Four Ball Wear Test Methods for Lubricants

It is imperative to emphasize the wear-reducing and load-sustaining abilities of the lubricating oils, as they are an essential part of their operation. In this study, the anti-wear and extreme pressure (EP) performance of Jatropha oil was explored. The investigation was executed on a 4-ball tester machine according to ASTM-D-4172 and D-2783 standards. Nano-sized Molybdenum disulfide and graphene were added to the base oil, whose addition reduced the wear on the test balls but failed to improve the EP properties. However, the addition of Garlic oil elevated the EP properties of the base oil. The Last Non-seizure load and weld point of the jatropha oil was elevated by up to 3 levels, while the Load Wear index was increased by 91.88%. The Flash Temperature Parameter of jatropha oil was increased by 658% and 250% at 100kgf and 126kgf load, respectively, after the addition of 5% garlic oil. Further, the wear scars were examined under an optical microscope and FESEM, which proved that the addition of nano-additives reduced the wear of the balls during anti-wear tests at lower loads, and g... Read More

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Fretting wear is a phenomenon occurring in many engineering objects, including push fit connections. In view of a large number of factors conducive to wear development, it is difficult to describe the mechanism of wear initiation and development. Therefore, various methods are sought to limit wear development. The use of a lubricant may be one of those ways. The aim of this article is to present the results of testing the influence of a lubricant medium on the development of fretting wear in interference fit connections. As a lubricant medium, MoS2 and Whitmore greases were used. For that purpose, wear tests were first conducted on the shaft/sleeve tribological kinematic pair, and then observations and laboratory measurements were performed. The observations demonstrated the presence of fretting wear traces on all tested samples, irrespective of the tribological kinematic pair being tested. The main kind of damage consisted of material build-ups which, during operation, become oxidised and, while moving along the connection, caused local abrasion and micropits. The best results in re... Read More

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A testing apparatus for friction and wear in rotary apparatuses, comprising a testing mechanism, controller, lubrication system, cooling system, loading system, and detection system. The testing mechanism simulates operating conditions of high speed, temperature, and load, while the controller coordinates the systems to maintain stability and reliability. The lubrication system delivers lubrication medium to the testing mechanism, the cooling system maintains temperature control, the loading system applies axial load, and the detection system monitors performance parameters.

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Abstract The bearing cage played a pivotal role in affecting the lubricant redistribution and lubrication states. In this study, a cage unit is incorporated into an optical ball-on-disc apparatus for the purpose of a quantitative study of cage-induced lubrication phenomena. It is found that the presence of the lubricant layer on the ball surface, shaped by the cage, affects the inlet lubricant supply of contact between the ball and the glass disc. Thereafter, the oil reservoirs surrounding the contact area and the film thickness were measured. The results showed that the lubricant reservoirs and inlet lubricant supplement were significantly improved with the employment of the cages. In addition, the lubrication state transformed from starved to fully flooded, effectively enhancing the lubrication state. Moreover, the lubricant on the steel ball surface moved from the side bands to the central rolling track, indicating that the lubricant redistribution was the main reason for the lubricating enhancement. Notably, the groove modification on the inner surface of the cage pocket facilita... Read More

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Deep-groove ball bearings for the eAxles of electric vehicles must adapt to higher rotational speed conditions because the speed of eAxle motors have been increasing as the size and weight of the motors decrease. Therefore, understanding the oil-lubricated conditions inside ball bearings at high rotational speeds is essential for optimizing their design for eAxles. To clarify the oil-lubricated conditions inside ball bearings at these high speeds, a new test apparatus was developed. This apparatus is capable of simultaneously measuring the friction torque of deep-groove ball bearings, the oil-film thickness on the rolling balls, and observing the oil distributions inside the bearings at rotational speeds up to 20,000 min -1 . The oil-film thickness was measured using three-wavelength optical interferometry, and the oil distribution was observed using fluorescence. It was found that the oil-film thickness became constant at rotational speed conditions exceeding approximately 7,700 min -1 . Oil starvations were observed on the raceway around the rolling ball, and these regions increase... Read More

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Lubricating grease plays an important role in the rolling screw transmission of the actuation system and is particularly concerned with the performance stability of long-term storage in aerospace applications. In this article, a batch of ball screws that were lying flat in the warehouse for about eight years were selected to extract lubricating grease from the screw raceway after being stored in situ. The oxidation performance, friction performance and rheological properties of lubricating grease were tested and compared to those of fresh grease to analyze and summarize the performance changes in lubricating grease. The transmission efficiency, friction torque, and temperature rise of ball screws without removing the original grease and those filled with fresh grease after cleaning were tested and compared. The impact of grease degradation on the transmission performance of ball screws was analyzed to provide a reference for ball screw lubrication schemes and further accelerated storage experimental design.

