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.

Vegetable Oil-Based Nanolubricants in Machining:From Physicochemical Properties to Application

Cutting fluid is crucial in ensuring surface quality and machining accuracy during machining.However,traditional mineral oil-based cutting fluids no longer meet modern machining’s health and environmental protection require-ments.As a renewable,pollution-free alternative with excellent processing characteristics,vegetable oil has become an inevitable replacement.However,vegetable oil lacks oxidation stability,extreme pressure,and antiwear proper-ties,which are essential for machining requirements.The physicochemical characteristics of vegetable oils and the improved methods’application mechanism are not fully understood.This study aims to investigate the effects of viscosity,surface tension,and molecular structure of vegetable oil on cooling and lubricating properties.The mechanisms of autoxidation and high-temperature oxidation based on the molecular structure of vegetable oil are also discussed.The study further investigates the application mechanism and performance of chemical modification and antioxidant additives.The study shows that the propionic ester of methyl hydroxy-oleate obtained by epoxidation has an initial oxidation temperature of 175℃.The application mechanism and extreme pressure performance of conventional extreme pressure additives and nanoparticle additives were also investigated to solve the problem of insufficient oxidation resistance and extreme pressure performance of nanobiological lubricants.Finally,the study discusses the future prospects of vegetable oil for chemical modification and nanoparticle addition.The study provides theoretical guidance and technical support for the industrial application and scientific research of vegetable oil in the field of lubrication and cooling.It is expected to promote sustainable development in the manufacturing industry.

Material Removal Mechanism and Force Modeling in Ultrasonic Vibration-Assisted Micro-Grinding Biological Bone

Micro-grinding with a spherical grinding head has been deemed an indispensable method in high-risk surgeries, such as neurosurgery and spine surgery, where bone grinding has long been plagued by the technical bottleneck of mechanical stress-induced crack damage. In response to this challenge, the ultrasound-assisted biological bone micro-grinding novel process with a spherical grinding head has been proposed by researchers. Force modeling is a prerequisite for process parameter determination in orthopedic surgery, and the difculty in establishing and accurately predicting bone micro-grinding force prediction models is due to the geometric distribution of abrasive grains and the dynamic changes in geometry and kinematics during the cutting process. In addressing these critical needs and technical problems, the shape and protrusion heights of the wear particle of the spherical grinding head were frst studied, and the gradual rule of the contact arc length under the action of high-speed rotating ultrasonic vibration was proposed. Second, the mathematical model of the maximum thickness of undeformed chips under ultrasonic vibration of the spherical grinding head was established. Results showed that ultrasonic vibration can reduce the maximum thickness of undeformed chips and increase the range of ductile and bone meal removals, revealing the mechanism of reducing grinding force. Further, the dynamic grinding behavior of diferent layers of abrasive particles under diferent instantaneous interaction states was studied. Finally, a prediction model of micro-grinding force was established in accordance with the relationship between grinding force and cutting depth, revealing the mechanism of micro-grinding force transfer under ultrasonic vibration. The theoretical model’s average deviations are 10.37% in x-axis direction, 6.85% in y-axis direction, and 7.81% in z-axis direction compared with the experimental results. This study provides theoretical guidance and technical support for clinical bone micro-grinding.

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.

Biological Stability of Water-Based Cutting Fluids:Progress and Application

The application of cutting fluid in the field of engineering manufacturing has a history of hundreds of years,and it plays a vital role in the processing efficiency and surface quality of parts.Among them,water-based cutting fluid accounts for more than 90%of the consumption of cutting fluid.However,long-term recycling of water-based cutting fluid could easily cause deterioration,and the breeding of bacteria could cause the cutting fluid to fail,increase manufacturing costs,and even endanger the health of workers.Traditional bactericides could improve the biological stability of cutting fluids,but they are toxic to the environment and do not conform to the development trend of low-carbon manufacturing.Low-carbon manufacturing is inevitable and the direction of sustainable manufacturing.The use of nanomaterials,transition metal complexes,and physical sterilization methods on the bacterial cell membrane and genetic material could effectively solve this problem.In this article,the mechanism of action of additives and microbial metabolites was first analyzed.Then,the denaturation mechanism of traditional bactericides on the target protein and the effect of sterilization efficiency were summarized.Further,the mechanism of nanomaterials disrupting cell membrane potential was discussed.The effects of lipophilicity and the atomic number of transition metal complexes on cell membrane penetration were also summarized,and the effects of ultraviolet rays and ozone on the destruction of bacterial genetic material were reviewed.In other words,the bactericidal performance,hazard,degradability,and economics of various sterilization methods were comprehensively evaluated,and the potential development direction of improving the biological stability of cutting fluid was proposed.

