Dry Lubrication Conditions Research Articles

Optimization Of Process Parameters In Turning 817M40T Steel At Minimum Quantity Lubrication (MQL) Condition

This research conducts optimization of cutting parameters on surface roughness during turning of 817M40T steel under dry and minimum quantity lubrication (MQL) conditions. The cutting parameters such as spindle speed, feed rate and depth of cut were the parameters taken as input variables for the investigation of the surface roughness quality. The experimental design adopted in this work was a three-factors-three-levels of L9 Orthogonal Array of Taguchi Robust Design Technique. Fifty four samples were experimented in a CNC Turning in dry and MQL environment and surface roughness measured using profilometer instrument. The optimal surface roughness value for MQL condition was found to be 1.9853μm. The result of ANOVA has the spindle speed contributing 71.5 %, followed by feed rate 14.10% and depth of cut has least effect of 7.80%. In dry condition, the result of ANOVA has spindle speed with 55.78% contribution followed by feed rate of 35.7% while depth of cut has least effect of 5.52%. In dry condition, the optimum value of surface roughness is 2.7096μm. MQL cutting condition was found to be better and more reliable because it is environmentally friendly and gives better surface finish. With the obtained optimum input parameters for surface roughness, production machining operations will be enhanced

Experimental study of the tribological characteristics of a honed cylinder liner during the running-in process

Abstract. The tribological properties of the cylinder liner are of great significance in reducing energy loss from an internal combustion engine's system. In order to improve the antiwear performance of the cylinder liner at top dead center (TDC), the friction and wear of the honed cylinder liner during the running-in process are investigated. Using a UMT TriboLab multifunction friction wear tester, the coefficients of friction (COFs) are analyzed under different lubrication conditions and loads, and the surface roughness and profile of the cylinder liner are obtained using a three-dimensional (3D) laser scanning confocal microscope (LSCM). The COF, roughness and surface profile are compared in order to investigate the variation in tribology parameters under different operating conditions. To monitor the COF in real time, it is predicted using the polynomial fitting method. It is shown that the COF decreases with an increase in the lubrication oil and load and that the surface profile more easily becomes smooth under dry (lubrication) conditions; this can effectively shorten the operation time during the running-in process. The polynomial fitting method can achieve an assessment of the COF with a very small standard error.

Microstructure- and cooling/lubrication environment-dependent machining responses in side milling of direct metal laser-sintered and rolled Ti6Al4V alloys

Ti6Al4V manufactured by direct metal laser sintering (DMLS) is a difficult-to-cut material and has a different microstructure to conventional Ti6Al4V. Therefore, this work aims to investigate the influence of microstructure characteristic and sustainable cooling/lubrication method on machining responses of Ti6Al4V. Side milling tests were performed under dry and supercritical CO2-based minimum quantity lubrication (scCO2-MQL) conditions. Experimental materials were DMLS-produced Ti6Al4V and conventional rolled one. Milling force, subsurface microstructure evolution, crystallographic texture, and residual stress were evaluated. For DMLS Ti6Al4V, subsurface plastic deformation depth increased with increasing cutting speed vc. Only under the most drastic condition (highest vc = 180 m/min, dry milling), a white layer with grain refinement down to 0.4 μm was formed, which resulted from α→β phase transformation and twinning-induced dynamic recrystallization. The activated twinning within the grain refinement layer was 101¯21¯011 and 101¯11¯012 twinning. For conventional Ti6Al4V, in contrast, no subsurface microstructure evolutions were identified after milling. Milled surface of rolled Ti6Al4V exhibited residual tensile stresses while DMLS Ti6Al4V exhibited residual compressive stresses. Milling force of rolled alloy was 15 % higher than DMLS-produced one. The different cutting responses of the two alloys are attributed to the fact that rolled Ti6Al4V has fine-grained microstructures while DMLS alloy has coarse-grained microstructures. The proposed scCO2-MQL method can improve machinability and surface integrity, and suppress the activation of high order twinning of DMLS Ti6Al4V. This study’s findings may be useful in developing finite element or analytical models for predicting the microstructural variations of DMLS Ti6Al4V during cutting.

