Selection Of Lubricants Research Articles

Investigating the Effects of Lubricant Infusion Methods on Polymer SLIPS.

Slippery lubricant infused porous surfaces (SLIPSs) are promising bioinspired surfaces with self-healing and droplet wetting properties, among many others, that are desirable due to their range of applications. Recently, there have been many developments in the SLIPS field regarding the creation of textured surfaces and lubricant selection. However, there is a lack of knowledge regarding the method of lubricant infusion. In this study, we aim to fill this void by investigating different infusion methods that impose external forces on the lubricant. We developed our SLIPS by hot embossing nanostructures onto polypropylene by using molds that were laser micromachined. These textured surfaces were then infused with silicone oil using three different infusion methods: ultrasonication, vacuum, and hydrostatic pressure. We analyzed the wettability and slipperiness of the SLIPS by evaluating the critical tilt angle and comparing the sliding velocities of water droplets on each sample at a tilt angle of 20°. Additionally, the durability of the SLIPS was tested by dropping 50 successive water drops onto the samples and evaluating the droplet-surface interactions throughout. The sonicated infusion method yielded SLIPS that performed the best with a contact angle hysteresis of 13°, a critical tilt angle of 18.3°, a sliding velocity of 1.66 mm/s, and the least accumulation of droplets over time with use. These values are greatly improved when compared to the control sample where lubricant was simply dripped on, which resulted in a contact angle hysteresis of 20°, a critical tilt angle of 26.3°, and a sliding velocity of 0.23 mm/s. The sonicated and drip infusion methods were also compared with different materials (stainless steel) and different textures (microstructures). It was found that the improvement in slipperiness using the sonicated infusion method is prominent for nanoscale textures on both stainless steel and polypropylene. In this study, we discuss the challenges with oil depletion in SLIPS (cloaking and wetting ridges) and with the selection of contact angle measurement methods. While further investigation as to why certain applied forces during infusion yield better SLIPS is warranted, these forces greatly affect the outcome. This work suggests that researchers should consider using sonication or other methods of lubricant infusion that apply external forces as infusion techniques to yield better SLIPS on the nanoscale.

Wear protection assessment of ultralow viscosity lubricants in high-power-density engines: A novel wear prediction algorithm

Durability and reliability have been studied for decades through intensive trial-error experimentation. However, there are numerous fields of application where the costs associated with this approach are not acceptable. In lubricated machines with severe dynamic loads, such as high-power-density engines, simulation tools offer clear advantages over intensive testing. Prototypes and multiple scenarios can be cost-effectively simulated to assess different lubricants and engine configurations. The work presented here details the study of wear based on a validated elastohydrodynamic (EHD) simulation model of the connecting rod journal bearing. This model accounts for elastic deformation through a connecting rod finite element model (FEM). In addition, multiple lubricant rheological and tribological dependences, determined by specific experimental tests, are applied in the model through their interaction with the simulation software. Correspondingly, a novel wear algorithm is proposed to predict wear depth over time evolution along a proposed wear cycle based on the typical working ranges of high-performance engines. A final assessment is presented to compare 4 different ultralow-viscosity lubricants in their protective performance under severe conditions. The results show the evolution of the wear load and wear depth over the wear cycle. This evaluation is key to describing a lubricant selection procedure for high-power-density engines.

Rolling Element Bearing Damage in the Presence of Applied Electric Current

Modern wind turbines and battery electric vehicles have bearings in close proximity to electrical generators, motors, and inverters. These systems have motivated new research focused on damage mechanisms associated with low- and high-level electric currents in rolling element bearings. This work presents a study on the influence of applied electric current and lubricant selection on bearing surface damage. Direct current was applied to a rotating tapered roller bearing with axial load and oil lubrication. Tests were conducted with various levels of applied current and two different oils (additized and non-additized). Micropitting, white etching cracking (WEC), and the formation of a surface white layer were investigated using both optical microscopy and scanning electron microscopy. Some of the tested bearings had black oxide surface treatment on their rollers and raceways. The black oxide was evaluated with regard to the prevention of the WEC damage mode. The occurrence of the described damage modes depended on the type of oil used and the application of electric current. Higher electric currents increased bearing surface damage in these tests.

