Grease Lubrication Research Articles

Forming Parameters and Optimization of A5052 in SPIF Process

Forming a metallic sheet along with the consideration of computer simulation and experiment had benefited the milling industry for a long time. The ideal forming, without an error, is a concerning topic. So, the computer simulation had the advantage then direct forming. To observe the results before doing the real experiments simulation comes handy. Which helped to set the parameters for the milling process for the single point incremental forming (SPIF) process. For milling, a CAD design was converted into a 3D model. For this, a conical shape of 3D modeling was made in fusion 360. After onwards, it was simulated for finding the maximum depth for the cracking point. Next for the experimental part, the maximum forming depth was considered, and used lubricant grease for reducing friction. While forming with the grease, the impact of parameters was also changed. Throughout the process, an optimization approach was set to reduce the cracking areas for the G-code. Along with the lubricant use, smooth milling finished surface was observed. To reducing the depth forming errors, an optimization approach was introduced in this research.

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/

Investigations of tribological performance of slewing bearing raceway with bionic textured composite surface under grease lubrication

To improve the insufficient lubrication of slewing bearing, this study investigates the tribological properties of 42CrMo bionic textured composite surface (BTCS) with different densities under MXenes-Ti3C2 lithium composite grease (MLCG). Inspired by the micro-texture characteristics of the clamshell, BTCS is composed of 42CrMo and Sn-Ag-Cu (SAC) alloy. The results indicate that the tribological performance of BTCS (ρ = 38%) is improved most significantly, the average friction coefficient (0.056) and wear rate (6.4 ×10−8 mm3N−1m−1) of the counterpart ball reach the minimum, and the worn surface is fine and smooth. This is mainly attributed to the synergistic self-repairing effect of MXenes-Ti3C2 and SAC on the worn surface. Furthermore, SAC particles act as submicron rolling bearings, transforming the friction form into rolling-sliding.

Influence of Dynamic Viscosity of a Lubricant Material on the Parameters of Adhesion Bond in the Systems of Materials "12KH2H4 - STEEL 45", "45KHN2MFA - Steel 45" when Boring and Borocement Steel 45

In this work, the regularities of the change in the shear strength of the adhesive bond τ0 and the piezoelectric coefficient β in the metal systems "12Kh2N4 (45KhN2MFA) - steel 45 + B", "12Kh2N4 (45KhN2MFA) - steel 45 + VS" were obtained during physical modeling of the shear of surfaces of small-sized samples and changes in dynamic viscosity environment of their interaction with the use of additional equipment of the SMTs-2 friction machine. It has been established that borating and boron carburizing of the surface of steel 45 leads to the absence of adhesion to the surfaces of steels 12Kh2N4 and 45KhN2MFA in certain ranges of normal pressures, at which τ0> 0 and the dynamic viscosity of liquid and grease. It was found that the parameter τ0 when lubricating surfaces is determined to a greater extent for the system "12X2H4 - steel 45", and partially for borating steel 45 and low values of dynamic viscosity μ = 0.027 Pa•s. With an increase in the dynamic viscosity of the liquid phase of the lubricant in the "12X2H4 - steel 45" system, there is a tendency to an increase in the value of τ0. It was found that the absence of modification of steel 45 with boron and boron carbide predetermines the independence of the piezoelectric coefficient from the viscosity of the liquid lubricant and the shear rate. Boring and boron carburizing steel 45 predetermines an increase in the piezoelectric coefficient by an average of 1.6 times with an increase in dynamic viscosity from 0.027 Pa•s to 0.19 Pa•s at a shear rate of 10.16±0.8. At shear rate = 5.08±0.6 mm/s, the piezoelectric coefficient is relatively constant in the systems under study. With the transition to contact through a grease lubricant, there is an ambiguous manifestation of the rate of change of the piezoelectric coefficient.

