Lubricant Concentration Research Articles

Flow of lubricated granular material on an inclined plane

We have studied the gravity driven flow of spherical shaped, millimetric sized granular material coated with aspherical, micron-sized, near frictionless lubricant particles. Experiments were performed on an inclined plane using two different sized particles for varying concentrations of the lubricant. The particle volumetric flow rate exhibits a non-monotonic behavior with increasing lubricant concentration. It shows an increase at lower lubricant concentration followed by a decrease at higher lubricant concentration. The lubricant particles adhere to the granular particle surface thereby reducing the inter-particle friction. However, presence of lubricant particles at higher concentration damps out inter-particle collision thereby reducing the interparticle momentum transfer. Non-monotonicity in the observed behavior is then conjectured to arise due to competing effects of inter-particle friction and inter-particle collision. The present work and the overall observed behavior therein provides a simple experimental system to characterize the effects of added lubricant material in pharmaceutical and other relevant industrial applications.

Analysis of the stability of oil-based drilling muds by electrical stability measurements as a function of oil-water ratio, weighting material and lubricant concentrations

Oil-based muds (OBM) used in drilling processes are complex fluids formed by a water-in-oil emulsion stabilized by emulsifiers. Measurements of the electrical stability (ES) are considered directly indicators of mud stability, together with yield point (YP), and fluid loss (FL). In this work, it was studied the effect of oil-water ratio (OWR) in the mud stability using the ES, YP and FL data. To analyze those individuals and paired effects, it was applied a Central Composite Rotational Design (CCRD) planning with three replicates at the central point plus eight and six factorial and axial points. Results showed that all studied factors presented a high influence on the ES results. Additional measurements of rheological properties and fluid loss were carried out to verify and analyze the impact of the composition on the main drilling mud properties. Statistical analysis was also performed to clarify the role of the different factors investigated in this research. The authors observed that several drilling mud compositions are not suitable for the oilfield application, and, by an optimization procedure, an optimal formulation has been proposed.

Tribological performance optimization and synergistic lubrication evolution of Pb‐free FeS/Cu–Bi composites

AbstractThe tribological properties of Pb‐free FeS/Cu–Bi (FCB) self‐lubricating composites were optimised with the Taguchi method. The effects of lubricant content and ball milling time on the anti‐friction and wear resistance of FCB composites were investigated. Then the evolution of the friction interface was observed through interrupted microscopy measurement to reveal its synergistic lubrication mechanism. The results showed that the primary and secondary factors that affected the anti‐friction and wear resistance of the FCB composites were FeS content, Bi content and ball milling time. The synergistic lubrication mechanism of FCB composites was that FeS could prevent the crack from extending with the continuous Bi mesh and could prevent the matrix with Bi debris from peeling off, which was conducive to the formation of a lubricant‐rich tribofilm at the friction interface to improve the tribological properties of the composites.

Determination of oleamide bulk‐to‐surface distribution in polypropylene for medical use depending on sterilization method and storage time

AbstractOleamide is used as a lubricant in the manufacturing and application of polypropylene (PP) medical devices. Samples of PP were prepared with 0, 1500, and 15 000 ppm oleamide content as lubricant. The samples were either left non‐sterile, sterilized with ethylene oxide (ETO), γ‐radiation (γ) or autoclaved (A) and stored for up to 4 weeks. To determine the oleamide bulk‐to‐surface distribution depending on sterilization method and storage time an extraction method and a washing technique were applied. The oleamide content was determined by gas chromatography (GC‐FID) and compared with the coefficient of friction (COF). The COF dependent on the measured lubricant content at the surface. The content of lubricant on the surface depends on the type of sterilization: ETO increased the lubricant content to some extent, γ‐sterilization and autoclaving reduced it. After storage, no migration of the lubricant to the surface could be detected.