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The performance and endurance of lubricating greases is often assessed through model tests (like four-ball tests or SRV tests). This approach has some limitations, especially when greases with special fillers are investigated, because simplified laboratory test conditions can never replicate real operating conditions. For a more reliable assessment on the performance of a lubricating grease, lubricants must be tested in close-to-actual operational conditions, e.g. through component tests. This paper presents both the design and implementation of a dedicated test rig to test lubricating greases through middle-sized thrust ball bearings. The test rig design is optimized to monitor the effectiveness of lubrication and determine the useful life of grease by recording representative parameters, namely bearing temperature at different location in the bearing, vibration level, and electric contact resistance (ECR) through the bearing. The results of a couple of assessment tests are presented and confirm that the test rig is working as expected. The chart of the parameters being monitored sh... Read More

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The article presents the results of tribological and rheological research of lubricating composition modified of various content of titanium dioxide. The analysis of anti-wear properties during the test for the tested lubricating composition indicates a significant change in this parameters for lubricants modified of titanium dioxide. A change of the value of evaluated tribological parameters leads to change in the structure of the composition carried out tests and a change in the effectiveness of the tribological protection of the tribosystem. The content of the thickener, base of oil and additive in the lubricant structure affects the level of the anti-wear properties, as evidenced by the results obtained during the tribological tests presented in this article. Also, the tribological tests were carried out with the T-02 four-ball machine for the base grease, i.e. without a modifying additive, and compared with the results obtained for lubricating greases modified with various amounts of titanium dioxide. The results of welding load, limiting pressure of seizure, scuffing load, limi... Read More

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In tribology, maintaining good lubrication of friction pairs is an important technical means to reduce wear and failure, which is very important but difficult to monitor the lubrication state of friction pairs. In this paper, when measuring the thickness and shape of the lubricating oil film by the ball-disk elastohydrodynamic oil film measuring instrument, a current amplifier is integrated to measure the electrical signal generated during the friction process. By monitoring the change of lubricating oil film, the change of ball-disk friction force, and the change of triboelectric signal during the friction process in real time, the relationship between the tribological behavior and the triboelectric behavior of the friction pair is explored. The experimental results show that under the conditions of limited oil supply, different rotational speeds and different lubricating oil viscosities, the time of the discharge phenomenon of the steel ball corresponds one-to-one with the time when the friction pair starts to wear under oil-scarce lubrication. The discharge occurs due to the elect... Read More

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Wheel bearings play a crucial role in ensuring the smooth and reliable rotation of wheels in automotive applications. Grease is commonly used as a lubricant in wheel bearings. The physical properties of grease, such as viscosity, base oil type, and thickener composition, significantly influence the overall performance and longevity of wheel bearings. This study investigates the impact of grease's physical properties on wheel bearing friction torque and service life. To evaluate the effects of different grease formulations, a series of experiments were conducted using a four-ball tester, rheometer, and a custom-built test rig to measure bearing frictional torque and service life. Multiple greases with varying viscosity grades, base oil types (mineral oil, synthetic oil), and thickener compositions (lithium, diurea, and polyurea) were tested under controlled operating conditions. Friction torque measurements were obtained using a high-accuracy torque sensor, while service life was determined by monitoring the bearing life in actual endurance testing. The results indicated that grease p... Read More

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This chapter focuses on presenting and discussing some of the emerging tribological test methods and machines capable of quickly evaluating lubricants and materials under electrified contact conditions that are very typical of the shaft current/voltages encountered in actual electric vehicles drivelines. To provide a better understanding of the specific operation and application conditions of such methodologies and testers, we describe two specific case studies. These cases (i.e., pin-on-disk and four-ball test configurations) crudely correspond to the tribological evaluations of lubricants and materials used in bearings and gear systems operating under electrified conditions. Overall, this chapter exemplifies how contact electrification can influence the tribological behavior of driveline materials and lubricants. The knowledge gained could be very useful in understanding the underlying friction and wear mechanisms, which will be very important for the optimization of such materials and lubricants for higher efficiency and reliability of future EVs.