Assessment of frictional performance of deep drawing quality steel sheets used in automotive industry

This article presents the results of tribological tests of three grades of deep-drawing quality steel sheets used in the automotive industry. The frictional properties of the sheets were anaysed using a strip drawing test. Friction tests were performed under dry friction and lubrication conditions using machine oil L-AN 46. Additionally, friction tests of pre-strained sheets were also carried out. Cylindrical countersamples with different surface roughness were used. Relationship between the surface roughness, pressure force, lubrication conditions and the value of the friction coefficient were evaluated. It was found that increasing the roughness of the countersamples increased the value of the friction coefficient in both friction conditions analysed. The greater the pressure force, the lower efficiency of lubrication. The effectiveness of reducing the value of the friction coefficient ranged from 20-30% and depended on the pressure force, roughness of the countersamples and the degree of specimen pre-straining.

Tribological behaviour of Ti-6Al-4V titanium alloy sheets measured by a strip drawing test

This article presents the results of friction testing of Ti-6Al-4V titanium alloy 0.5 mm thickness sheets. The strip drawing test is the basic test for assessing the frictional properties of sheets intended for the sheet forming process. The device was mounted on a typical uniaxial tensile testing machine. The tests were carried out under dry friction and lubrication conditions with the use of a wide spectrum of oil types: gear oil 75W-85, engine oil 10W-40, machine oil L-AN 46 and hydraulic oil L-HL 46. Moreover, the use of biodegradable vegetable lubrication is also examined, i.e., rape-seed and palm oils, with the addition of boric acid with a concentration of 5% w/w. Experimental studies have shown that 10W-40 engine oil was the most effective in reducing the coefficient of friction in the pressure range of 10.7 MPa-16.3 MPa (typical pressure range for the deep drawing process).

Tribological properties of graphene oxide and polyethylene glycol composites under dry friction and oil lubrication conditions

AbstractIn the low speed and heavy load of large machinery rotation or sliding parts, the application of copper base ink plate is very extensive. In this study, the graphene oxide‐polyethylene glycol (GO‐PEG) thin films were prepared on the surface of steel plates by gradient heating, and we simulated the friction and wear state of the solid material when it was brought to the metal surface. And the Fourier transform infrared spectroscopy, X‐ray diffraction, X‐ray energy spectrum analysis, Raman spectroscopy (Raman), and thermogravimetric analysis were used to characterize the structure and properties. The tribological results show that the GO‐PEG composite film prepared by gradient temperature rise method has good lubrication effect. The addition of GO greatly enhances the mechanical properties of the composite films. Compared with the single GO film, the friction coefficient is reduced by 50% and the wear rate is reduced by 85%. The unique characteristics of PEG solved the accumulation phenomenon caused by the strong van der Waals force between GO, then the PEG adhered on GO surfaces caused good lubrication effect. At the same time, the composite film has a broad application prospect in the working environment with little oil and no oil.

Corrosion Resistance and Surface Bioactivity of Ti6Al4V Alloy after Finish Turning under Ecological Cutting Conditions