Numerical and experimental study of elastohydrodynamic grease lubrication of dimple textured surfaces

Numerical and experimental study of elastohydrodynamic grease lubrication of dimple textured surfaces

YNAMIC VISCOSITY OF THE LUBRICANT AND ITS EFFECT ON STEEL MATERIALS WITH BORON

In this work, the regularities of the change in the shear strength of the adhesive bond τ0and the piezoelectric coefficient β in the metal systems "12Kh2N4 (45KhN2MFA) -steel 45 + B", "12Kh2N4 (45KhN2MFA) -steel 45 + VS" were obtained during physical modeling of the shear of surfaces of small-sized samples and changes in dynamic viscosity environment of their interaction with the use of additional equipment of the SMTs-2 friction machine. It has been established that boridingand boron carburizing of the surface of steel 45 leads to the absence of adhesion to the surfaces of steels 12Kh2N4 and 45KhN2MFA in certain ranges of normal pressures, at which τ0> 0 and the dynamic viscosity of liquid and grease. It was found that the parameter τ0when lubricating surfaces is determined to a greater extent for the system "12X2H4 -steel 45", and partially for borating steel 45 and low values of dynamic viscosity μ = 0.027 Pa•s. With an increase in the dynamic viscosity of the liquid phase of the lubricant in the "12X2H4 -steel 45" system, there is a tendency to an increase inthe value of τ0. It was found that the absence of modification of steel 45 with boron and boron carbide predetermines the independence of the piezoelectric coefficient from the viscosity of the liquid lubricant and the shear rate. Вoridingand boron carburizing steel 45 predetermines an increase in the piezoelectric coefficient by an average of 1.6 times with an increase in dynamic viscosity from 0.027 Pa•s to 0.19 Pa•s at a shear rate of 10.16±0.8. At shear rate = 5.08±0.6 mm/s, the piezoelectric coefficient is relatively constant in the systems under study. With the transition to contact through a grease lubricant, there is an ambiguous manifestation of the rate of change of the piezoelectric coefficient

Oil-bleeding dynamic model to predict permeability characteristics of lubricating grease

For grease lubrication, the dominating mechanism supplying new oil to the lubricated contact is assumed to be “oil bleeding” in which the key parameter is the grease permeability. This paper proposes a dynamic oil bleeding model based on a static oil bleeding apparatus. This model uses a permeability correlation that has been adapted to consider the effect of temperature. Grease is described as a porous network of thickener fibres that contains the oil which bleeds out when it is compressed. This system was described by mass and momentum balance equations. The resulting dynamic simulation and the experimental results were compared to obtain the permeability value by using a parametric estimation method. Results are consistent with those found in the literature.

Lubrication of Radial Loaded Tapered Roller Bearings Under High Rotational Speeds

To improve the manufacturing accuracy in the machining process, the stiffness of the machine tool spindle must be increased. One approach is to replace the conventionally used spindle bearings by tapered roller bearings to achieve a higher stiffness and load carrying capacity. However, the speed capability of this bearing type is limited, though can be enhanced by sufficient lubrication, especially in the critically loaded rib-roller-contact. The objective of this paper is to validate the lubricant influence on the speed capability of radially loaded tapered roller bearings. In various speed step runs, the operating behavior of the bearings under oil-air and grease lubrication was evaluated based on the outer ring temperature and the vibration level in the test rig. With oil-air lubrication, a speed parameter up to 900,000 mm/min could be achieved, whereas with grease lubrication, a speed parameter of 540,000 mm/min could be reached. In comparison, the setup with spindle bearings can achieve the highest investigated speed parameter of 900,000 mm/min with both grease and oil-air lubrication. For grease lubricated ball bearings, significantly higher temperature fluctuations are present with variation of the radial load. In the case of oil-air lubrication, the steady-state temperature improved with increasing oil viscosity.

Principle Analysis and Fault Handling of MCC400A Electric Wheel Automatic Lubrication Control System

Selecting the appropriate lubricating grease, applying the right amount of lubrication, suitable intervals, and the correct lubrication points can significantly reduce equipment maintenance and spare parts costs, while enhance the reliability of equipment operation. A well-functioning automatic lubrication system for mining dump trucks can greatly minimize friction and wear, thus extending the lifespan of bearings and mechanical components. Through in-depth analysis of the principles of the MCC400A electric wheel automatic lubrication control system and combined with on-site troubleshooting processes, we have accumulated valuable maintenance experience. This experience holds great significance for maintenance personnel to master troubleshooting techniques for automatic lubrication control systems. By understanding the system principles and analyzing the root causes of issues, we can precisely locate and resolve faults. Additionally, by leveraging modern technology effectively, we can enhance system stability and reliability, further improving equipment operational efficiency. In conclusion, optimized lubrication practices and a thorough understanding of the system will contribute significantly to the sustainable operation of equipment and reduced maintenance costs.