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The ball bearings used to support the shaft of LNG pumps are nonstandard bearings. The bearings operate in the cryogenic environment(-162C) and they are a type of self-lubricated ball bearing using solid lubricant and have larger internal clearance grade than general standard bearings. The defect in ball bearings is the most common failure cause of LNG pumps. In order to ensure the stable operation of LNG pumps, it is important to optimize the design of bearings with the performance evaluation test and reliability test that ensure fatigue life is also needed. In this paper, the tribo-test apparatus was developed for the performance test and reliability test. This test apparatus is designed to evaluate the performance by measuring friction torque and cage orbit of test bearings. Prior to the perform the ball bearing test, the verification test of the test apparatus was done by operating for about 4 hours with the LN2(-189C) submerged chamber. The stability of the rotor system(motor to shaft) was monitored with the motor input current. The relation between motor input current and tor... Read More

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The paper objective is to test the developed lubricoolants of domestic production for broaching operations instead of imported analogues. The results of comparative laboratory tests of new technological lubricoolants Rosoil-V9 and Rosoil-423M for broaching operations, which are analogues of imported coolant, are presented. Laboratory tests are carried out in the Laboratory for Testing Technological Lubricants of Self-supporting Creative Center of Ufa Aviation Institute. Tribo-engineering properties are determined on a four-ball friction machine according to GOST 9490-75; cooling characteristics are determined on UZS-2 installation. The physicochemical properties are evaluated by standard test methods. As a result of the conducted research, it is found out that the physicochemical properties of Rosoil lubricoolants are similar to imported ones, and in terms of tribo-engineering and cooling characteristics, Rosoil lubricoolants are better than imported analogues.

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Based on the analysis of standards for the testing of lubricants, both liquid and plastic, on a four-ball tribometer, and the analysis of the parameters by which lubricants are evaluated, this paper proposes a methodology and an integral parameter for the estimation of tribological properties. The methodological approach proposed in this paper allows for the integration of a variety of parameters provided in the standards for the testing of lubricants into one indicator. Herein, we show that the developed technique is based on the energy approach and takes into account the specific wear work of the test material (steel balls) in the lubricating medium to be investigated. The results of laboratory tests of a wide range of lubricants are presented: hydraulic fluids, motor and transmission oils of various purposes and classifications. It is shown that the magnitude of the integral parameter can be used to assess the effectiveness of anti-wear and anti-scuff additives in base lubricants, as well as the ranges of their applications. This allows for differentiation and quantitative evaluat... Read More

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This paper introduces a modified ball-on-disk test, utilizing a drilling machine, to investigate the tribological behavior of wear on a plate surface under various lubrication conditions. The tribometer, based on the ball-on-disc principle, employs an improvised bench-top drill press machine. Despite its simplicity, it effectively facilitates wear-track experiments using engine oil (SAE 15W 40) and palm oil as lubricants. Tests are conducted at room temperature, maintaining a constant load at 8.83 N and rotational speed of 180 rpm for 2 minutes per sample. Microscopic analysis of wear scars on the plate samples reveals distinct wear patterns and characteristics for each lubricant, with measurements taken at multiple positions for accuracy. The current work focuses exclusively on wear scar analysis, with findings indicating that engine oil outperforms the counterpart, displaying a smaller wear track width, hence superior lubrication and wear protection capabilities. In contrast, palm oil exhibits a larger wear track, implying limitations in friction reduction and material preservation... Read More

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Eco-friendly lubricant research continues to increase since it has a comparative performance to commercial mineral lubricants to overcome the effects of environmental impact. However, the efficiency of these green lubricants depends on specific applications. In this study, we analyzed the friction and wear performance of a castor/sesame oil mixture as an eco-friendly lubricant and its comparison to a commercial mineral lubricant tested in a metallic system employed in bearing elements. For this purpose, AISI 8620 steel against ISO 100Cr6 was used as tribological pair. The friction and wear tests were carried out through a Tribometer of ball-on-disk configuration under boundary lubricating conditions, whereas the worn surfaces were investigated by using optical and electron microscopy. The physical properties and the rheological properties of the lubricants were also determined. The friction and wear performance between the eco-friendly lubricant and mineral oil were similar so that the CLE were comparable. The CLE values in terms of friction and wear ranged from 86% to 99.4%, respect... Read More

