NMQL)milling of aviation aluminum alloy,it is the bottleneck problem to adjust the position parameters(target distance,incidence angle,and elevation angle)of the nozzle to improve the surface roughness of milling,which has large and uncontrollable errors.In this paper,the influence law of milling cutter speed,helical angle,and cavity shape on the flow field around the milling cutter was studied,and the optimal nozzle profile parameters were obtained.Using 7050 aluminum alloy as the workpiece material,the milling experiment of the NMQL cavity was conducted by utilizing cottonseed oil-based Al2 O3 nanofluid.Results show that the high velocity of the surrounding air flow field and the strong gas barrier could be attributed to high rotating velocities of the milling cutter.The incidence angle of the nozzle was consistent with the helical angle of the milling cutter,the target distance was appropriate at 25–30 mm,and the elevation angle was suitable at 60°–65°.The range and variance analyses of the signal-to-noise ratio of milling force and roughness were performed,and the chip morphology was observed and analyzed.The results show that the optimal combination of nozzle position parameters was the target distance of 30 mm,the incidence angle of 35°,and the elevation angle of 60°.Among these parameters,target distance had the largest impact on cutting performance with a contribution rate of more than 55%,followed by incidence angle and elevation contribution rate.Analysis by orthogonal experiment revealed that the nozzle position parameters were appropriate,and Ra(0.087 lm)was reduced by 30.4%from the maximum value(0.125 lm).Moreover,Rsm(0.05 mm)was minimum,which was 36%lower than that of the seventh group(Rsm=0.078 mm).

Cryogenic minimum quantity lubrication machining: from mechanism to application

Cutting fluid plays a cooling-lubrication role in the cutting of metal materials.However,the substantial usage of cutting fluid in traditional flood machining seriously pollutes the environment and threatens the health of workers.Environmental machining technologies,such as dry cutting,minimum quantity lubrication(MQL),and cryogenic cooling technology,have been used as substitute for flood machining.However,the insufficient cooling capacity of MQL with normal-temperature compressed gas and the lack of lubricating performance of cryogenic cooling technology limit their industrial application.The technical bottleneck of mechanical-thermal damage of difficult-to-cut materials in aerospace and other fields can be solved by combining cryogenic medium and MQL.The latest progress of cryogenic minimum quantity lubrication(CMQL)technology is reviewed in this paper,and the key scientific issues in the research achievements of CMQL are clarified.First,the application forms and process characteristics of CMQL devices in turning,milling,and grinding are systematically summarized from traditional settings to innovative design.Second,the cooling-lubrication mechanism of CMQL and its influence mechanism on material hardness,cutting force,tool wear,and workpiece surface quality in cutting are extensively revealed.The effects of CMQL are systematically analyzed based on its mechanism and application form.Results show that the application effect of CMQL is better than that of cryogenic technology or MQL alone.Finally,the prospect,which provides basis and support for engineering application and development of CMQL technology,is introduced considering the limitations of CMQL.

Evaluation of surface roughness and optimization of cutting parameters in turning of AA2024 alloy under different cooling-lubrication conditions using RSM method

In the present study,the effect of reduction of cutting fluid consumption on the surface quality and tool wear was studied.Mathematical models were developed to predict the surface roughness using response surface methodology(RSM).Analysis of variance(ANOVA)was used to investigate the significance of the developed regression models.The results showed that the coefficient of determination values(R^2)for the developed models was 97.46%for dry,89.32%for flood mode(FM),and 99.44%for MQL,showing the high accuracy of fitted models.Also,under the minimum quantity lubrication(MQL)condition,the surface roughness improved by 23%−44%and 19%−41%compared with dry and FM,respectively,and the SEM images of machined surface proved the statement.The prepared SEM images of tool rake face also showed a considerable decrease in adhesion wear.Built-up edge and built-up layer were the two main products of the adhesion wear,and energy-dispersive X-ray spectroscopy(EDX)analysis of specific points on the tool faces helped to discover the chemical compositions of adhered materials.By changing dry and FM to MQL mode,dominant mechanism of tool wear in machining aluminum alloy was significantly decreased.Breakage wear that led to early failure of cutting edge was also controlled by MQL technique.

