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.

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.

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.

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.

MQL加工技术的研究与进展

最小量润滑(Minimum Quantity Lubrication,简称MQL)是一种绿色环保切削加工技术。本文介绍了MQL加工的特点,归纳和总结了其应用研究成果,指出了MQL加工中的关键问题和尚待解决的主要问题,并探讨了其今后的发展趋势。

MQL参数对40Cr磨削强化层表面质量影响的试验研究

为了改善磨削强化层的表面质量,将微量润滑(简称MQL)应用于磨削强化工艺。采用MQL技术对40Cr钢进行磨削强化试验,研究了润滑冷却工艺,如磨削液供给方式、MQL喷射流量、空气压力等对磨削强化层深度、表面显微硬度和表面粗糙度等的影响。结果表明:在湿磨条件下,工件表面没有产生强化层;在MQL磨削条件下,获得的强化层深度略低于干磨,但表面显微硬度较干磨有所提高,且MQL下工件表面的粗糙度低于干磨;在MQL磨削强化中,增加MQL喷射流量和空气压力均有利于提高强化层的表面硬度和降低表面粗糙度。因此,MQL磨削强化能提高工件表面的质量,改善零部件的使用性能。

MQL加工的微量冷却润滑系统

针对大量浇注式传统切削冷却润滑存在的主要问题,提出并构建了由供液系统、切削液和雾液回收装置所组成的适用于MQL加工的微量切削液冷却润滑系统,并阐述了微量冷却润滑系统对机床、工具系统和刀具兼容性的要求,为制造微量切削液冷却润滑系统和实施MQL加工工艺提供了理论和工程依据。

球形纳米颗粒在镍基合金纳米流体微量润滑磨削界面摩擦学机制的分子动力学研究

以1-丁基-3-甲基咪唑四氟硼酸盐([BMIM]BF 4离子液)作为纳米流体基液,以氧化铝和铜纳米颗粒分别作为高硬度类和低硬度类球形纳米颗粒的代表,用分子动力学模拟方法研究了球形纳米颗粒在镍基合金纳米流体微量润滑磨削界面减摩抗磨的摩擦学机理,并进一步揭示了纳米流体在砂轮磨粒/工件磨削界面润滑成膜的摩擦学机制。研究结果表明,在镍基合金纳米流体微量润滑磨削加工中,砂轮磨粒/工件磨削界面形成了边界润滑膜。由于铜纳米颗粒硬度远低于砂轮磨粒及镍基合金工件,会在磨粒/工件界面出现压缩、剪切、铺展和分离等一系列摩擦学行为,并形成一层固体润滑膜,这层固体膜通过减小磨粒工件之间的直接接触面积来减小切向磨削力,相较于微量润滑工况可使切向磨削力减小4.6%。由于氧化铝纳米颗粒硬度高于镍基合金工件,故在磨削过程中仍能保持原本的球形纳米结构,会在磨粒/工件界面出现滑移、滚动和抛光三种摩擦学行为,抛光划痕可增大离子液体的浸润面积,并减小磨粒工件之间的直接接触面积,“类滚珠”的滚动行为可将磨粒工件之间的滑动摩擦转变为滚动摩擦,从而使切向磨削力较微量润滑工况减小6.6%。

基于石墨烯强化MQL的GH4169合金铣削表面质量研究

为了改善GH4169合金铣削加工的表面质量,基于微量润滑(MQL)技术,将石墨烯纳米粒子添加到植物油基切削液中以强化其冷却润滑性能.结合正交试验方案,采用极差分析和方差分析方法,研究了M QL参数(石墨烯质量分数、切削液流量、气体压强)对表面粗糙度的影响规律,并得到了最优的参数组合.研究结果表明,石墨烯质量分数对GH4169合金铣削加工表面粗糙度的影响是最显著的,其次是气体压强,最后是切削液流量;同时,最优的表面粗糙度为0.406μm,最优参数组合为石墨烯质量分数0.1%,切削液流量60 mL/h,气体压强0.6 M Pa;适当的M QL参数可以显著地改善切削区的冷却润滑状态,从而改善表面质量,降低表面粗糙度.

基于流体动力学仿真的微量润滑喷嘴参数优化

微量润滑(MQL)切削技术在切削加工中获得了良好的加工效果,其中喷嘴参数对微量润滑性能有着重要影响。为改善和优化微量润滑性能,采用正交试验法和ANSYS Fluent软件对气相窄流区宽度、锥度、输出管长度、气相窄流区长度、输出孔径、流量等6个因素的影响进行了流体动力学的数值仿真研究和统计分析。结果表明,在不同评价标准下,6个影响因素的主次顺序不同;影响综合指数的最重要参数为距离喷嘴0.1 m处的喷射截面分散程度,影响综合指数的优先顺序为:距离喷嘴0.1 m处的喷射截面分散程度>距离喷嘴0.2 m处的喷射截面分散程度>离喷嘴0.3 m处的喷射截面分散程度>喷射方向衰减率>离喷嘴0.05 m处的喷射绝对速度;喷嘴参数的最优组合为:输出孔径1.5 mm、输出管长度0.5 mm、锥度45°、气相窄流区宽度0.2 mm、气相窄流区长度0.5 mm、流量40 L/min。