The influence of cooling conditions and surface topography after finish turning of Ti6Al4V titanium alloy on corrosion resistance and surface bioactivity was analyzed. The samples were machined under dry and minimum quantity lubrication (MQL) conditions to obtain different surface roughness. The surface topographies of the processed samples were assessed and measured using an optical profilometer. The produced samples were subjected to electrochemical impedance spectroscopy (EIS) and corrosion potential tests (Ecorr) in the presence of simulated body fluid (SBF). The surface bioactivity of the samples was assessed on the basis of images from scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) analysis. The inspection of the surfaces of samples after turning under dry and MQL conditions revealed unevenly distributed precipitation of hydroxyapatite compounds (Ca/P) with a molar ratio in the range of 1.73–1.97. Regardless of the cutting conditions and surface roughness, the highest values of Ecorr ~0 mV were recorded on day 7 of immersion in the SBF solution. The impedance characteristics showed that, compared to the MQL conditions, surfaces machined under dry conditions were characterized by greater resistance and the presence of a passive layer on the processed surface. The main novelty of the paper is the study of the effect of ecological machining conditions, namely, dry and MQL cutting on the corrosion resistance and surface bioactivity of Ti6Al4V titanium alloy after finish turning. The obtained research results have practical significance. They can be used by engineers during the development of technological processes for medical devices made of Ti6Al4V alloy to obtain favorable functional properties of these devices.

Microstructure, interface, and nanostructured surface modifications to improve mechanical and tribological performance of electrodeposited Ni-W-TaC composite coating

In this study, the influence of codeposited TaC particles on the microstructure of NiW matrix was investigated. The microstructure was significantly influenced, and a thick amorphous interface between TaC and the matrix phase was observed. Similarly, further advanced surface modification treatment, ultrasonic nanocrystal surface modification (UNSM) technique, was applied to the Ni-W-TaC composite coating to investigate surface characteristics, mechanical, and tribological performance. Different characterization tools such as XRD, HRTEM, SEM, EDS, and surface roughness tests have been utilized to examine the microstructure, interface, and surface-related properties of NiW, Ni-W-TaC, and UNSM Ni-W-TaC composite coatings. The synergetic strength of TaC incorporation in the microstructure and nanostructured surface modification distinctly improved the microhardness (≈ 880 HV), with small indentation, of UNSM Ni-W-TaC coating. As a result, a reduction in the coefficient of friction (COF) (μ ≈ 0.1) under a 15 N load was obtained in UNSM Ni-W-TaC coating against a steel ball under dry lubrication conditions.

Study on hardness and wear resistance of shot peened AA7075-T6 aluminum alloy

AA7075-T6 aluminum alloy samples were shot peened at various shot peening pressures in the range of 10–70 psi to study their mechanical and tribological properties under dry and mineral oil lubrication conditions. The surface roughness of the shot peened AA7075-T6 samples apparently increased with increased shot peening pressure. The best bearing surface was obtained when the shot peening process was carried out at the highest shot peening pressure of 70 psi. It was found that the increased shot peening pressure increased the hardness and decreased the wear of the shot peened samples. The shot peened samples tested under the mineral oil lubrication condition also had lower wear for higher shot peening pressures due to the combined effects of their higher surface wear resistance and better bearing surfaces. The results clearly showed that using the mineral oil lubricant during sliding apparently decreased the wear of the shot peened samples as a result of the lubricating effect of the lubricant. It could be deduced that the tribological properties of the shot peened AA7075-T6 samples under the dry and lubrication conditions were affected by the shot peening pressure.

Tribological properties of superhydrophobic aluminium surfaces with extremely high and very low water adhesion

AbstractThe water adhesion of a superhydrophobic surface depends on its surface microstructure and chemical composition, which in turn affects its tribological properties. In this paper, a simple and environmentally friendly method was employed to fabricate superhydrophobic aluminium surfaces with different water adhesion. The results confirmed that the superhydrophobic aluminium surfaces with different water adhesion had different tribological properties under dry friction and water lubrication conditions. The sticky superhydrophobic sample with high adhesion had better wear resistance and lower friction coefficient than the slippery superhydrophobic one with very low adhesion. In addition, the related tribological properties were analyzed. This study is helpful to understand the tribological properties of superhydrophobic surfaces with different water adhesion more clearly, which is of great significance for their practical application.