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Proper lubrication regime in engines significantly impacts engine performance, fuel efficiency, durability, and environment. Lubrication regimes reduce friction between engine components, control wear, and ensure long-lasting parts. This study conducted experiments on a wear-testing device to determine the amount of wear between the piston ring and cylinder pair. The experimental work was performed at different loads and speeds. The tribological properties of 0W20 and 10W40 lubricating oils were examined in the study. As a result of the experimental work, when using 10W40 lubricating oil in the wear testing device, lower cylinder wear was observed compared to using 0W20 lubricating oil. The study found that the amount of wear increases as the load on the cylinder sample increases. The maximum cylinder wear was obtained under an 80N load. The minimum cylinder wear was determined under a 40N load. SEM images of the cylinder samples were also examined to determine the damage after wear.

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The ability of lubricants to prevent surface damage and wear is critical in various industrial applications.This study presents an evaluation of the anti-wear performance of some industrial lubricating oils (A, B, and C) with working conditions according to ASTM standards.The results show that oil A has better anti-wear performance than oil B and C under the same working conditions.Oil A also showed stable characteristics during the testing process, with minimal weight differences and scratch widths of the test ball before and after the experiment.In addition, other specifications such as viscosity, viscosity index, pour point, and flash point do not significantly affect the wear resistance of the lubricating oil under these operating conditions.This research highlighted the importance of selecting the right lubricant to minimize wear surface damage, contributing to the performance and longevity of machine components.

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Lubricant has an important function in protecting the parts of an engine where to minimise the wear formation on the surface between two moving parts. The mixing of lube oil SAE10W-30 Petronas oil and Shell oil may have caused an effect to the wear stability of the lubricant. The aim of this study is to determine the behaviour of the oils viscosity, COF and WSD of the ball using the FBM. The experiment was done under different speed and the mixture was rested. Based on the analysis, the viscosity is thinning as the temperature gets high. The thinnest oil is 20% Shell mixture and 5% Shell is the thickest but viscosity was not affected by the rested time. COF has decreased as the speed increased. However, longer resting period did not give any effect as the speed higher but has increased COF. The WSD was increased by the higher concentration of Shell as well as the speed. Overall, different concentration of Shell oil and rested time has an effect on the lubricity performance.

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Pin-On-Disc is a tool used to test a material's friction and wear levels. This tool is also one of the tribometer components. Pin-on-Disc uses a ball-shaped pin and a disk of ST 60 wrought iron as a disc in this test. This test aims to see or determine the volume of wear produced by pins with SAE40 and SAE140 lubricants and the importance of pin wear without lubrication. Lubrication influences the material or test specimen in this tribometer test. In this test, they are using a simple Pin-on-Disc Tribometer. The results obtained from this test are that the test without using lubricant shows at coordinates 0.0704 N, while the test with SAE40 lubricant shows at coordinates 0.07027 N, and testing with SAE140 lubricant is at coordinates 0.0703N.

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Theoretical studies on the influence of the properties of magnetic liquid lubricants in the hydrodynamic rolling system have been documented. These studies have shown that the bearing lubricated with magnetic fluid enhances the load-carrying capacity, damping and stiffness and reduces the friction force and side leakages compared to the conventional lubricating oil. Tribological properties, namely anti-friction, anti-wear and weld load of all samples, are evaluated using a four-ball test machine. Before each test, new steel balls were ultra-sonicated for 5 min in acetone and wiped using a fresh and lint-free industrial wipe. The steel balls were placed into the ball pot assembly by lifting a ball race and were tightened using a torque wrench (68 N-m) to prevent the motion of three balls during the experiment. In order to understand the tribological properties of nano lubricants, it is essential to understand the properties of the basic oils used to synthesize magnetic fluids.

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Lubricants are essential for keeping internal combustion engine parts lubricated and extending the engine's useful life.For its application, lubricating oils' load carrying capacity is a crucial factor.This study measures the coefficient of friction of 20W40 engine oil with various nanoparticles using the Four-Ball testing method.The tribological characteristics of the formed oil were assessed by a four ball tester during tests that were conducted in accordance with conventional test procedures.For 30 minutes, the spinning ball is rotated at 1,200 rpm at 75 C.As per ASTM D 4172 B, the coefficient of friction was assessed.