Utjecaj ekscentrične porivne sile na odabir statvenog kliznog ležaja

Stern tube slide bearing of the shaft line of the ship's propulsion system causes losses during operation. Friction and material wear of the tribosystem occur. One of the reasons is the different navigating regimes of the ship, which have an influence on the formation of the velocity field on the ship's propeller. The variable velocity field defines the magnitude and the position of the thrust force. The methodology presented in this paper is based on the fact of the existence of the eccentricity of the thrust force, i.e. loads due to the action of the moment of the eccentric thrust force. Due to the changing position of the thrust force, the curvature of the elastic line of the sleeve inside the stern tube bearing, which is mostly spatial, changes. Spatial elastic line of the sleeve has an influence on the working area of the slide bearing. Therefore, the importance of a sufficient thickness of the lubricant layer for lubrication in relation to these changes was highlighted. In this paper, this is the initial criterion for the selection of materials and lubricants of the stern tube bearing. An equally important criterion would be to define the possible harmful impact of lubricant leakage with particles of bearing bush material on the ecosystem. In order to facilitate the whole process, the simplified analytical model is presented, which can be used in the initial stage of stern tube bearing selection. Such a model allows a simpler analysis of the influence of the elastic line on the condition of the stern tube bearing due to the loading by the weight of the ship's propeller and by the moment of the eccentric thrust force. The procedure for the initial selection of the stern tube bearing created by this methodological approach could have its practical application. For this reason, the paper analyzed different navigating regimes and their influence on the working area of the stern tube slide bearing. The obtained results can be useful in the selection of materials and lubricants for the stern tube bearing tribosystem.

Integration of objective weighting methods for criteria and MCDM methods: application in material selection

Determining weights for criteria is an extremely crucial step in the process of selecting an option based on multiple criteria, also known as Multi-Criteria Decision Making (MCDM). This article presents the combination of five objective weighting methods for criteria with three MCDM methods in the context of material selection. The five objective weighting methods considered are Entropy, MEREC (Method based on the Removal Effects of Criteria), LOPCOW (Logarithmic Percentage Change-driven Objective Weighting), CRITIC (Criteria Importance Through Intercriteria Correlation), and MEAN. The three MCDM methods employed are MARA (Magnitude of the Area for the Ranking of Alternatives), RAM (Root Assessment Method), and PIV (Proximity Indexed Value). Material selection investigations were conducted in three different cases, including lubricant selection for two-stroke engines, material selection for manufacturing screw shafts, and material selection for manufacturing gears. The Spearman's rank correlation coefficient was calculated to assess the stability of ranking the alternatives using different MCDM methods. The combinations of objective weighting methods and MCDM methods were evaluated based on factors such as consistency in identifying the best material type, range, average value, and median of each set of Spearman's rank correlation coefficients. Two significant findings were identified. First, the weights of criteria calculated using LOPCOW method appear to be inversely related to those calculated using the Entropy method. Second, among the three MCDM methods used, MARA was identified as the most suiTable for lubricant selection for two-stroke engines, RAM was found to be the most suiTable for material selection for screw shafts and gears. The best material type in each case was also determined

The dynamic model of lubricating layer formation/destruction processes in boundary and mixed friction modes

The article is dedicated to studies of self-organization processes evolving in time in boundary lubricant layers. The essence of the article consists in use of the model of the connected processes of formation and destruction of a shielding delayed lubricant layer based on differential equations similar to that which are used for description in time of dynamics of probabilities of states of a single channel system of queueing theory with Poisson stream of queries and exponential service (Kolmogorov-Chapman equations). Proposed method involves introducing concepts: the intensity of delayed layer growth - l and the intensity of delayed layer destruction - m. This kind of concepts, in author’s opinion, is organically inherent in atomic-scale molecular systems consisting of large numbers of particles with many significant connections between them, all of which are impossible to describe and simulate. The studies of lubricating layers formation/destruction processes and structure of boundary lubricant layers in the medium of paraffin oil as a lubricant at different sliding speeds and loads were made. It was established that minimal values of friction coefficient were characteristic for layers with high intensity of delayed layer growth and high values of limit thickness. Proposed approach to modeling phenomena of self-organization in boundary lubricant layer can be useful for understanding the mechanism of lubricating action in conditions of boundary and mixed friction and applied for solving some practical problems related to the selection of effective lubricants for tribo couplings of the specified configuration and loading parameters.