Identification of bilge oil with lubricant: Recent oil spill case studies

Oil spills have many adverse effects on the marine environment. Bilge oil spills occur frequently in the sea as a result of maritime accidents or illegal discharge. It is difficult to unambiguously identify the specific sources of such spills because bilge oil contains a mixture of fuel oil and lubricant. In this study, bilge oils with different fuel oil/lubricant ratios were prepared and analyzed using a modified version of the CEN/TR methodology (European Committee for Standardization, 2012). As the lubricant content of bilge oil increased, the intensity of the C20–C24 group, which is the commonly-used normalization compound group for fuel oil in the percentage weathering (PW) plot, also changed. Therefore, the mean area of the C15–C18 group, which was affected by the lubricant content, was used instead. Although heavy fuel oil is usually normalized to a hopane, bilge oil with a high lubricant content cannot be analyzed based on a mass spectrometry (MS)–PW plot; thus, heavy fuel oil-based bilge oil was normalized to a phytane in this study. Although hopanes and styrenes are unsuitable comparison compounds for heavy fuel oil-based bilge oil analysis, for light fuel oil-based bilge oil, hopanes and steranes could be applied as diagnostic ratio comparisons when the lubricant peak was clearly detected in the chromatograms of the spilled and suspected oil samples. By applying the CEN/TR methodology according to this approach, the similarities between spilled and suspected oil samples were more easily revealed. In addition, the field applicability of the proposed method was tested for four actual oil spills.

Prediction of the impact of lubrication on tablet compactibility

The tableting of most pharmaceutical formulations requires the addition of lubricants to reduce ejection forces, prevent tooling damage and tablet defects. The internal addition of lubricants is known to reduce tablet tensile strength, especially of mainly plastically deforming materials. To date, available models show only limited quantitative predictive accuracy for the influence of lubricant concentration on the mechanical strength of tablets. This study aims to fill this gap and present a model based on the Ryshkewitch-Duckworth equation that can estimate the compactibility profiles of lubricated formulations. Binary mixtures of different diluents (microcrystalline cellulose and lactose) were prepared with common lubricants (magnesium stearate and sodium stearyl fumarate) and subsequently tableted. The resulting compactibility profiles were fitted using the Ryshkewitch-Duckworth equation and the derived fit parameters (kb and σ0) were correlated with the lubricant concentration. Subsequently, an empirical model was established which requires a minimum of experimental data and is able to predict the tensile strength of lubricated diluent tablets. Consequently, the developed empirical model is an interesting and valuable addition to the existing multi-component compacting models available and offers the opportunity to accelerate experimentation in the development of new tablet formulations.

MQL assisted face milling of EN-31: Tool wear optimization and its correlation with cutting temperature

EN-31 is one of the difficult-to-cut steels that has applications in the manufacturing of die-casting moulds, high-strength bearing, and several heavy automobile parts. Generation of heat while cutting such material is the principal cause of tool wear and diminishing surface qualities of a machined part. The application of lubricant lowers the temperature of machining but the excess use of lubricant is responsible for increasing the overall cost of machining. Also, due to health and environmental concerns related to lubricant exposure, the application of the Minimum Quantity Lubrication (MQL) technique as an alternative to flood cooling is increased in recent times. In this work, an attempt is made to increase the effectiveness of the MQL technique by optimizing the parameters associated with it. The face milling experimentation on EN-31 steel is accomplished by arranging MQL parameters using Taguchi’s method-based L18 orthogonal array. CRITIC approach is exploited to determine the correlation between the tool flank wear and cutting temperature. The optimum parameter setting for tool flank wear is discovered as 150 ml/h lubricant flow rate, 40 mm spraying distance, 60 % lubricant concentration, and 45° nozzle elevation angle. A reduction of 2.10 % in the value of the flank wear is achieved at the optimal MQL parametric settings.

The friction and Wear behavior of Silicon oil-based Magnetorheological fluid with Solid lubricant

Due to its lower energy consumption, higher mechanical properties and easier to control, magnetorheological(MR) fluid has been widely used in the engineering field. However, the friction and wear behavior of it, which may hinder its applicability, needs to be modified. The tribological behavior of silicon oil-based MR fluid with different types and contents of solid lubricant was investigated on a four-ball machine. The worn surfaces of the steel balls were observed by using a scanning electron microscope (SEM). The results showed that the friction and wear property of silicon oil-based MR fluid could be improved by some solid lubricants. Both of molybdenum disulfide and graphite can decrease friction coefficient of silicon oil-based MR fluid significantly, but graphite has the better wear resistance than molybdenum disulfide. Adding polytetrafluoroethylene (PTFE) can enhance the wear resistance of MR fluid obviously, but the friction coefficient is larger than the first two. The friction and wear property of MR fluid hardly changes by adding boron nitride. Increasing the content of graphite can improve the friction and wear resistance of MR fluid, and the wear resistance of MR fluid has an optimal point when the weight percent of graphite is 2%.