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This study investigated the effectiveness of lubricants and additives in preventing surface damage and wear, which is critical for numerous industrial applications. The ASTM standard operation conditions were employed for a series of experiments using a four-ball friction and wear tester, testing three different oils (A, B, and C) with and without 0.5% fly ash additive. The experiments were analyzed using a microscope to evaluate the effectiveness of oils and additives in preventing surface damage. The study found that certain anti-wear additives significantly reduced the size of wear scars on the balls, indicating their effectiveness in reducing surface damage. These findings have important implications for developing new lubricant formulations and optimizing industrial processes that involve sliding and rolling contacts. The study emphasizes the importance of selecting appropriate oils and additives for specific applications to minimize surface damage and wear, which is crucial for improving the performance and lifespan of machine components.

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Abstract: We have an increasing global need for bio lubricants that are safe for human and environmental use, easily biodegradable, and non-polluting. The friction and wear qualities of cotton seed blended lubricant as well as castor blended lubricant are compared and contrasted in this research using a Pin on disc wear testing Tribometer. In this research, we will look at the study's results and analyse their significance. Blended lubricants were created by combining cotton seed & castor based biodiesel with the basic lubricant SAE20W40 at volumetric ratios of 5, 10, 15, & 20%. Cotton seed and castor blended bio lubricants were tested for friction and wear at sliding velocities of 2.5 metres per second while subjected to weights of 50 N, 100 N, and 150 N. Wear might be slowed by as much as 15 percent by mixing in cotton seed biodiesel with the base oil, as has been shown. When this threshold is passed, wear increases at an ever-increasing pace. Castor oil blended lubricant performed best in wear tests when coupled with a base lubricant at a 5 and 10 percent castor oil blende... Read More

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The impact of lubricating oil degradation, which can happen during both storage and use, on spur gear wear is thoroughly examined in this paper at all scales, from macro to nano. A thorough structure was created by combining the results of testing performed at the macroscale on a test rig and at the nanoscale using tools such as FESEM analysis. Using a single-stage spur transmission under two different working conditions (40 Nm, 1200 rpm, 198 h and 50 Nm, 500 rpm, 90 min), macroscale experiments were carried out using both conventional and artificially degraded lubricant oils. Aqueous hydrochloric acid (36.46% v/v concentration) was added to the lubricating lubricant to induce artificial degradation. Wear development and oil degradation were monitored in real time using tools such as metallic wear detritus sensors and oil sensor suites. Offline methods, such as total acid number (TAN) and pH value readings, were used with periodic lubricant oil samples. It was discovered through both online and offline monitoring methods that the spur gear experienced substantial wear in lubrican... Read More

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A reciprocating friction and wear tester based on Lab VIEW was designed and built to preliminarily test the friction and wear characteristics of different materials under different test conditions and lubricant additives. The mechanical structure and measurement, and control system were optimized. It carried out functional test studies. The test shows that the test results obtained by the tester conform to the tribological law, and the operational performance is relatively stable, which meets the needs of preliminary friction and wear test research.

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Oil lubrication is widely adopted in rolling bearings, the characteristics of which affect the oil film formation and friction state, and also the heat generation and dissipation characteristics. However, it is difficult to measure the internal lubrication of rolling bearings in practice, which is of great importance for lubrication and structure design. In this work, one measurement system for lubricant distribution was built and installed on a test rig to obtain original pictures of the lubricant in bearings. Grayscale images were obtained by picture processing to characterize the lubricant distribution, and the image pixels were evaluated for the characterization of lubricant volume. Finally, the measurement of the lubricant distribution in the angular ball bearing was carried out under different lubrication and cage groove conditions, and their influences were investigated. The results show that the lubricant distribution is affected by the oil jet nozzle angle, operating speed, and cage structure. The lubricant capacity among balls and the cage pocket in bearings gradually incre... Read More

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The increasing worldwide demand for hybrid and electric vehicle technology has brought new challenges for the global lubricant industry. The new lubricants for electric vehicles, also called E-fluids or EV-fluids, are expected to meet a new set of requirements including withstanding the much severe operating conditions of EV powertrains. High starting torques, high RPMs and uncontrollable shaft currents passing through the contact interfaces are some of the most challenging powertrain conditions that can impact the performance of these lubricants. Although there have been some papers already reporting on significant alteration of tribological properties of lubricants under electrification, so far there are no standard test protocols aimed at the fast and reliable screening of base oils, additives and formulated lubricants under such conditions. Thus, this research work focuses on exploring the popular four-ball ASTM-D4172 standard method to evaluate the tribological behavior of lubricants under electrified conditions. Specifically, a conventional four-ball tester was instrumented wit... Read More

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The development of new types of lubricants requires highly accurate testing equipment. The design of a laboratory bench has been developed for testing greases according to a four-ball scheme following international standards and beyond them.