Orally disintegrating tablets: formulation, preparation, and quality control assessment

Orally disintegrating tablets (ODTs) are a new formulation that dissolves in saliva within seconds, and there is no need to drink water. Due to its many benefits, this dosage form is an effective way to administer active pharmacological substances, especially for pediatric, geriatric, psychiatric, paralyzed, and bedridden patients. ODTs have been shown to have superior patient compatibility and drug solubility in numerous studies that have compared this tablet form with conventional forms in vitro and in vivo. There are many substances used to achieve enhanced characteristics, including super disintegrants such as croscarmellose sodium and crospovidone to achieve rapid disintegration and dissolution, and selection of appropriate diluent, binder, sweetening agents, flavoring materials, and lubricant are required to make tablets dissolve quickly. This dosage type can be prepared in several techniques, including direct compression, sublimation, freeze-drying, lyophilization, spray drying, molding, Process of cotton candy, Massextrusion, phase extrusion, and Melt Granulation. Formulation and selection of appropriate excipients are discussed, and ODTs' preparation techniques are illustrated in this review. Laboratory evaluation and quality control measures, including precompression (micromeritics parameters) to adjust formulation and obtain the optimized formulations to be produced and scale up and post-compression parameters for ODTs, are also discussed in this review.

Impact of Three Chainsaw Lubricants on Forest Soil Bacterial Community, Soil Respiration and Seedling Growth

Lubricants are applied onto chainsaw blades to achieve their optimum cutting performance; however, during logging or timber operations, lubricants may penetrate the forest soil. The persistent organic pollutants in lubricants may cause environmental damage, and different types of lubricants vary in terms of their environmental impact. Hence, selecting appropriate lubricants for timber operations is important for sustainable forest management. In this study, the effects of three lubricant types—biodegradable oil (bio-oil), petroleum-based bar-and-chain oil (mineral oil), and petroleum-based recycled oil (recycled oil)—on soil health were evaluated. The study was conducted in a controlled nursery setting, simulating post-logging reforestation. Sixteen types of polycyclic aromatic hydrocarbons and the total petroleum hydrocarbon concentrations in the soil samples were analyzed. Bio-oil facilitated faster recovery from soil contamination, whereas mineral oil exhibited slow and incomplete recovery. Recycled lubricants appear to be more environmentally sustainable options, indicating lower long-term soil contamination risks than petroleum-based lubricants. From a productivity perspective, the lubricant that supported the growth of seedlings was bio-oil. The findings of our study contribute to responsible lubricant selection for enhancing the overall health and sustainability of forest ecosystems.

Dynamic characteristics of refrigerant and lubricant in R290 rolling piston compressor of low-temperature air to water heat pump (LT-AWHP) during defrosting cycle

The dynamic characteristics of refrigerant and lubricant in R290 rolling piston compressor used in LT-AWHP (ambient temperature (ta) of 7 ∼ −30 °C) are not clear at present. In this study, the changing characteristics of suction and discharge pressure and temperature, physical properties of oil sump (temperature, viscosity, solubility) and oil sump liquid level in the high pressure shell double-cylinder rolling piston compressor during defrosting cycle (steady state→ defrosting→ steady state) were experimentally researched in a R290 LT-AWHP with the rated power consumption of 1.9 kW using PAG40 and POE68 lubricants at ta of −12 and −20 °C. The results show that, the defrosting time and the change rule of oil sump physical properties are different when completely miscible oil and partially miscible oil used, but the defrosting time (about 3 – 5 min) is less than that of the R290 air to air heat pump (about 8 min). After defrosting, the fluid in the upside of compressor shell remains liquid and gas mixture for a long time, which would decrease total heating performance of the heat pump. After defrosting, oil sump viscosity is lower than the steady state value for a long time after discharge pressure is stabilized again. Within a period after the four-way valve reversing, the oil sump liquid level drops a lot, which may result in metal wear for insufficient oil supply on the side of sliding vane. This research would promote the improvement of defrosting process and provide guidance for the lubricant selection of R290 LT-AWHP.