不同MQL安置方式对高速精密车削的影响研究

为比较不同的MQL安置方式对高速精密车削加工的影响,使用德国某公司的超精密机床SB-CNC对轴承钢GCr15分别进行干式、切削液外置供给式MQL以及切削液内置供给式MQL切削试验。通过Kistler加速度传感器和压电式力传感器分别对车刀在加工过程中的径向振动信号和刀尖的三向切削力信号进行采集,并对采集到的信号做时域和频域分析。结果显示,两种MQL润滑方式都对减小切削力和加工中的低频颤振有所抑制,其中,内置式MQL在抑制颤振方面比外置式MQL更有优势,二者在减小切削力能力方面则未见明显区别。

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.

低温微量超声雾化声学系统

针对低温微量超声雾化声学系统中的关键部件单波长超声雾化喷嘴进行研究。首先基于等效电路原理和传输矩阵法分别建立了带中心孔换能器和带中心孔复合变幅杆的频率方程,并应用数学分析软件获得了准确的数值解,实现了超声雾化喷嘴的全谐振。然后,对其进行有限元动力学分析和振动特性测试,结果表明二者相对于设计频率25 kHz的偏差率在0.6%以内,且空载超声振幅达13.5μm。之后,应用流体仿真分析软件对砂轮-工件磨削区进行流场特性分析,结果表明低温微量超声雾化声学系统可以解决磨削区涡流现象的产生。最后,通过对该系统使用前后两种润滑方式的磨削结果进行测试发现:低温微量超声雾化润滑不仅切削液使用量少,而且可以避免工件表面出现烧伤和硬度降低。

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.

准干式切削微量润滑装置研究进展

准干式微量润滑切削技术是我国绿色制造-可持续发展战略的重要内容,而微量润滑装置是该技术的核心。针对外部雾化型和内部雾化型微量润滑技术,系统分析了两种技术对应的外置式微量润滑装置和内置式微量润滑装置技术原理和应用特点,分析了不同类型微量润滑装置配套的油泵、喷嘴以及专用内冷主轴和内冷刀柄等关键部件研究进展和应用形式,并结合微量润滑技术在实际应用中存在的冷却润滑性不足问题,进一步介绍了静电微量润滑、油水复合微量润滑以及纳米流体微量润滑等复合增效型微量润滑技术原理和装置特点,总结分析了系列微量润滑装置应用特点并展望了微量润滑装置发展方向,为微量润滑装置的进一步升级优化和工程应用提供参考。

最小量润滑下搅拌摩擦焊接AA2014合金的组织与力学性能

搅拌摩擦焊(FSW)的余热溶解析出相降低了沉淀强化AA2014合金的接头质量。本研究采用最小量润滑(MQL)技术来散热,将采用两步法制备的石墨烯纳米流体作为冷却剂,用光学显微镜、扫描电镜、透射电镜、X射线衍射和差示扫描量热法研究晶粒结构和析出相的发展。结果表明,在不同转速和焊接速度组合下,不同的热循环对析出相的转变不同,从而对焊缝性能产生调节作用,成功消除无沉淀析出带的形成。采用n-MQL技术产生了稳定的θ相,从而使焊接接头有更高的焊接性能。在1200 r/min的转速和72 mm/min的焊接速度下,建立了具有优异性能的工艺窗口。

低温微量润滑技术在航空金属材料铣削中的应用研究

低温微量润滑(CMQL)作为节能环保的绿色加工技术,在航空航天等高端制造业中逐渐有替代传统切削液的趋势。针对航空制造业中常用的铝合金、钛合金和钢三种材料设计正交试验,并验证设定温度、微量润滑油量、进给速度对切削温度的影响。试验数据分析表明,应用CMQL技术可有效降低切削温度;在铝合金与钢的铣削中设定温度对切削温度的影响最大;在钛合金铣削中,微量润滑油量对切削温度的影响最大。

低温微量润滑技术及其作用机理研究

随着高效绿色切削技术的发展,低温微量润滑技术应运而生。它是在微量润滑的基础上结合低温冷风发展而来。文中简要介绍了低温微量润滑技术及其切削性能。低温微量润滑技术体现了良好的切削性能,大大提高了刀具耐用度,为以后更好的应用奠定了坚实的基础。同时,文中还阐述和分析了低温微量润滑的渗透机理,以及冷却和润滑作用机理。通过理论分析,低温微量润滑技术能够更有效地实现对切削加工区的冷却和润滑。并通过试验证明,低温冷风结合微量润滑技术能够有效地降低切削温度和切削力,改善切削加工性能。