Minimum Quantity Lubrication Grinding Research Articles

Analysis of Grinding Flow Field under Minimum Quantity Lubrication Condition

The flow field around the grinding wheel prevents grinding fluid from entering the grinding area, which deteriorates machining conditions and reduces the quality of the workpiece. MQL (Minimum Quantity Lubrication) grinding uses compressed gas to improve the ability of the grinding fluid to pass through the flow field of the grinding wheel so that a small amount of the grinding fluid can meet the cooling and lubrication requirements and reduce the cost of using grinding fluid. In this study, we investigated the flow field of grinding wheels under MQL conditions and obtain the rules that influence factors such as grinding fluid flow rate, grinding wheel linear speed and compressed gas pressure affect the flow rate of grinding fluid. The simulation method was used to simulate the flow field of the grinding wheel and the trajectory of the grinding fluid droplets. The simulation results show that these factors are important ones affecting the effective flow rate of grinding fluid. Meanwhile, the experimental results verify that these factors have the same influence pattern on the effective flow rate and grinding temperature.

Atomization mechanism and machinability evaluation with electrically charged nanolubricant grinding of GH4169

Nanofluid minimum quantity lubrication (NMQL), which offers excellent economic and environmental benefits, has the greatest potential to replace traditional metal grinding with fluids. However, insufficient infiltration performance, poor atomization properties, and inferior controllability are found in pneumatic atomization minimum quantity lubrication (MQL), hindering the improvement of grinding performance. Electrostatic atomization MQL (EMQL) is expected to address the coexistence of grindability and sustainability through electrical charge empowerment. Nevertheless, studies addressing the effects and mechanisms of electrically charged nanolubricants in the grinding of nickel-based superalloys remain scarce. In this study, the atomization characteristics of EMQL are experimentally investigated, and results show that the droplet volume average diameter and diameter Rosin–Rammler distribution span of EMQL decreased by 7.1 % and 40.3 %, respectively, in comparison with those of MQL. Then, a series of grinding experiments on GH4169 with different cooling conditions are conducted. Results show that compared with those for MQL grinding, the coefficients of friction for EMQL and NMQL grinding decreased by 9.35 % and 15.62 %, the specific grinding energies decreased by 16.71 % and 29.06 %, and the values of surface roughness Sa decreased by 3.04 % and 14.33 %, respectively. The optimal combination of atomization method and medium for grinding GH4169 is EMQL and nanolubricant. Sa showed a 16.12 % decrease for the surface machined via the optimal combination compared with the surface machined via flooding. Last, to support the interpretation of the grinding outcomes, the antifriction mechanisms of electrically charged nanolubricants are analyzed in combination with the wetting, infiltration, and film-formation capabilities of droplets. The findings of this work are expected to provide experimental references for the surface integrity improvement of the nickel-based superalloy grinding process.

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

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

Application of machine learning techniques in environmentally benign surface grinding of Inconel 625

This work explores the grinding performance of Inconel 625 by comparing tangential forces and surface roughness under dry, wet, and minimum quantity lubrication (MQL) environments. Response surface methodology (RSM) and machine learning (ML) techniques establish correlations between inputs and outputs. RSM shows the quadratic regression model effectively captures experimental variability. Four ML models, namely: multilayer perceptron, KNN, and SVM with two kernels, were implemented to predict outcomes, among which KNN appeared as a better-suited model. Lower tangential forces and better ground surface quality support the suitability of MQL grinding compared with dry and wet grinding. Micro-graph investigations of the ground surfaces and chip morphology findings also upkeep the emergence of MQL grinding as a sustainable alternative for Inconel 625 grinding.

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 minimum 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 nanofluid 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 10 μm. Workpiece machined surface roughness can be decreased by over 10%, and grinding temperature can be lowered over 50 ℃ at grinding depth of 30 μm. 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 FeF2, CrF3, and BN. The fresh machined surface of workpiece is oxidized by air, producing NiO, Cr2O3 and Fe2O3. 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 nanofluids obtain excellent grinding performance.

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.