Force model in electrostatic atomization minimum quantity lubrication milling GH4169 and performance evaluation

The nickel-based high-temperature alloy GH4169 is the material of choice for manufacturing critical components in aeroengines,and electrostatic atomization minimum quantity lubrication(EMQL)milling represents a fundamental machining process for GH4169.However,the effects of electric field parameters,jet parameters,nozzle position,and milling parameters on milling performance remain unclear,which constrains the broad application of EMQL in aerospace manufacturing.This study evaluated the milling performance of EMQL on nickel-based alloys using soybean oil as the lubrication medium.Results revealed that compared with conventional pneumatic atomization MQL milling,EMQL reduced the milling force by 15.2%-15.9%,lowered the surface roughness by 30.9%-54.2%,decreased the average roughness spacing by 47.4%-58.3%,and decreased the coefficient of friction and the specific energy of cutting by 55%and 19.6%,respectively.Subsequent optimization experiments using orthogonal arrays demonstrated that air pressure most significantly affected the milling force and specific energy of cutting,with a contribution rate of 22%,whereas voltage had the greatest effect on workpiece surface roughness,contributing 36.71%.Considering the workpiece surface morphology and the potential impact of droplet drift on environmental and health safety,the optimal parameter combination identified were a flow rate of 80 mL/h,an air pressure of 0.1 MPa,a voltage of 30 kV,a nozzle incidence angle of 35°,an elevation angle of 30°,and a target distance of 40 mm.This research aimed to provide technical insights for improving the surface integrity of aerospace materials that are difficult to machine during cutting operations.

Analysis of grinding mechanics and improved grinding force model based on randomized grain geometric characteristics

Too high grinding force will lead to a large increase in specific grinding energy, resulting in high temperature in grinding zone, especially for the aerospace difficult cutting metal materials,seriously affecting the surface quality and accuracy. At present, the theoretical models of grinding force are mostly based on the assumption of uniform or simplified morphological characteristics of grains, which is inconsistent with the actual grains. Especially for non-engineering grinding wheel,most geometric characteristics of grains are ignored, resulting in the calculation accuracy that cannot guide practical production. Based on this, an improved grinding force model based on random grain geometric characteristics is proposed in this paper. Firstly, the surface topography model of CBN grinding wheel is established, and the effective grain determination mechanism in grinding zone is revealed. Based on the known grinding force model and mechanical behavior of interaction between grains and workpiece in different stages, the concept of grain effective action area is proposed. The variation mechanism of effective action area under the influence of grain geometric and spatial characteristics is deeply analyzed, and the calculation method under random combination of five influencing parameters is obtained. The numerical simulation is carried out to reveal the dynamic variation process of grinding force in grinding zone. In order to verify the theoretical model, the experiments of dry grinding Ti-6Al-4 V are designed. The experimental results show that under different machining parameters, the results of numerical calculation and experimental measurement are in good agreement, and the minimum error value is only 2.1 %, which indicates that the calculation accuracy of grinding force model meets the requirements and is feasible. This study will provide a theoretical basis for optimizing the wheel structure, effectively controlling the grinding force range, adjusting the grinding zone temperature and improving the workpiece machining quality in the industrial grinding process.

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.

Fiber-reinforced composites in milling and grinding:machining bottlenecks and advanced strategies

Fiber-reinforced composites have become the preferred material in the fields of aviation and aerospace because of their high-strength performance in unit weight.The composite components are manufactured by near netshape and only require finishing operations to achieve final dimensional and assembly tolerances.Milling and grinding arise as the preferred choices because of their precision processing.Nevertheless,given their laminated,anisotropic,and heterogeneous nature,these materials are considered difficult-to-machine.As undesirable results and challenging breakthroughs,the surface damage and integrity of these materials is a research hotspot with important engineering significance.This review summarizes an up-to-date progress of the damage formation mechanisms and suppression strategies in milling and grinding for the fiber-reinforced composites reported in the literature.First,the formation mechanisms of milling damage,including delamination,burr,and tear,are analyzed.Second,the grinding mechanisms,covering material removal mechanism,thermal mechanical behavior,surface integrity,and damage,are discussed.Third,suppression strategies are reviewed systematically from the aspects of advanced cutting tools and technologies,including ultrasonic vibration-assisted machining,cryogenic cooling,minimum quantity lubrication(MQL),and tool optimization design.Ultrasonic vibration shows the greatest advantage of restraining machining force,which can be reduced by approximately 60%compared with conventional machining.Cryogenic cooling is the most effective method to reduce temperature with a maximum reduction of approximately 60%.MQL shows its advantages in terms of reducing friction coefficient,force,temperature,and tool wear.Finally,research gaps and future exploration directions are prospected,giving researchers opportunity to deepen specific aspects and explore new area for achieving high precision surface machining of fiber-reinforced composites.