The lubrication mechanism behind the transition from churning to bleeding in grease lubricated bearings – Experimental characterization

Grease lubrication mechanism can be divided into two distinct phases: the churning phase and the bleeding phase. Grease churning starts when the bearing operation starts, and bleeding commences at the end of churning. During the churning phase, the friction torque and the bearing/grease temperature are very high. At the end of churning, the temperature drops to a steady state. The transition from churning to bleeding is not well established. In this investigation, we performed bearing experiments and rheological studies to understand the transition phenomenon. The results show that the churning-to-bleeding transition ends when grease becomes uniform in the bearing. We also present an experimental method based on degradation and rheology to identify the churning behavior type.

An Analysis of the Process of Applying Technical Lubricating Coatings

The results of research on the process of applying lubricating coatings are presented in this work. For this purpose, plastic greases were used, in which the base oil is perfluoropolyether (PFPE) and the thickener is poly(tetrafluoroethylene) (PTFE). Due to their consistency, these materials are classified into different classes according to the National Lubricating Grease Institute (NLGI). The research was carried out using a time-pressure valve at varying atomization pressure values. Based on the obtained results, the width of the obtained material path and the angle of spray atomization were determined. The research indicated linear relationships between the atomization pressure and the degree of uniformity of the obtained spray.

Numerical and Experimental Study of Elastohydrodynamic Grease Lubrication of Surfaces with Longitudinal and Transverse Pattern

The interaction of non-Newtonian grease with patterned surfaces was considered as a promising approach to find an effective method for reducing friction and wear in rolling contacts. Longitudinal and transverse patterns can retain the lubricant in the contact area and prevent it from escaping under high loads. In this paper, a model has been developed for grease elastohydrodynamic lubrication of surfaces with different patterns to estimate the lubrication parameters such as lubricant film thickness, pressure distribution, and viscous friction. Then several experimental tests are rolled out for different loads, velocities, and surface patterns. Because the friction model estimates only viscous friction, a correlation is recommended for considering the friction due to asperity interaction. This relation is based on average lubricant film thickness results which are calculated from the model. The calculated friction and experimental results have a good agreement. According to the experimental tests, transverse, longitudinal, and isotropic pattern had a lower friction coefficient, respectively. While the isotropic viscous friction coefficient estimated by the model is lower than others. Higher loads and lower velocities cause a higher friction coefficient in all surface patterns.

Effect of the grease thickener on tribological properties of Si3N4/GCr15 contact interface and the performance in hybrid ceramic ball bearing

Si3N4 hybrid bearings are considered the most promising motor bearings due to their characteristics of electrical insulation, high speed, low friction coefficient, and wear resistance, which can better meet the requirements of driving motors of electric vehicles. However, the tribological mechanism between the ceramic-grease-steel complex interface is unclear. Three kinds of greases, namely lithium, polyurea, and calcium sulfonate complex grease, were synthesized from poly alpha olefin 40 as base oil. The effects of grease thickener morphology on the tribological properties of Si3N4/GCr15 contact surfaces at different slip speeds were investigated, and the vibration and friction torque performances in 6204 hybrid ceramic balls were evaluated. The results showed that the thickener could form physical deposition film and friction film to protect the worn surface at low speed. The friction and wear conditions were significantly improved at high speed under lithium grease and polyurea grease lubrication, being a mixed lubrication state. In presence of lithium grease, the tribological performance of the Si3N4/GCr15 interface and the vibration performance, impacted condition, starting torque, and friction torque of the hybrid ceramic ball bearings were all the best. Because lithium grease is subjected to continuous shear of the ceramic ball, which releases the base oil stably, and forms a thick oil film with the broken thickener in the center of the raceway, the bearing is in a mild lubrication state. Therefore, for Si3N4 hybrid ceramic ball bearings, lithium grease is a lubricant with good application prospects.