Heat Transfer Mechanism and Convective Heat Transfer Coefficient Model of Cryogenic Air Minimum Quantity Lubrication Grinding Titanium Alloy

Heat Transfer Mechanism and Convective Heat Transfer Coefficient Model of Cryogenic Air Minimum Quantity Lubrication Grinding Titanium Alloy

Synergistic impact of eco-friendly nano-lubricants on the grindability of AISI H13 tool steel: A study towards clean manufacturing

The conventional flood i.e., mineral-based cutting fluid approach was extensively utilized on the shop floor to diminish the amount of friction and power consumption while precision grinding of “difficult-to-machine” materials like hardened AISI H13 tool steel. The excessive exposure and usage of conventional fluids lead to severe environmental threats like air and water pollution, and unfavourable impacts on operator health. Therefore, sustainable manufacturing in terms of minimum quantity lubrication (MQL) grinding is major concert in modern tooling industries including technological, economical, and environmental aspects. The objective of present study is to identify the impact of six different eco-friendly nano-lubricants i.e., castor oil (CO), soybean oil (SO), castor oil-deionized water (CO + DIW) emulsion, soybean oil-deionized water (SO + DIW) emulsion, Al2O3 nanofluids (NFs): 0.5 wt%, and Al2O3 NFs: 1 wt% on grindability and surface integrity indices, energy consumption, carbon emission, and production cost while MQL grinding of AISI H13 tool steel. The lubrication mechanism and its characteristics were studied by biodegradation rate, pH and sedimentation test, thermal conductivity, viscosity, surface tension, and wettability. The grindability indices, namely, apparent friction coefficient, surface roughness (Rɑ and Rz value), bearing area (BC) ratio, surface topography, and microchip morphology were evaluated and analyzed. The results suggest that the downfeed and Al2O3 NFs have the greatest impact on technological, economical, and environmental aspects of MQL grinding. It is found that the extensive cooling and lubricating performance of Al2O3 NFs was superior to that of biodegradable emulsion, and straight vegetable oil offered the optimal results under all lubrication evaluation tests. Also, significant improvement in grindability performance was obtained with Al2O3 NFs: 1 wt% owing to strong anti-friction lubricating tribo-film, and higher boiling heat transfer through effective rolling and mending effect. The grindability enhancement rates of apparent friction coefficient, Rɑ,Rz, and BC ratio are 28.48%, 59.66%, 50.18%, and 6.25%, respectively at 32 μm downfeed as followed by SO + DIW emulsion. Furthermore, poor ground surface quality along with spherical and sharp wear tracks on microchips was indicated with SO + DIW emulsion. According to sustainable aspects, Al2O3 NFs: 1 wt% outperformed straight vegetable oil in terms of lower energy consumption (17.06 kJ), carbon emission (00468 kgCO2), and production cost (0.255 $), which were 15.10%, 26.76%, and 13.55% lower than soybean oil. It is confirmed that Al2O3 NFs is the best substitute for the straight vegetable oil and vegetable oil-deionized water emulsion for robust sustainable manufacturing of tooling components.

Study on machining performance in grinding of Ni-base single crystal superalloy DD5

The Ni-base single crystal superalloy DD5 is commonly employed in critical parts of turbine blades and turbine disks in aeronautical engines. To improve the surface machining quality, single-factor experiments were carried out to investigate the changes of grinding force, surface morphology, and chip morphology under different grinding conditions (dry, conventional flood, minimum quantity lubrication). The experiments showed that the conventional flood lubrication and minimum quantity lubrication (MQL) could enormously reduce the surface roughness, grinding force, and work-hardened layer thickness of DD5. At the depth of 5 ~ 15 μm, the DD5 subsurface microhardness decreased sharply with the increase of depth, and the microhardness under different grinding conditions was in the order of dry grinding, conventional flood, and MQL. However, at the depth of 20 ~ 150 μm, the DD5 subsurface microhardness tended to equilibrate and fluctuate around 540 HV. In addition, compared with dry grinding, the degree of chip serration was obvious in flood or MQL environment, and its chip formation frequency fluctuated less and chip formation was stable. Within the experimental parameters, the MQL grinding machining method obtained the lowest surface roughness and the highest surface quality with the lowest associated cost, which is the ideal grinding and cooling lubrication method for the Ni-base single crystal superalloy.

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

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

An analysis of frictional coefficient and surface roughness in surface grinding of SKD 11 tool steel using Minimum Quantity Lubrication (MQL) and dry techniques

This study was intended to investigate the effect of the cooling method (CM), workpiece speed (Vf), and depth of cut (doc) on frictional coefficient (FC) and surface roughness (SR) in the surface grinding of SKD 11 tool steel. CM consists of minimum quantity lubrication (MQL) and dry techniques. Power function was applied to model both FC and SR. Based on the analysis of the model, CM and VF significantly affected both responses, while doc influenced only FC. SEM photographs of the ground surfaces were also presented to compare the surface quality between MQL grinding and dry grinding.