Influence of Concentration of Sodium Metasilicate and Descaling on the High Temperature Lubricating Effects Evaluated by Hot Rolling Mill

Lubricant is vital to improve energy efficiency and workpiece durability for the moving counterpart. High-temperature lubricants are important for the hot rolling process to reduce the rolling force and protect the roller and the strips. The current paper concerns eco-friendly sodium metasilicate as a high-temperature lubricant. A hot rolling mill is employed to evaluate the lubrication effect of sodium metasilicate. The influence of crucial factors of concentration of lubricant and descaling is discussed; the rolled surface was analyzed by scanning electron microscopy, energy dispersive spectroscopy, and 3D profilometer. The results depict that the sodium metasilicate can reduce the rolling force by about 7.8% when the concentration of sodium metasilicate is 18% and above, and descaling of the hot stripe makes the lubrication effect more effective, which can reach a 12.7% reduction in the rolling force. This lubrication is attributed to the formed melts of the sodium silicate layer that offers an easy shearing interface. For the un-descaled samples, the lubricant will be compacted and mixed with the oxide scale, and weakens the lubrication effect. This work suggests that sodium metasilicate can be a high-temperature lubricant for hot rolling; descaling is vital, not only for the quality of the product but also for the efficiency of the lubricant. This work will also be useful for the concentration selection of glass lubricant.

Optimized selection of fluid lubricant for cylindrical roller bearings under elastohydrodynamic lubrication

Roller bearings are widely used in machinery. Keeping the contact surfaces of bearings properly lubricated strongly mitigates wear effects, improving bearing fatigue life. Therefore, systematically selecting the lubricant fluid that satisfies bearing operation conditions allows the lubricating layer to be able to carry the applied load, the operating temperature, and the roughness on contact. The nonlinear constrained optimization method is used for lubricant selection, seeking to find the fluid that best fits the bearing operation conditions. Roller bearing lubrication is characteristically elastohydrodynamic (EHL); namely, the Hertz theory describes the load applied on the contacts of a cylindrical roller bearing, and the Stribeck condition classifies the tribological condition of the surfaces in contact. This work concludes that roughness and speed are the most important parameters to consider when choosing a fluid lubricant.

Influence of Grease Properties on False Brinelling Damage of Rolling Bearings

False brinelling damage in rolling bearings can lead to reduced component lifetimes and increased noise emissions, adversely affecting machine performance. Therefore, minimizing or avoiding such damage is very important. Environmental or operating conditions that can lead to false brinelling damage often cannot be avoided. Alternatively, such damage can be significantly reduced with suitable lubricants. This study utilized a test method from the research project FVA 540 to examine the impact of the base oil viscosity and NLGI class of greases on false brinelling damage at different temperatures. The results showed a clear dependency between the base oil viscosity of greases and the extent of false brinelling damage. Two different thickeners (lithium hydroxystearate/diurea) and different base oil types (PAO/esters) were investigated for this purpose. The results indicate that temperature had a significant effect on the physical and rheological properties of greases and show the potential for reducing false brinelling damage through the selection of appropriate lubricants. These results provide valuable information to improve the performance and lifetime of rolling bearings in industrial settings.

Experimental-numerical analysis to determine the efficiency of industrial lubricants in wire drawing process

Drawing is a manufacturing process that consists of indirect deformation by pulling the material through a tool with a conical geometry. The process is usually performed at room temperature (cold forming), so the selection of effective lubricants is critical. If lubrication is inadequate, there is a high risk that both, tool and the manufactured wire, will fail. In this study, annealed AISI 1020 steel rods were drawn and the effectiveness of three different industrial lubricants was tested. During the process, the drawing force values were recorded and used to determine the friction coefficient that developed under each lubrication condition. Numerical simulations were performed to further understand the process. Based on the experimental and numerical results, qualitative and quantitative analysis were performed for each condition. Among the different lubricants used in this study, zinc stearate showed the lowest value for drawing force, 18.8 kN, followed by Lub A and B with values of 20 kN and 20.6 kN, respectively. The numerical models showed excellent approximation to the force values determined in the tests. The values for the coefficient of friction obtained by both the numerical analysis and the empirical model indicate that zinc stearate has the highest lubricating effect among the lubricants focused on this study.