Reduced Friction and Excellent Anti-Wear Performance of QBe2 Beryllium Bronze against 38CrMoAlA Steel in Pneumatic Downhole Motor under Grease Lubrication

To improve the service life of the newly designed pneumatic downhole motor, a kind of commercially available lithium complex grease was used to help avoid the rapid wear-induced failure of the dynamic seal of pneumatic downhole tools in operation. The investigation on the tribological behaviors of QBe2 beryllium bronze and 38CrMoAlA steel tribo-pairs in pneumatic downhole motor revealed that under lubrication, the instantaneous friction coefficient and wear volume became very low, showing greatly reduced friction and excellent anti-wear performance. Compared with the case without lubrication, the adhesive wear mechanism and ploughing effect of the tribo-pairs were significantly alleviated. Moreover, Cu and Fe were oxidized to form composite oxides between the frictional surface, further improving the lubrication effect between the QBe2 beryllium bronze and 38CrMoAlA steel. Notably, the test could be operated stably for more than 150 h under lubrication, fully reaching the requirement of pneumatic downhole tools under actual drilling conditions. These results provide a solid support for the practical application of the reported pneumatic downhole tools.

Tribological Failure Analysis of Journal Bearings used in Sugar Mill

Sugar factory uses the sugar mills for the extraction of juice from the cane for the further processing. The size of the sugar mill will vary from the capacity of sugar factory either 2500TCD or 5000 TCD. These sugar mills are supported by using the journal bearings because of the heavy loads. After doing the survey at various sugar industry named as Sanjivani Sugar Factory, Kopargaon Sugar Factory Kolpewadi, Madha Sugar Factory etc, it is observed that they are facing the problem of frequent failure of the journal bearing liners. The present study provides the effective solution for the increasing the life of the liner with the modified polymer composites materials. The failure causes of bearings are identified by simulating the operating conditions and conducting measured experiments on a Journal Bearing setup with requirements for different combination (i.e. load, lubricating oil, and speed) of operating conditions. The DOE technique is used to predict the performance of bearing [1,3,7]. The experimental and theoretical results show the presence of boundary lubrication conditions in sugar mill journal bearings. To diminish the problem of relatively high wear, grease lubrication with special additives should be used for the application [11].

Trends in Grease Lubrication for Rolling Bearings for Automotive Electrification

Trends in Grease Lubrication for Rolling Bearings for Automotive Electrification

Исследования износостойкости и антифрикционных свойств металлополимерных пар, работающих в имитаторе морской воды

Introduction. Sea water is an aggressive environment that causes corrosion, erosion, and cavitation when moving at high speeds of steel, cast iron, bronze, or babbit parts that work satisfactorily only with lubrication. In this case, oil stains are often released into the water, which leads to pollution of the water basin. Materials and methods. To study the wear and friction coefficient, the following materials were chosen: pure polyamide P-610 and antifriction materials based on it Maslyanit D and Maslyanit 12. The following metals were used as the material of the counterbody: stainless steel Cr18Ni9Ti, bronze (9 % Al; 2 % Mn), and titanium alloy VT-3. Results and discussion. It is established that the materials of the “maslyanit” group have significantly better wear resistance and antifriction properties than pure polyamide P-610. It is shown that the reason for such properties of Maslyanit D and Maslyanit 12 is the presence of solid and grease lubricants in its compositions, which simultaneously also play the role of a plasticizer. Finely dispersed metal fillers favorably affect the heat rejection from the friction zone and the growth of the crystalline phase of the polymer. A positive effect of iron minium on the friction of Maslyanit 12, which causes the generation of a protective anti-friction film on the working surfaces of the friction pair, is revealed. A decrease in wear and friction coefficient is found as the purity class of the metal surface increased. The predominantly fatigue mechanism of wear of polymeric materials during friction in a sea water simulator is confirmed. The results of testing Maslyanite 12 in a real marine environment confirmed the positive characteristics of Maslyanit 12.