Grinding-Hardening of Face Gears Under Minimum Quantity Lubrication with Disc Wheels

To shorten the process of face gears, the grinding-hardening effect experiment of face gears under minimum quantity lubrication(MQL) was carried out. Firstly, the grinding method of face gears was analyzed based on the envelope principle, and the control equation of grinding movement was constructed. Secondly, the distribution ratio equation of heat flux density was established, and the theoretical calculation formula of triangle heat source was derived. Thirdly, since a MATLAB calculation program was compiled, the temperature change law under MQL grinding was analyzed. In the end, the influence of grinding parameters on the grinding-hardening layer depth was analyzed. The results demonstrate that MQL grinding achieves the grinding-hardening effect.

Application of hybrid eco-friendly MQL+WCJ technique in AISI 4340 steel grinding for cleaner and greener production

Eco-efficiency solutions have been more and more proposed by researcher and industry around the world in latest years in order to become the manufacturing systems cleaner and greener. This action is related to the global warning about the generation of greenhouse gases (GHGs), like CO2, as reported by Intergovernmental Panel on Climate Change (IPCC) . One of the most hazardous issue related to environmental risk in machining process is the application of metalworking fluids (MWFs), especially in grinding process in which MWFs are pivotal to control high generation of heat and avoid workpiece surface burns and microstructural changes. The minimum quantity lubrication (MQL) was broadly reported in the literature as a potential alternative lubri-cooling technique to the conventional technique (flood - F). However, the main drawback of MQL grinding is related to high generation of clogging phenomenon produced by the chips lodged on the grinding wheel active surface (GWAS) due to the low oil volume and consequently the low lubricating and cooling action. In order to propose improvements on MQL technique, increase its efficiency and viability and develop a potential greener lubri-cooling technique, this work aims to propose and evaluate the application of hybrid HMQL + WCJ technique combined oil and water at 1:5 oil-water in the Al2O3 grinding process of AISI 4340 steel. This technique was compared to flood F and the pure PMQL + WCJ (pure oil) techniques. Both MQL techniques (hybrid and pure) employed at 30, 60 and 120 mL/h. The PMQL + WCJ technique produced the worst results irrespective of the flow rate. The HMQL + WCJ at 120 mL/h (highest flow rate) presented similar performance to the F technique in terms of surface roughness, microhardness, clogging behavior on GWAS, workpiece form deviation, grinding power, generation of CO2 during the process and acoustic emission (AE) and outperformance in terms of G ratio. This indicates the eco-efficient potential to be widely employed in manufacturing industry and mitigate the environmental impact and carbon footprint of hybrid MQL + WCJ technique.

Evaluation of a cooled wheel cleaning jet in minimum quantity lubrication grinding process

The application of the minimum quantity lubrication (MQL) technique in grinding processes is still limited due to the frequent occurrence of overheating and wheel clogging. In this context, this research evaluates a cooled wheel cleaning jet (CWCJ) under different temperatures, applied simultaneously to MQL in the cylindrical grinding of AISI 4340 quenched and tempered steel, using a CBN wheel. For comparison, tests with the MQL, MQL + WCJ, and conventional techniques were also performed. Surface roughness, microhardness, and roundness deviation of the workpieces, wheel wear, and grinding power were the assessed output parameters. The machined workpieces were evaluated by optical, confocal, and scanning electron microscopies. The MQL + WCJ outperformed MQL and MQL + WCJ in all the tested conditions. The application of the cooled wheel cleaning jet reduced by up to 79% the surface roughness, 82% the wheel wear, 76% the roundness deviation, and 37% the grinding power, regarding MQL and MQL + WCJ techniques, contributing towards a sustainable and high-quality grinding process.

Machining performance of Inconel-718 alloy under the influence of nanoparticles based minimum quantity lubrication grinding