Self-lubricating behavior of VN coating catalyzed by solute Ag atom under dry friction and oil lubrication

The development of hard-yet-tough ceramic coatings with self-lubricating behavior is an urgent technological requirement to reduce mechanical friction losses and energy consumption. However, traditional ceramics possessing the limited self-lubricating ability and poor toughness have limited their practical applications. To tackle the above-mentioned problems, we modified ceramic material vanadium nitride (VN) to prepare the catalytically active V-Ag-N solid solution coating by magnetron sputtering and realized high hardness, high toughness, and excellent self-lubricating performance under dry friction and oil lubrication conditions. Through detailed experimental investigations, we explain the enhanced mechanism of both hardness and toughness because of solute Ag; moreover, the solute Ag can trigger the appearance of lubricating silver vanadate phase in dry friction and result in a low coefficient of friction. Besides, it was confirmed that the solute Ag atom would induce effectively catalytic ability for in situ formation of self-lubricating onion-like-carbon structures (OLCs) scrolls from base oil at the sliding interface. The novel strategy would be to open a window for more efficiently catalyzing the in situ formation of silver vanadate and OLCs scrolls activated by solute Ag atoms and more significantly improving the hardness and toughness, thereby further improving self-lubricating behavior under dry friction and oil lubrication conditions.

Utilization of waste vegetable oil methyl esters as lubricant oil

Increasing environmental awareness and threats to the environment have made the recycling of biomass products necessary. The goal of this paper is to study the tribological properties of fatty acid methyl esters derived from waste frying oils under different lubrication conditions. For this purpose, the performance of candidate fatty acid methyl esters was compared with a mineral base oil. For the determination of tribological properties, a pin-on-disc wear tester was used. The experiments were carried out in three replications at different loads (5, 10, and 15 N) and different sliding speeds (100, 300, and 600 r/min) and a 1000 m sliding distance under dry, boundary-mixed, and fluid lubrication conditions. After the wear amount of the test specimens was determined by the mass loss method, their Archard wear indexes were calculated. Scanning electron microscopy surface images were used for visual analysis and energy-dispersive X-ray spectroscopy images for chemical analysis. The surface contact angles and surface tensions of the lubricant test specimens were also measured experimentally. In all experimental results, it has been found that the tribological properties of used frying oil fatty acid methyl esters such as friction, wear, and surface adhesion are generally better than the base oil under all lubrication conditions. Fatty acid methyl esters is a biodegradable, recycling, and environmentally friendly product and can be confirmed as a lubricant and/or an oil additive candidate.

Micromanufacturing Technology and its Practice

In order to make micro composite drills (Fig. 1), cemented tungsten carbide (WC-10Co) and high strength (AISI 4340) steel were successfully bonded by hot compaction diffusion bonding at a low temperature. The effects of holding time, pressure and temperature on microstructure and mechanical properties of the sintered carbides and bonding strengths of the bimetallic composites were examined, and a transitional layer was found at the interface as a result of elemental inter-diffusion. The optimal bonding parameters were determined to achieve the maximum bonding strength of 226 MPa of the WC-10Co/AISI 4340 steel joints, which is helpful in producing micro composite drills. Microforming is introduced to produce lighter and more energy effective products. In this study, Magnesium-Lithium (Mg-Li) alloy, new material in microscale, was chosen to superior formed micro-cup due to its ultralight weight with outstanding ductility. The dry and oil lubrication conditions were chosen as benchmarks to investigate effects of a novel oil-based nanoparticle lubricant in micro deep drawing (MDD) process of Mg-Li alloy. Finite Element (FE) modelling was conducted and the simulation results of the drawing force were in a good agreement with the experimental results. The formed cup quality with consideration on the surface roughness has been extensively evaluated and the results illustrated the quality improvement was substantial.