Mechanical and Three Body Abrasive Wear Behaviour of Nano-Filler Filled, Chopped Glass Fiber Filled Hybrid Composites

Polymer matrix composites are developed for tribological applications due to the possibility of optimizing the properties with the addition of special filler materials as reinforcement. Filler filled polymer matrix composite systems are used in many automotive parts and components like brake pads or clutches which require high coefficient of friction coupled with low wear. However, in most cases it is the primary concern to develop polymer composites that posses low friction and low wear properties under dry sliding conditions against smooth metallic counterparts e.g., gears or bearings, chute liners and coal handling equipments in power plants, gear pumps handling industrial fluids, agricultural machine components. Polymer composites operate in applications where fluid and grease lubricants fail, and have superior tribological performance to traditional polymer composites. Particulate fillers or fibres or solid lubricants have been a part of notable reductions in the wear rate of the polymer matrix at very low loading, and there exists a wide scope on the development of polymer composites on the tribological behaviour. The incorporation of fillers in polymer could provide a synergism in terms of improving mechanical properties and wear performance, which has not been adequately explored so far. The research on nano fillers such as nano clay, Glass fiber and Titanium di-oxide (TiO2) in epoxy system is scarcely reported and further they focus on a few specific issues only. The present study was focused on investigating Mechanical - Tensile, Hardness, and three body abrasive wear characteristics of thermosetting based Epoxy composites and the effect of incorporation of nano clay, TiO2 nanoparticles and chopped glass fiber on microstructure, hardness, friction and abrasive wear are determined and analyzed. The main aim was to investigate the effect of applied load, sliding distance /abrading distance, sliding speed and percentage of filler. The surface morphology of the worn out surfaces were examined using SEM, to get a better understanding of the wear mechanisms.

MoS2-functionalized attapulgite hybrid toward high-performance thickener of lubricating grease

An important prerequisite for developing high-performance industrial lubricating grease is to regulate the composition and structure of thickener for obtaining lubrication function. Herein, MoS2-grafted attapulgite (ATP) hybrid as grease thickener was prepared by one-step hydrothermal method. The polarizable Mo atoms were coupled with the tetrahedral structure of ATP matrix to yield MoS2-functionalized ATP (ATP/MoS2) hybrid. The regulated-grease using ATP/MoS2 as thickener in poly-alpha-olefin (PAO40) oil significantly reduces the friction (31.5%) and wear (37.5%) due to the synergy of as-prepared ATP/MoS2 thickener with superior thickening and lubrication function. The achievement of superior tribological properties mainly depends on the interlayer slip of even-distributed MoS2 and tribo-chemical film. MoS2-functionalized ATP might guide the development of a novel nano-thickener for high-performance lubricating grease.

A practical Approach to predict Service Life and Re-lubrication Rate of Grease in Rolling Bearings

Lubrication is crucial for a sustainable operation of any machinery. A sustainable application of lubricants requires the avoidance of any waste, lubricants should not be exchanged long before their service life has ended. This refers especially to those applications where high operation temperatures are reducing the service life and require a huge consumption of lubricants. Therefore, to fulfil the requirement of sustainability a prediction of the service life at elevated temperatures is crucial. At elevated temperatures the service life of lubricants is limited by thermal aging. This results from a chemical reaction of components of the grease with the oxygen of the ambient air. Such a process follows the Arrhenius equation of chemical kinetics and is given by a straight line in a so-called Arrhenius plot. The slope of the line in the Arrhenius plot is given by the activation energy EA. The FAG FE9 test run is a typical method to assess the service life of a lubricating grease in bearings at elevated temperatures. The test is performed at the upper temperature limit of the grease and gives the service life at this maximum temperature. Once the activation energy EA is available the service life at any other temperature may be calculated. Since the temperature of Abstract *Frank Reichmann CARL BECHEM GMBH, Hagen, Germany the FE9 test run is usually the upper temperature limit the operation temperature is usually lower. Once the calculation start from a high temperature in direction a lower temperature low figures of activation energy EA are resulting in conservative service lives, as it is displayed in in this paper. In case of high figures of the activation energy EA the calculated service life becomes too high what may result in bearing failures. With FE9 test runs at different temperatures an activation energy EA = 75 kJ/mol was found for a reference grease. Laboratory methods to determine the activation energy do usually result is much higher figures. For example, HP-DSC test with this reference grease resulted in an activation energy EA > 100 kJ/mol, mostly it was even EA > 120 kJ/mol. Such a result will lead to unrealistic high calculated service lives. An activation energy of EA = 75 kJ/mol is basically a proper assumption for the calculation of service life of most greases. Generally it is always recommended to estimate a low activation energy.