Abstract Environmental and health problems associated with the conventional mineral-based cutting fluids has enhanced the quest of researchers to search for environment-friendly lubrication techniques. Minimum Quantity Lubrication (MQL) is the latest technique developing to reduce the use of coolants in machining. In the present work grinding of Inconel-718 (Ni-Cr alloy) has been examined under the influence of Al2O3 based Nanofluid Minimum Quantity Lubrication (NFMQL) technique using vegetable oils as the base oils in view of environmental conscious grinding. The grinding performance of Inconel-718 was evaluated in terms of surface roughness, grinding energy, cutting forces, temperature, and G-ratio. Nanofluids were prepared by adding 0.5 wt% and 1 wt% Al2O3 nanoparticles to the sunflower and rice-bran vegetable oils. From the results, it is observed that Al2O3 based nanofluid MQL with sunflower as base oil has given better results with respect to G-ratio, grinding energy, surface roughness, and coefficient of friction. Better value of surface roughness (0.5 μm) is achieved with 0.5 wt% concentration of nano-particles, whereas G-ratio (1.52), grinding energy(32.91 J/mm3) and tangential forces improved under nanofluid MQL condition with 1 wt% concentration of nanoparticles as compared to flood cooling. This might be due to the fact that while nanofluids flow through the wheel-workpiece interface, it results in the formation of a lubrication film that acts as ball bearing and reduces the sliding friction. Thus vegetable oils with the appropriate amount of Al2O3 nano-particles can give sufficient tribological properties with the environment and economic advantages.

Performance evaluation of minimum quantity lubrication technique in grinding of AISI 202 stainless steel using nano-MoS2 with vegetable-based cutting fluid

Due to environmental issue and stringent rules over defilement and contamination of the environment, the demand for renewable and biodegradable cutting fluids is increasing. In this study, an eco-friendly minimum quantity lubrication (MQL) technique using vegetable oil–based cutting fluid (rapeseed oil) by varying MQL flow rate and MQL pressure was investigated in the grinding of AISI 202 stainless steel. In addition to explore the cooling capabilities of rapeseed oil, nano-MoS2 was added to the rapeseed oil to prepare different concentrations (0.5 wt% and 1.0 wt%) of nanofluids. The main objective of this experiment is to examine the performance of different grinding environments (dry, flood, pure MQL, and nanofluid MQL) with respect to grinding characteristics, namely, grinding forces, surface morphology, surface roughness, and temperature. Experimental results revealed that NFMQL grinding with vegetable oil was performed much superior as compared with the dry, wet, and pure MQL machining. The lowest specific normal force and tangential force are observed to be 9.2 N/mm and 0.76 N/mm respectively under 1.0 wt% concentration of MoS2 nanoparticles at oil flow rate of 120 ml/h and air pressure 90 psi under MQL grinding condition, which decreased by 43% and 33%, respectively, as compared with dry conditions. Furthermore, the application of nanofluid also leads to the reduction of surface roughness and surface temperature. MQL application with MoS2 nanofluid helps in effective flushing of chip material from the grinding zone, thereby improving the lubrication and cooling capabilities during the grinding of the AISI 202 stainless steel. In summary, appropriately chosen minimum quantity lubrication parameters can enhance the lubrication and cooling properties of the oil film and improve the grinding characteristics.

Multi-objective optimization of MQL mist parameters for eco-friendly grinding

Nowadays, Minimum Quantity Lubrication (MQL) technique with eco-friendly groundnut oil is adopted in precision machining to tackle the operator health and environmental issues owing to petroleum based cutting fluid. The effectiveness of this technique depends on mixture quality of MQL mist. Hence, the objective of present work is to optimize the MQL mist parameters i.e. air pressure (P), flow rate (Q), and stand-off distance (ds) to minimize the effect of MQL based plunge grinding on hardened AISI H13 tool steel in terms of lowest grinding force, specific energy, grinding temperature, and surface roughness using grey relational analysis. Taguchi’s L16 orthogonal array was utilized for conducting the final experiments and mist parameters varied through four levels include P (2, 3, 4, and 5 bar), Q (50, 100, 150, and 200 L/h) and ds (40, 50, 60, and 70 mm). Further, experimental analysis was carried out to compare the effect of optimal and worst mist parameters on ground surface and microchip by using microhardness, scanning electron microscope, and atomic force microscopy. According to validation test, P: 4 bar, Q:200 mL/h, and ds:50 mmare optimal mist parameters for multi-response variables of MQL grinding. Effective mist quality i.e. average droplet size of 51.03 μm was obtained at nozzle angle of 12°. Excellent ground surface quality with negligible microhardness variation and no wear tract microchip were observed under optimal mist setting.