Optimization of cutting parameters with Taguchi and grey relational analysis methods in MQL-assisted face milling of AISI O2 steel

This study aims to examine the usability of environmentally harmless vegetable oil in the minimum quantity of lubrication(MQL)system in face milling of AISI O2 steel and to optimize the cutting parameters by different statistical methods.Vegetable oil was preferred as cutting fluid,and Taguchi method was used in the preparation of the test pattern.After testing with the prepared test pattern,cutting performance in all parameters has been improved according to dry conditions thanks to the MQL system.The highest tool life was obtained by using cutting parameters of 7.5 m cutting length,100 m/min cutting speed,100 mL/h MQL flow rate and 0.1 mm/tooth feed rate.Optimum cutting parameters were determined according to the Taguchi analysis,and the obtained parameters were confirmed with the verification tests.In addition,the optimum test parameter was determined by applying the gray relational analysis method.After using ANOVA analysis according to the measured surface roughness and cutting force values,the most effective cutting parameter was observed to be the feed rate.In addition,the models for surface roughness and cutting force values were obtained with precisions of 99.63%and 99.68%,respectively.Effective wear mechanisms were found to be abrasion and adhesion.

Performance evaluation of nanofluid-based minimum quantity lubrication grinding of Ni-Cr alloy under the influence of CuO nanoparticles

In machining processes,researchers are actively engaged in exploring minimum quantity lubrication(MQL)as a possible alternative to traditional flood cooling owing to economic and ecological concerns.The search for ecologically safe lubricants has attracted the attention of scientists looking to use vegetable oil as a lubricant.The nanofluid MQL technique with biodegradable oils as the base is a relatively new method with the potential to replace mineral oils.In the present study,the grinding of Inconel-718 alloy was investigated using nanofluid MQL(NFMQL)with biodegradable oils as the base.Nanofluids are composed by dispersing 0.5%(mass fraction)and 1%(mass fraction)of CuO nanoparticles in vegetable oil.The surface morphology,G-ratio,forces,and grinding energy were examined under pure MQL,NFMQL,and dry and flood lubrication conditions.The experimental results indicated that the nanofluid MQL significantly improved the machining performance.Owing to the polishing and rolling effect of nanoparticles on the tool work interface,a surface finish under a 0.5%(mass fraction)nanofluid was found to be better than pure MQL-dry and flood lubrication conditions.The NFMQL technique with 1%(mass fraction)CuO nanoparticles with palm oil as the base helped in achieving a better evacuation of chips from the grinding zone,leading to a better surface finish with a high material removal rate along with less energy consumption compared to flood and dry grinding.

Mechanical behavior and semiempirical force model of aerospace aluminum alloy milling using nano biological lubricant

Aerospace aluminum alloy is the most used structural material for rockets,aircraft,spacecraft,and space stations.The deterioration of surface integrity of dry machining and the insufficient heat transfer capacity of minimal quantity lubrication have become the bottleneck of lubrication and heat dissipation of aerospace aluminum alloy.However,the excellent thermal conductivity and tribological properties of nanofluids are expected to fill this gap.The traditional milling force models are mainly based on empirical models and finite element simulations,which are insufficient to guide industrial manufacturing.In this study,the milling force of the integral end milling cutter is deduced by force analysis of the milling cutter element and numerical simulation.The instantaneous milling force model of the integral end milling cutter is established under the condition of dry and nanofluid minimal quantity lubrication(NMQL)based on the dual mechanism of the shear effect on the rake face of the milling cutter and the plow cutting effect on the flank surface.A single factor experiment is designed to introduce NMQL and the milling feed factor into the instantaneous milling force coefficient.The average absolute errors in the prediction of milling forces for the NMQL are 13.3%,2.3%,and 7.6%in the x-,y-,and z-direction,respectively.Compared with the milling forces obtained by dry milling,those by NMQL decrease by 21.4%,17.7%,and 18.5%in the x-,y-,and z-direction,respectively.