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Lubrication is a crucial factor in improving the tribological performance of various components and thus, the overall working performance of an internal combustion engine. This paper addresses the lubrication performance of different lubricants, which are commercially available and used in automobile engines. The experiments are conducted on a four-ball tester for evaluating the tribological performance of selected lubricants, namely SAE20W-50, SAE15W-40, and SAE10W-30. The tests are designed according to ASTM D4172, and the friction and wear performance of the lubricants are characterized for better lubrication performance. The lubricant SAE15W-40 has shown excellent lubrication performance with lower friction coefficient and wear scar diameter among all the tested lubricants.

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Conventional petroleum-based lubricants have numerous environmental and toxic issues related to their disposal. As a result, there is a growing interest in developing innovative environmentally friendly oils as lubricants. A novel apricot oil-based bio-lubricant was developed in the present research work. Its tribological performance was analysed using a four-ball tester compared with SAE 40 oil and blends of SAE 40 and developed bio-lubricant. A four-ball testing method (ASTM D4172) is a test for determining the wear-preventative features of a lubricant. It was observed that the optimum blend of SAE 40 and bio-lubricant had shown better extreme pressure performance than apricot oil-based bio-lubricant and SAE 40 alone.

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Fretting tests on four commercial greases were run on a ball-on-disc machine at 25, 7, 20, 40 C. Post-test wear was measured on the ball and the chemical composition of lubricant films in the wear scar analysed by FTIR (RA-IRS), Raman and SEM-EDS. At 25 and 7 C the greases had similar friction and wear properties. At 20 and 40 C the highest base-oil viscosity grease gave an inferior friction and wear performance. RA-IRS analysis showed thickener remaining in the wear scar for most test conditions. The highest wear was linked to the absence of thickener in the scar. Better wear and friction performance at low temperatures was associated with thickener present in the lubricated contact and lowest base-oil viscosity.

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Increasing interest in utilizing bio-lubricants has been sparked by pollution caused by the mineral oil-based lubricants and their depletion. This study aimed to assess the effectiveness of Jatropha oil based grease as a basis and sodium thickener as an additive. The grease's lubricating abilities were tested using the ASTM 2266 four ball test and molybdenum disulphide as an additive. According to the findings, adding molybdenum disulphide particles decreased wear and the coefficient of friction, with the latter falling by 69% when compared to virgin Jatropha grease. Given that Jatropha grease passed the four ball test, a simulation of real-world conditions, this indicates that it is a reliable lubricant. Wear examinations were performed on steel balls using an optical microscope and scanning electron microscopy, and the results were consistent. It was found that addition of 0.25% MoS2 to virgin Jatropha grease reduced coefficient of friction to 0.12 (69%) from 0.39. Similarly wear scar diameter reduced from 800.583 to 788.44 in presence of 0.25% MoS2 blended grease. The study co... Read More

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Four-ball tribometers are widely used to characterize the efficacy of lubricants in sliding contact. However, the standard apparatus requires 5 mL or more of fluid, which makes characterization of biological fluids such as synovial fluid difficult. Here, we present a four-ball tribometer that requires less than a tenth the sample volume and that is easy to replicate on any rheometer. A steel ball was reversibly attached to a parallel plate rheology geometry, then lowered onto three lower steel balls positioned and stabilized using an additively manufactured holder. Rheometer controls were then used to control axial force and upper ball rotational velocity. The setup was validated on three well-characterized lubricant systems: motor oil, glycerol/water mixtures, and hyaluronic acid. Static and dynamic coefficients of Coulomb friction and wear scar test results were reproducible and consistent with trends from the literature. Simulated healthy and diseased synovial fluid was also characterized to demonstrate the setups utility in measuring lubrication by small volumes of biological ... Read More

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Wear leads to loss of functions of machines and to a decrease in their efficiencies. Controlling wear through wear resistance tests is a very important task. Wear tests aim to obtain wear levels of the elements of assemblies in contact. The profilometric method is very helpful. In this paper, measurements of wear scars using the profilometric method are reviewed. Volumetric wear determinations in various configurations, including ball-on-disc tests, block-on-ring tests, reciprocating ball-on-plate tests, and scratch tests were studied. The measurement of the volumetric wear of balls or rounded pins was also analysed. Possible errors in wear levels determinations were discussed. Limitations of profiloemtric measurement methods were considered.