Tribo-effectiveness of co-equal concentration of hard and soft particulates in aluminium matrix

Due to the formation of a transition layer between sliding surfaces, tribological applications of aluminium metal matrix composites constantly endeavour. This greatly reduces the friction and wear of components like automotive engine pistons and brakes. The aluminium matrix was reinforced with an equal number of concentrations of boron carbide hard ceramic particles and graphite solid lubricant. To analyse its concentration potential towards tribo layer quality, the wear test was carried out using pin-on-disk apparatus with parameters like load (10–50 N) and sliding speeds of (0.7, 1.4, and 2.1 m/s under a dry sliding condition. The behaviour of tribo composites with equal share concentrations of boron carbide and graphite (5%, 10%, and 15%) was unique rather than monotonically increasing reinforced composites. The surfaces were worn after SEM analysis of wear tests. According to the experimental results, the wear rate of a 5% equal concentration composite decreases with increasing load. The wear of the 10% concentration composite decreased by almost 2 times that of the 5% composite. Similarly, the wear of a 15% composite decreases with every 10% composite. However, the coefficient of friction (COF) of the 10% composite decreased by one time when compared to the 5% composite, whereas the COF of the 15% composite was 2 times less than the 10% composite.

Optimization and Nanoreinforcements of Lubricant Concentration for Steel Sheet Forming Process

In metal-mechanic industry, lubricants are applied to improve products’ quality and tools useful life, while reducing friction and wear, also removing the generated heat during the material processing. Tribological evaluations are performed varying the water content of two widely used lubricants in automotive metal-forming operations. Evaluations are first performed to determine the optimal lubricant dilutions, followed by reinforcement of 2D-nanostructures of hexagonal Boron Nitride (h-BN). Tribological characterization under extreme pressures (EP) are performed with a four-ball tribometer according to the Institute for Sustainable Technologies –National Research Institute (ITeE-PIB) Polish method under scuffing conditions. The optimized concentrations are determined for Ecodraw and Montgomery lubricants, representing a 28% and 3% improvement in pressure loss limit at 1:8 and 1:6 concentrations, respectively. Block-on-ring tribotest is used to determine the coefficient of friction (COF) of the optimized lubricant dilutions and h-BN nanolubricants, which represent ~10% improvement. These results could be attributed to diverse factors such as a layering mechanism of the 2D nanostructures, soft van der Waals forces between 2D h-BN layers, and the deposition of h-BN on the worn surface, decreasing the shearing stress and COF. Finally, thermal conductivity evaluations showed an enhancement by 30% and 15% with addition of h-BN, demonstrating the potential of 2D nanostructures for improving the efficiency on antiwear and thermal transport.

Investigation of second phase concentration effects on tribological and electrical properties of Cu–WS2 composites

In this preliminary study, a set of self-lubricating copper-tungsten disulfide (Cu-WS2) composites are prepared via a powder metallurgy route to analyze the effects of solid lubricant concentration on their tribological, electrical and wettability properties. An extensive characterization is performed to preliminarily assess the potential application of these metal matrix composites (MMCs) in sliding electrical contacts working under harsh conditions. The experimental results reveal the beneficial effect of WS2 on the wear behavior of the prepared composites, as demonstrated by friction coefficient, specific wear rate and wear coefficients results. A second phase content in the 10–15 wt% range appears to guarantee the better combination of the desired features.

A Machine Learning Approach to Predict the Performance of Refrigerator and Air Conditioning Using Gaussian Process Regression and Support Vector Methods

Aim: Develop machine learning models for the performance of refrigerator and airconditioning system. Background: The Coefficient Of Performance (COP) of Refrigerator and Air-Conditioning (RAC) is a complex function of evaporative temperature and concentration of nano-particle in lubricants. In recent years, researchers focus on experimental study for improvement of COP. Further, few researchers applied simulation techniques such as fuzzy system, Artificial Neural Network (ANN), simulated annealing, etc. to the Vapour Compression Refrigeration (VCR) cycle. There is a scarcity of modeling research work for the performance of RAC system. Objective: The study aims to develop the machine learning predictive models for the performance of refrigerator and air-conditioning system using experimental data. Methods: The experiment was performed on VCR system to determine COP. Three different concentration of lubricants (added 0.5, 1.0 and 1.5g nano-TiO2 particle on 1 liter of Polyolester (POE) oil) were used. The experimentally calculated COP was used to train and test the machine learning models. Gaussian Process Regression (GPR) and Support Vector Regression (SVR) methods were applied to develop the models. Results: The experimental result reveals that the COP increases with increasing the concentration (of nano particles) at a given temperature. The addition of 0.5 and 1.0g TiO2 in the POE oil shows better rate of increment in the COP in comparison to addition of 1.5g TiO2 in the POE oil. Machine learning models using GPR and SVR with RBF kernel function is the most appropriate machine learning model for the nonlinear relationship between the output parameter (COP) and the input parameter (evaporative temperature and concentration of TiO2). Conclusion: The present study was conducted to investigate the machine learning approaches for performance of RAC system using experimental data sets. The experimental result shows that R134a and TiO2-POE nanolubricant work efficiently and the coefficient of performance of VCR system increases with concentration of nano-particle. The developed model performance is compared using coefficient of correlation and RSME values. After comparison, it is concluded that RBF based GPR model is the best fit machine learning model to predict the COP in the context of any other model for this data set.