Evaluation of FeCrNiMo coating Tribological performance produced through laser directed energy deposition sliding under biodegradable oils

Improving the performance of mechanical components and reducing machine energy consumption involves the correct selection of lubricants and their contact surfaces. The use of biodegradable hydraulic fluids along with less environmental impact surfaces is one example. In this sense, the following paper aims to analyze the behavior of mineral oil (HLP) and biodegradable oils (HEPR and HETG) submitted to a sliding with pins manufactured in PTFE and Al2O3 against a flat substrate coated with FeCrNiMo by the Laser Directed Energy Deposition (L-DED) process. Coatings by this replacement deposition process are proving to be a promising alternative in the replacement of hard chromium, a harmful material to human health. The slip tests were performed in a pin-on-disk tribometer using different loads in order to assess lubrication and wear regimes. In the tests, the average of the friction coefficients (μ) obtained was μHETG = 0.072, μHLP = 0.026 and μHEPR = 0.011, besides well-defined lubrication regimes. In the wear analysis, it was observed that the highest concentrations of Zn and P additives, found in HEPR, reduced surface damage. The main wear mechanisms identified were scratching, microcracking, microploughing and detachment. Consistent with the results mentioned, the largest volume removed from the coating was with the use of HETG vegetable oil, about 41% more than HEPR.

Experimental study on the tribological behavior of ceramic disks for application in mixer taps under different lubrication conditions

PurposeThe evaluation of the haptics of water taps and wear-related changes during usage usually involves time- and cost-intensive testing. The purpose of this paper is to abstract the tribo-system between technical ceramic disks of water tap mixer cartridges to the model level and study the tribological behavior.Design/methodology/approachThe friction and wear behavior was studied by means of an alumina ball-on-original alumina disk setup at different temperatures as well as under dry conditions and under lubrication by different greases. Thereby, the frictional behavior was measured in situ, and the wear losses were analyzed by means of laser scanning microscopy.FindingsIt was shown that friction and wear can behave in a contrasting way, whereby one grease might lead to low friction, that is, an easy-going movability of the water tap, but to increased wear losses. The latter, in turn, is an indicator for the usability and service life, which cannot be explained from friction alone. Thereby, the viscosity of the base oil, the grease consistency and additives were identified as relevant grease formulation parameters to allow for fluid film (re-)formation and removal of wear particles.Originality/valueTo the authors’ best knowledge, this is the first approach to systematically analyze the friction and wear behavior of technical ceramic disks of water tap mixer cartridges in dependency on the temperature as well as the used lubricating grease. This approach is relevant for developing screening test strategies as well as for the selection of lubricants for water tap applications.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-11-2022-0334/

Sebaceous gland-inspired self-lubricated de-icing coating by continuously secreting lubricants

In recent years, oil-contained deicing materials have aroused peoples' concern due to their weak ice adhesion feature. Yet the loss of lubricant on oil-contained surface caused by contact or volatilization should be considered. Oily sebum secreted by sebaceous glands lubricates and moisturizes our skin, and can be reproduced continuously even after daily cleaning. In this work, inspired by sebaceous glands, a self-lubricant (SL) coating with ultra-low ice adhesion and excellent deicing durability was designed via continuously secreting lubricants. To determine the suitable simulant of oily sebum, the tribological tests and theoretical simulation analysis of lubricant on ice were conducted, confirming the effect of polydimethylsiloxane (PDMS) lubricants. By well mixing lubricant and resin, and sebaceous glands-like structures formed in coating matrix after curing, which endowed coating with lubricant storage feature and sebum-like secretion structure. The affinity of PDMS molecules to ice and the regeneration of lubricant film ensured the deicing durability of coating. Ice adhesion strength can be kept below 100 kPa even after 100 icing-deicing cycles, and can recover low ice adhesion strength (~50 kPa) via lubricant secreting. This work highlights the importance of lubricant selection and gives a new vision to designing durable icephobic materials.

Einfluss des Substratmaterials bei der Transferschmierung von Stahl- Bronze-Kontakten mit PA66-PTFE-cb Trockenschmierstoffen

In this work, the dependence of the friction and wear behaviour in dry-lubricated steel-bronze contact on the dry lubricant used and on the substrate material (steel or bronze) under constant load was investigated. For this purpose, a block two-disc test rig was used, with the dry lubricants PA66-PTFE-cb as blocks, which were produced via chemical bonding (cb) of polyamide 66 (PA 66) and radiation-modified polytetrafluoroethylene (PTFE). The results provide a good basis for the selection of a suitable dry lubricant and the counter body for the transfer of the dry lubricant in dry lubricated worm gears consisting of a steel worm and a bronze wheel.