Grinding characteristics during ultrasonic vibration assisted grinding of alumina ceramic in selected dry and MQL conditions

Ultrasonic vibration assisted grinding (UAG) has proven to lower the forces and improve the ground surface quality while shaping difficult to grind materials such as ceramics. A systematic study of UAG of alumina ceramic using a metal bonded diamond grinding wheel has been performed here. Taguchi’s L18 array based experimentation has been performed to study the effect of UAG parameters. During UAG, the vibration amplitudes of 6 and 12 microns have been used and the frequency has been kept at 20 kHz. From these experiments, optimum parameters for UAG have been identified using Grey relational analysis. Mathematical models generated using regression analysis have been found to correlate the experimental data with good accuracy. A comparison of the grinding forces and roughness of the surfaces generated in dry and minimum quantity lubrication (MQL) conditions in both conventional grinding and optimal condition in UAG has been performed to identify the beneficial effects of providing vibration to the workpiece. The surface quality has been evaluated using 3D roughness data, 3D plots and SEM images of the ground surface. By examining nature of the ground surface and kurtosis (Sku) values of the surface profile, it has been concluded that UAG reduces brittle fracture and facilitates material removal by ductile mode for alumina. The desired condition of least machining forces and highest surface quality has been achieved during the combination of UAG and MQL.

Friction and Wear Characterization of Spark Plasma Sintered Hybrid Aluminum Composite Under Different Sliding Conditions

Abstract Friction and wear behaviors of hybrid aluminum matrix self-lubricating nanocomposite, containing varying amount of nano-aluminum oxide (Al2O3) and graphene nanoplatelet (GNP) particles were investigated under dry and boundary lubrication sliding conditions. All the specimens were prepared by ultrasonic probe mixing followed by high-energy mechanical ball milling and spark plasma sintering fabrication route. The objective of this present study is to determine the tribological behavior of GNP as nanoreinforcement under dry and wet lubricating conditions. The wear test was carried out at room temperature on a ball-on-disc reciprocating tribometer with a contact load of 5 N, a frequency of 30 Hz, a stroke of 2 mm, and a sliding distance of 120 m. The chromium-plated chrome steel ball is used as the counter body for tribo-testing. From the results, it has been observed that GNP, as the solid lubricant reinforcement, reduces the friction by 25.33% and 68.14% under dry and wet lubricating conditions, respectively, for the hybrid composite. Reduction in wear volume by 91.15% and 90.50% is observed under dry and wet lubricating conditions, respectively, for the hybrid composite in comparison to the base eutectic Al–Si alloy. The reduction in the coefficient of friction and wear volume for the hybrid composite is attributed to the multilayer two-dimensional GNP nanoparticles that cause easy shearing by forming a conformal protective film layer on the sliding interface. Ultra-mild to severe wear regime was obtained for different composition samples including base composition to hybrid composition.

Tribological Investigation of AZ91/SiC Magnesium Hybrid Composite under Dry, Oil and Nanofluids Lubricating Conditions

In present research AZ91D/SiC composites were developed using advanced vacuum assisted stir casting process. The tribological properties of AZ91D/SiC composites under dry, oil and nanofluids lubricating conditions were investigated. The nanofluids were prepared by adding the silicon carbide (SiC) nanoparticles to the soluble oil with different weight percentages (1 wt.%, 1.5 wt.%, 2.0 wt.%) for experimentation. The mixing of nanoparticles with base fluid improves the tribological and thermal properties of fluids as the nanoparticles possess higher thermal conductivity than base fluids. The thermal conductivity of SiC nanofluids was evaluated. The wear surfaces under different lubricating conditions (dry, oil and nanofluids) were also analyzed with FESEM. The findings of the study reveal that there was a remarkable enhancement in tribological properties (wear and coefficient of friction) when SiC nanoparticles were added to soluble oil. Furthermore, the selected samples were analyzed using energy-dispersive X-ray spectroscopy (EDS), scanning electron microscope (SEM).