Optimization of surface integrity in face milling of AISI 52,100 alloy steel using Taguchi based grey relational analysis

The challenging demand to achieve high quality of the manufactured components, has resulted in development of precision machining processes, which serve as a good alternative to the grinding process. However, high-temperature generation is the major problem in the cutting areas during the machining of difficult-to-cut material; this temperature affects the surface integrity. Therefore, lubrication is required for the removal of heat due to temperature rise at the cutting zone. Because of the adverse effect of flood cooling on the worker's health and the environment, MQL is a suitable substitute to flood cooling. In this study, the effect of process parameters such as cutting speed, feed rate, Depth of cut, lubricant concentration, and flow rate on surface roughness and microhardness was studied during the face milling of AISI 52,100 alloy steel using MQL. Taguchi-based L-27 orthogonal array was used, and multi-response optimization was done using grey relational analysis (GRA). The Depth of cut was the highly influencing factor followed by feed rate, cutting speed, flow rate, and lubricant concentration. The optimum process parameters for the optimized condition for surface roughness and microhardness were cutting speed 150 m/min, feed rate 0.1 mm/rev, Depth of cut 0.3 mm, lubricant concentration 60%, and flow rate 100 ml/hr.

Enhancing the wide temperature dry sliding tribological performance of nickle-alloy by adding MoS2/CaF2

In this paper, the nickle-alloy matrix composites with different content of MoS2 (0, 5, 10, 15, 20 wt. %) and CaF2 (0, 5 wt. %) were fabricated by hot pressed sintering method and their frictional behavior was tested from 25 °C to 700 °C. Results showed that the testing temperature and solid lubricant content had significant effect on the frictional behaviors of the composites. For the materials with 10, 15, 20 wt. % MoS2, low friction coefficients of 0.16–0.3 and wear rates of (1.6–14.8) × 10−5 mm3 N−1 m−1 were observed as testing temperature up to 200 °C. The wear mechanisms were analyzed based on the morphologies and chemical composition of the worn surface.

Predicting lubricants effect on tablet sticking using ketoprofen as model drug and evaluating sticking propensity using different metals and powder rheology

Tablet sticking occurrence is a persistent, costly, and time-consuming problem that needs to be resolved. Predicting the sticking tendency of a new formulation has been very difficult during the development batches because of short runs and limited data. A model formulation comprising ketoprofen and microcrystalline cellulose was used to predict the effect of magnesium stearate and sodium stearyl fumarate on the occurrence of tablet sticking relative to different punch metals. Lubricant amounts were varied from 0.0% to 2.0 %w/w. Five different metal coupons were used to represent punch metals. The sticking index (SI) of each formulation relative to each metal coupon was determined by measuring angle of internal friction and angle of wall friction by performing shear cell test and wall friction test, respectively. The SI was used to predict each formulation's sticking tendency rank order relative to metal coupon. Both lubricants show a decrease in the powder blend's sticking propensity with increased lubricant concentration. The predicted sticking propensity rank order was then validated by the compression study. The result suggests that the SI can be used to predict tablet sticking, such as by changing the composition of the formulation or changing the punch metal during tablet compression.