Experimental study of oil mist characteristics generated from minimum quantity lubrication and flood cooling

The use of metalworking fluids during machining can generate oil mist and endanger the health of workers.In order to study the characteristics and emission laws of oil mist generated by machining,this study constructed a test bench to simulate the turning process.Parameters affecting the oil mist generated in the minimum quantity lubrication(MQL)mode and flood cooling mode were studied by means of single-factor experiments,and the formation mechanisms of oil mist were analyzed.The results show that the oil mist generated by the MQL system has two main sources,the initial escape of oil mist into the air and the evaporation/condensation of oil mist.The centrifugation has almost no effect on oil mist formation in the MQL mode.The mass concentration of oil mist generated by the MQL system is proportional to the cutting oil flow rate.When the work-piece is at room temperature,increasing the air supply pressure and nozzle distance,increases the oil mist mass concentration.For the flood cooling mode,the concentration of centrifugal aerosol is linearly and positively correlated with the relative centrifugal force generated by the work-piece,and the coefficient of determination(R 2)is above 0.97.The oil mist mass concentrations in MQL mode is 8.33 mg/m^(3)~305.88 mg/m^(3).The MMD and SMD are 0.74μm to 4.42μm and 0.31μm to 2.14μm,respectively.The oil mist mass concentrations in flood cooling mode is 0.2 mg/m^(3)~22.42 mg/m^(3).The MMD and SMD are 1.81μm to 6.58μm and 0.45μm to 5.13μm,respectively.

Nano-enhanced biolubricant in sustainable manufacturing:From processability to mechanisms

To eliminate the negative effect of traditional metal-working fluids and achieve sustainable manufacturing,the usage of nano-enhanced biolubricant(NEBL)is widely researched in minimum quantify lubrication(MQL)machining.It's improved tool wear and surface integrity have been preliminarily verified by experimental studies.The previous review papers also concluded the major influencing factors of processability including nano-enhancer and lubricant types,NEBL concentration,micro droplet size,and so on.Nevertheless,the complex action of NEBL,from preparation,atomization,infiltration to heat transfer and anti-friction,is indistinct which limits preparation of process specifications and popularity in factories.Especially in the complex machining process,in-depth understanding is difficult and meaningful.To fll this gap,this paper concentrates on the comprehensive quantitative assessment of processability based on tribological,thermal,and machined surface quality aspects for NEBL application in turning,milling,and grinding.Then it attempts to answer mechanisms systematically considering multi-factor influence of molecular structure,physicochemical properties,concentration,and dispersion.Firstly,this paper reveals advanced lubrication and heat transfer mechanisms of NEBL by quantitative comparison with biolubricant-based MQL machining.Secondly,the distinctive filmformation,atomization,and infiltration mechanisms of NEBL,as distinguished from metal-working fluid,are clarified combining with its unique molecular structure and physical properties.Furtherly,the process optimization strategy is concluded based on the synergistic relationship analysis among process variables,physicochemical properties,machining mechanisms,and performance of NEBL.Finally,the future development directions are put forward aiming at current performance limitations of NEBL,which requires improvement on preparation and jet methods respects.This paper will help scientists deeply understand effective mechanism,formulate process specifications,and find future development trend of this technology.