Experimental measurement on friction performance of PDC bearings for oil drilling under different working conditions

Abstract As a kind of superhard material, the polycrystalline diamond compact (PDC) has been extensively used in engineering with its high strength and high wear resistance. Meanwhile, PDC has been increasingly used in bearing design to improve bearing capacity and service life. However, as a bearing material, its friction coefficient under different working conditions is not clear although it is a very important parameter. In this paper, the authors proposed a theoretical model of friction measurement and design a set of measurement rig to investigate the friction characteristics of the PDC bearing. The measurement equipment is developed based on the Coulomb friction model, with the three measurement environments taken into consideration: dry, water and drilling mud. A pair of thrust ball bearing was used in the measurement equipment to equilibrium axial load. But the friction coefficient of thrust ball bearing is proved far less than that of the PDC bearing in the experiment. The frictional coefficient of PDC bearings can be stabilized at about 0.12 under dry friction or water lubrication conditions and increase to 0.2 when tested under drilling fluid environment. Measuring the friction coefficient of PDC bearing -especially under drilling fluid environment can not only provide support for the design of the downhole tool where the bearing friction coefficient obviously affects the feasibility and agility of the tool but also help people to deepen the understanding of PDC materials.

Wetting and tribological properties of superhydrophobic aluminum surfaces with different water adhesion

In this article, a facile and efficient nanosecond laser processing method was carried out to construct a grid of microgrooves on an aluminum surface. After modification with low surface energy materials, various superhydrophobic surfaces with different water adhesion are obtained. The wetting properties of the obtained samples could be regulated by adjusting the number and line spacing (LS) of laser processing steps. The contact angle of the obtained superhydrophobic samples increased with the decrease in LS, while the sliding angle showed the opposite trend. Increasing the number of laser processing steps is beneficial to increase the contact angle and reduce the sliding angle. The wetting mechanism was analyzed to explain the cause of change in the wetting behaviors. The tribological tests showed that the surface textures of superhydrophobic samples improved their tribological properties. What is more, whether it is under dry friction or water lubrication conditions, the obtained superhydrophobic samples with large LS have good anti-friction and wear-resistant ability. The advantages of the facile preparation and excellent tribological properties will definitely expand the use of laser-machined superhydrophobic surfaces.

Tribological characterization of a bearing coated with UHMWPE/GNPs nanocomposite coating

ABSTRACT Polymer nanocomposite coatings with low friction and high wear resistance are being developed to protect aluminium surfaces against wear and tear during dry and boundary lubrication. In the present study, pure and graphene nanoplatelets (GNPs) reinforced ultra-high molecular weight polyethylene (UHMWPE) nanocomposite coatings are deposited on aluminium thrust bearings. Each bearing makes an ROD contact with a metallic disc counterface to simulate the contact configuration in an actual bearing. A set of tests involving pure and reinforced UHMWPE coatings under dry and liquid contact lubrication is conducted. The wear test results reveal that UHMWPE/1 wt-% GNPs performs better than the reference sample significantly. It reduces the friction and wear of aluminium both in the dry and boundary lubrication conditions at different conditions. The 1 wt-% GNPs reinforcement increases the load-bearing capacity of UHMWPE by 440% in the presence of base oil.

Influence of Wax Lubrication on Cutting Performance of Single-Crystal Silicon in Ultraprecision Microgrooving

Lubrication can improve the tool-workpiece interface condition in ultraprecision machining, especially in microgrooving processes. The aim of this study was to compare the effects of dry, liquid (cutting oil), solid (wax) and hybrid (cutting oil and wax) lubrication conditions, on the creation of arc-sectioned microgrooves on single-crystal silicon wafers using a single-crystal diamond tool. Micro cutting forces, chip morphology, and surface quality at different locations of the grooves were investigated. Rose-shaped continuous chips were observed in dry cutting, indicating stable ductile mode material removal. The entrance side of the groove was always smoother than the exit side with a higher degree of phase transformation. Chip adhesions on the tool edge were found in dry and oil lubricated cutting, whereas wax coating could prevent the adhesion. Wax coating played the dual roles of a chip breaker as well as a high-performance lubricant, thus improved the surface integrity. This study demonstrated the capability of using wax coating as an environmentally friendly solid lubricant for microgrooving of single-crystal silicon and possibly for other hard brittle materials.