Beyond tablets’ physical characteristics: Incorporating environmental sustainability metrics into the selection of lubricants for pharmaceutical tableting

Despite lubricants' indispensable roles in the production of pharmaceutical tablets. The selection of lubricant for pharmaceutical tableting has been largely empirical, where most tablets are produced using magnesium stearate (MgSt) as the lubricant. Even though many other lubricants (e.g., inorganic materials, polymers, surfactants) can deliver comparable lubrication efficiency as MgSt and often produce tablets with superior characteristics, these alternative lubricants remain not widely used. As the pharmaceutical industry strives to improve the environmental sustainability of its manufacturing, the present work aimed to employ environmental sustainability metrics as one of the decision tools (the other being the tablet's characteristics) in the lubricant selection process. Ibuprofen tablets prepared with four types of lubricants, i.e., MgSt, talc, polyethylene glycol (PEG 6000), and sodium dodecyl sulfate (SDS), were studied. For each lubricant, environmental impacts of its production from raw materials were quantitatively characterized by life cycle assessment (LCA). Subsequently, LCA of ibuprofen tablets prepared using different lubricants was performed. Kilo-scale tableting experiments were carried out to generate material and energy flow data for the LCA. The results of the tableting experiments showed that ibuprofen tablets' characteristics were minimally affected by the type of lubricant used and all tablets could meet the criteria for friability, weight variation, drug content uniformity, and dissolution. The LCA results revealed that PEG 6000 had the best environmental sustainability profile, followed by talc, MgSt, and SDS. Owing to PEG 6000's superior sustainability profile, tablets prepared using PEG 6000 as the lubricant generated smaller environmental impacts than tablets prepared using MgSt. Therefore, the incorporation of environmental sustainability metrics into the lubricant selection methodology can improve the environmental sustainability of pharmaceutical tablet production.

Effective use of motor oil resources of the tractor of the company “Claas” in the conditions of Uzbekistan

AnnotationThe article describes in detail the reliable operation of modern high-performance and complex “CLAAS” techniques, the correct selection of lubricants and compliance with the optimal operating procedure, as well as the results of the analysis of friction elements of motor oils. It is necessary to compare the quality indicators determined on the basis of research and the concentration of friction elements in the oil with standard values. In order to determine the recommended engine oil change intervals in the engines of CLAAS tractors, it is necessary to determine their quality indicators and the concentration of friction elements in the oil. In order to maintain the performance of the oil, it is recommended to add additives during operation. Study of wear conditions of oils used in internal combustion engines. Determination and justification of the limit working life of oils used in internal combustion engines. Study and justification of properties of interchangeable oils used in internal combustion engines. It is necessary to develop scientific justification and recommendations for increasing the service life of the oils used in internal combustion engines.

Identification of Influencing Factors in Machine Hammer Peening with Consideration of Lubricant Influences

Lightweight construction and performance requirements in the automotive industry have resulted in increased power density. At the same time, this increases the load on the workpieces. To counteract the resulting wear, either a more wear-resistant material may be applied or the functional surface may be specifically modified against wear. Machine hammer peening (MHP) is a process for such a targeted adjustment of the functional surface and the surface area properties. MHP is a mechanical surface treatment, which increases the wear resistance of the workpieces by introducing residual compressive stresses and work hardening as well as by smoothing or structuring the surface. To ensure an accurate adjustment of the surface properties, the influencing factors (material, process parameters and lubricant) and their interactions must be sufficiently well studied and understood. In particular, the influence of the lubricant on the surface area properties has not yet been adequately investigated. The objective of the work presented in this paper was to provide a deeper insight into the influence of the type of lubricant on the resulting surface properties in terms of roughness, residual stresses and hardness. The lubricant’s influence was investigated using a partial factorial experimental design. Additional factors investigated, besides the choice of lubricant, were stroke, distance of indentation and step over distance. The results show a strong influence of the lubricant selection, especially on the resulting surface roughness. For the same process parameters, a deviation of 540 % in the resulting surface roughness was measured between two surfaces machined with different lubricants.