Surface morphology evaluation of multi-angle 2D ultrasonic vibration integrated with nanofluid minimum quantity lubrication grinding

Nanofluid minimum quantity lubrication (NMQL) is an emerging cleaner and sustainable technique. However, the effective immersion of nanofluids in the grinding zone in NMQL grinding limits the extensive application of this technique. Ultrasonic vibration can exert a pumping effect that injects nanofluids into the interface between the grinding wheel and workpiece. Furthermore, technique integration benefits the infiltration state transition of micro-droplets. However, evaluation of the coupling effect and surface morphology of multi-angle 2D ultrasonic vibration integrated with NMQL has rarely been performed. This study aims to address these research limitations. A kinematics model was developed, and the grain and workpiece relative motion trails in 2D ultrasonic vibration-assisted grinding (UVAG) were simulated at different resultant vibration angles (θ). The grain’s cutting characteristics were then analyzed and found to be conducive to the full infiltration of nanofluids into the grinding zone. Moreover, the surface characterization of multi-angle 2D UVAG coupled with NMQL was evaluated experimentally. Results showed that the optimal θ was achieved at 45° due to the differential cutting action of the follow-up grain. NMQL obtained a better result than flooding at the same θ. When the gain effect of the coupling techniques was reflected in surface roughness, the Ra value decreased by 19.5 % (compared with UVAG) and 39.9 % (compared with NMQL). The autocorrelation function curves presented periodic and continuous local oscillations under the grinding conditions of 2D UVAG with θ = 45° and θ = 135°.

Performance Evaluation of Inconel 718 under vegetable oils based nanofluids using Minimum Quantity Lubrication Grinding

The growing demands for high productivity in machining requires large amount of cutting fluids to control the lubrication phenomenon efficiently. The application of lubricants/coolants in machining operation has improved the efficiency of these operations, however the disposal of such coolants is hazardous to the eco-system. Hence eco friendly cutting fluids are required urgently to solve the environment problems related with traditional fluids. Minimum Quantity Lubrication (MQL) is an environmentally friendly method and efficient technique of applying cutting fluids in machining processes. In the present study Grinding of Inconel-718 has been investigated with regard to forces, surface roughness, grinding energy and G-Ratio under different cooling lubrication strategies i,e, flood, pure MQL and nanofluid MQL. For pure MQL technique sunflower and ricebran were used as base fluids, and different types of nanofluids were prepared by adding 1%, 0.5% Al2O3 nano-particles to these vegetable oils for evaluating the grinding process. From the results it is observed that sunflower has given better surface integrity and low grinding energy using pure MQL technique. Moreover, addition of Al2O3 nano-particles in the base fluid further enhanced the quality of surface, lower the grinding energy and enhanced the G-Ratio. Better surface integrity achieved under nanofluid MQL technique might be attributed to the filling and polishing effects of nano-particles along with good anti friction behaviour. Moreover nano-particles form a shearing film by penetrating into pores of workpiece surface resulted in shearing action leads to high values of G-Ratio. Hence results indicated that vegetable based nanofluids has the potential to be successfully apply at the grinding of hard materials. It appears that the proposed cooling strategy may conceivably improve the efficiency of cutting activities as far as machining quality, costs, and ecological insurance. This can enable in reduction of expensive fluid wastages which can lead to environmental friendly machining.

Investigating Minimum Quantity Lubrication in Unidirectional Cf/SiC composite grinding

The influences of minimum quantity lubrication (MQL) on the grinding performance of unidirectional carbon fibre-reinforced ceramic matrix (Cf/SiC) composites were investigated in this paper. The experimental results indicate that MQL can significantly improve surface quality and reduce grinding forces. In addition, MQL has a low cost and does not generate considerable pollution. According to the lubrication mechanism of MQL, the effects of nozzle direction, air pressure, oil flow rate and nozzle distance on the grinding performance of unidirectional Cf/SiC composites were carefully investigated in this research. Excellent surface quality and low grinding forces can be achieved when the nozzle direction, air pressure, oil flow rate and nozzle distance are 15°, 5 bar, 100 ml/h and 80 mm, respectively. The surface topographies show that smooth fibre separation, fibre breaking, fibre outcropping, fibre pullout and matrix cracks are the main failure forms of the ground surface. The histogram reflects that the proportion of fibre pullout is the highest, whereas that of fibre outcropping is lowest. In the MQL grinding process, a large amount of heat is removed by water vapour, which can significantly reduce the grinding temperature. Meanwhile, effective oil films form in the contact areas between the grits and the material surface. The above factors are advantageous for improving the grinding performance of unidirectional Cf/SiC composites. The objective of this research was to investigate the influences of MQL for unidirectional Cf/SiC composites, validate these interpretations with experimental results and provide reasonable recommendations for guaranteeing the machining accuracy of Cf/SiC composites.