Molybdenum disulphide—A traditional external lubricant that shows interesting interphase properties in pulp‐based composites

AbstractCompression molded composites were prepared through a water‐assisted mixing of an aqueous suspension of poly(ethylene‐co‐acrylic acid), additive, and pulp fibers [thermomechanical pulp (TMP) or dissolving pulp (DP)]. The lubricating additives used were magnesium stearate (MgSt) and molybdenum disulphide (MoS2). The composite materials had dry pulp contents ranging from 30 to 70 wt% and 5 wt% additive relative to the weight of the pulp. The adsorption of the additives onto the fibers was confirmed by scanning electron microscopy and energy dispersive X‐ray analysis. DMA showed that MgSt and MoS2 gave similar interphase properties for the TMP samples at all loading contents, but the combination of MgSt and MoS2 improved the overall properties of the DP‐based composites. The tensile modulus, at 70 wt% fiber content (TMP or DP), increased compared to the matrix by a factor of 6.3 and 8.1, without lubricants, and by a factor of 8 and 10.7, with lubricants, respectively. The increase in melt viscosity observed for the lubricated samples was greater for the TMP‐based samples containing MoS2. At a lubricant content of 5 wt%, in 30 wt% TMP, the MoS2 behaved as both a lubricant and compatibilizer.

A Theoretical Analysis for The Characteristics of Human Articular Joints.(Dept.M)

A simple model of two parallel plates with reference to human articular joints was suggested and studied in the presence of synovial fluid, Variation of pressure, load capacity, time of approach, concentration of lubricant, minimum film thickness and the effect of cartilage porosity upon lubrication, have been investigated. The mathematical analysis was based on the continuity of pressure and velocities at the interface of the synovial fluid film and the three car ilage layers possessing different porosities. The study brings out many valuable and important results which are in good agreement with earlier experimental observations.

EFFECT OF VARIATION OF LUBRICANT CONCENTRATION (MAGNESIUM STEARATE) ON THE PHYSICAL QUALITY OF METOCLOPRAMID HCl TABLETS WITH DIRECT PRINTING METHOD

Metoclopramide HCl is used to relieve nausea and vomiting. Market availability in the form of tablets, syrup and injection. The most preferred drug use by patients is oral medication because of its ease of use. Chewable tablets are a new product as an alternative for treatment in pediatric and adult patients who have difficulty swallowing drugs. This study aims to formulate the chewable tablet preparations of metoclopramide HCl using variations in lubricant concentrations. The variations of magnesium stearate with concentrations of 1%, 2%, and 3% using the direct printing method made to obtain a better physical quality test including organoleptics, weight uniformity, uniformity of size, tablet hardness, tablet brittleness, tablet crush time, uniformity of content. The results of the physical quality test were statistically analyzed using one way ANOVA to determine the effect of variations in the concentration of lubricants on the characteristics of chewable tablets. The results showed that variations in the concentration of magnesium stearate lubricant in the manufacture of metoclopramide HCl chewable tablets had an effect on the physical quality of metoclopramide HCl chewable tablets. The concentration of magnesium stearate which produces metoclopramide HCl chewable tablets with good physical properties is 2%.

Optimization of bionic textured parameter to improve the tribological performance of AISI 4140 self-lubricating composite through response surface methodology

Inspired by microstructures on tree frog surface, this article designs bionic micro-texture combined with solid lubrication SnAgCu to improve the tribological properties of AISI 4140 steel. The optimized bionic texture parameters are obtained by RSM. Tribological tests were carried out on Optimal Test (OT), Optimal Prediction (OP) and Control Group (CG). Compared with OT, the discontinuous layer phenomenon on wear track of OP is significantly reduced, lubricant content is increased, and numbers of pits near the textures are reduced. A uniform thickness of 2.4 µm lubricating film was formed on worn surface of OP, and the film was well bonded with substrate. Consequently, optimizing the micro-texture by RSM can significantly improve the tribological properties of AISI 4140 steel.

Application of air-vortex thread in sewing operation

Attempts have been made to use air-vortex spun yarn of 30s and 40s count as sewing thread by using 2.9% and 5.9% concentrations of lubricant. Yarn strength, elongation, hairiness, dry heat shrinkage, yarn abrasion, snarling of yarn after heat setting, loop strength and knot strength of air-vortex spun sewing threads have been studied. It is observed that the sewing thread made with 5.9% concentration of lubricant performs better in comparison to that made with 2.9% lubrication level. Seam strength and efficiency of different types of seam made by air-vortex sewing threads have also been studied. Flat and lapped seams are found to produce higher seam strength and seam efficiency. Seam strength and efficiency improve with increase in the concentration of lubricant in both 30S and 40S yarn. Sewing performance of threads has also been analysed by testing seam strength, seam efficiency and thread breakage during sewing.