Cooling and lubrication techniques in grinding:A state-of-the-art review,applications,and sustainability assessment

Grinding technology is an essential manufacturing operation,in particular,when a component with a superfinishing and an ultra-resolution is yearned.Meeting the required strict quality checklist with maintaining a high level of productivity and sustainability is a substantive issue.The recent paper outlines the lubrication and cooling technologies and mediums that are used for grinding.Furthermore,it provides a basis for a critical assessment of the different lubrication/cooling techniques in terms of machining outputs,environmental impact,hygiene effect,etc.Meanwhile,the paper put light on the sustainability of different cooling/lubrication strategies.The sustainability of machining aims to get the product with the best accuracy and surface quality,minimum energy consumption,low environmental impact,reasonable economy,and minimum effect on worker’s health.The paper revealed that despite some cooling/lubrication mediums like mineral oils and semisynthetic,afford sufficient lubrication or cooling,they have a significant negative impact on the environment and public health.On the other hand,emulsions can overcome environmental problems but the economy and the energy consumption during grinding are still a matter of concern.Biodegradable and vegetable oils are considered eco-friendly oils,but they suffer from a lack of thermal stability which affects their ability of efficiently cooling.Using the cooling medium with the lowest amount can achieve the goal of the economy but it may be reflected negatively on the machinability.Furthermore,cryogenic lubrication doesn’t provide sufficient lubrication to reduce friction and hence energy consumption.The research described in the paper is such a comprehensive compilation of knowledge regarding the machinability and machining performance under different cooling and lubrication systems that it will aid the next generation of scientists in identifying current advancements as well as potential future directions of research on ecological aspects of machining for sustainability.

Nanoparticle-enhanced coolants in machining:mechanism,application,and prospects

Nanoparticle-enhanced coolants(NPECs)are increasingly used in minimum quantity lubrication(MQL)machining as a green lubricant to replace conventional cutting fluids to meet the urgent need for carbon emissions and achieve sustainable manufacturing.However,the thermophysical properties of NPEC during processing remain unclear,making it difficult to provide precise guidance and selection principles for industrial applications.Therefore,this paper reviews the action mechanism,processing properties,and future development directions of NPEC.First,the laws of influence of nano-enhanced phases and base fluids on the processing performance are revealed,and the dispersion stabilization mechanism of NPEC in the preparation process is elaborated.Then,the unique molecular structure and physical properties of NPECs are combined to elucidate their unique mechanisms of heat transfer,penetration,and antifriction effects.Furthermore,the effect of NPECs is investigated on the basis of their excellent lubricating and cooling properties by comprehensively and quantitatively evaluating the material removal characteristics during machining in turning,milling,and grinding applications.Results showed that turning of Ti‒6Al‒4V with multi-walled carbon nanotube NPECs with a volume fraction of 0.2%resulted in a 34%reduction in tool wear,an average decrease in cutting force of 28%,and a 7%decrease in surface roughness Ra,compared with the conventional flood process.Finally,research gaps and future directions for further applications of NPECs in the industry are presented.

Energy field-assisted high-speed dry milling green machining technology for difficult-to-machine metal materials

Energy field-assisted machining technology has the potential to overcome the limitations of machining difficult-to-machine metal materials,such as poor machinability,low cutting efficiency,and high energy consumption.High-speed dry milling has emerged as a typical green processing technology due to its high processing efficiency and avoidance of cutting fluids.However,the lack of necessary cooling and lubrication in high-speed dry milling makes it difficult to meet the continuous milling requirements for difficult-to-machine metal materials.The introduction of advanced energy-field-assisted green processing technology can improve the machinability of such metallic materials and achieve efficient precision manufacturing,making it a focus of academic and industrial research.In this review,the characteristics and limitations of high-speed dry milling of difficult-to-machine metal materials,including titanium alloys,nickel-based alloys,and high-strength steel,are systematically explored.The laser energy field,ultrasonic energy field,and cryogenic minimum quantity lubrication energy fields are introduced.By analyzing the effects of changing the energy field and cutting parameters on tool wear,chip morphology,cutting force,temperature,and surface quality of the workpiece during milling,the superiority of energy-field-assisted milling of difficult-to-machine metal materials is demonstrated.Finally,the shortcomings and technical challenges of energy-field-assisted milling are summarized in detail,providing feasible ideas for realizing multi-energy field collaborative green machining of difficult-to-machine metal materials in the future.