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Abstract Lubricants are known to change over time, both in terms of aging of the oil and additives, and additive depletion through use. Samples were extracted at intervals from an industrial micro-deep drawing process line to evaluate how the lubricant changes over time. Four-ball testing showed that the tribological performance degraded quickly but stabilised after one million strokes. Measuring of the pH-level and correlation with the oil concentration showed that the emulsion initially becomes more acidic but stabilises after one million strokes, despite changes in oil concentration. Elemental analysis using water inductively coupled plasma (ICP) analysis standard showed that particles in the lubricant could be related to an increasing formation of wear debris. Fourier-transform infrared (FT-IR) analysis was used to evaluate changes in chemical composition of the base oil. Lubricant properties were found to degrade in samples obtained from the onset of the production, while they stabilised for samples that had been in use for a period of more than 1 week. The performance of the us... Read More

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This work proposes a general method for establishing the lubrication analysis model of ball bearing and the oil-air multiphase flow characteristics inside ball bearing is revealed by CFD. Based on the geometric feature, the micro-clearance in the chamber is introduced into the simulation model, and the complicated boundary shape of ball bearing is developed. Meanwhile, the simulation model is divided by the hexahedron elements and the mesh density near the contact region is increased, which promotes the convergence and accuracy of solution. Then, the lubrication performance experiment of ball bearing is conducted, which demonstrate that this model could capture the lubrication characteristics of ball bearing. Moreover, the evolution of hydrodynamic behavior, including the oil-air distribution, temperature and flow characteristics during different lubrication states, is displayed. The effects of structure characteristics and working condition are quantified. The results represent that the suitable clearance size could improve the internal flow patterns and hydrodynamic performance of ... Read More

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The rapeseed oil is a promising eco-friendly lubricant for applications involving environment protection. But any vegetal oil has shortcuts especially related to low viscosity and thermal stability. Research in additivation with nanoparticles is of interest for improving load capability of the contact and for reducing wear. Other tribological characteristics, as friction coefficient, could oscillate around values offered by the neat vegetal oil, with more or less influence of the system behavior. The four-ball tester offer a reliable ranking of the tribological characteristics when comparing two or more lubricants. Usually, researchers used test parameters recommended in ISO 20623:2017 Petroleum and related products. Determination of the extreme-pressure and anti-wear properties of lubricants. Four-ball method (European conditions) and ASTM D2596:2020 Standard Test Method for Measurement of Extreme-Pressure Properties of Lubricating Grease (Four-Ball Method), implying 1500 rpm for 1 hour for normal regime. This study proposes to evaluate the tribological characteristics (friction coe... Read More

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Based on the analysis of the current state of test methods for wear of friction pairs and the need for methods with certain operating conditions, the problem of developing a theory of test methods for wear of friction pairs according to the ball-cylinder scheme was solved, which makes it possible to determine the parameters of wear models and the general characteristics of the wear resistance of materials. It is shown that the type of wear within the range of properties of the friction pair parameters ensures compliance with the basic conditions in contact: materials, lubrication, pressure, speed, temperature, type of movement, and other less significant factors. It has been established that one of the fundamental issues in the development and conduct of wear tests is to take into account the influence of the stationarity of the wear mode at a point. Test methods in steady and unsteady modes (transient mode) are different. The test method should be based on the solution of the contact problem for a friction pair sample-counter-sample. Based on the solution of wear-contact problem for... Read More

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This work focused on the experimental study of grease lubrication mechanisms around contacts in radial ball bearing 6314. The main objective of this work was to show the influence of conformities and their impact on grease lubrication in ball bearings. For the experiments, a tribometer of ball-on-ring configuration was used and fluorescence microscopy was chosen as the observation method. The results showed that, under starvation conditions, a conformity of 0.52 at velocities around 2 m/s produces a 50% thicker lubricating film than a conformity of 0.58. The available amount of lubricant around the contact area for conformity 0.52 was approximately three times less than that for conformity 0.58, and the same ratio was observed for the amount of lubricant on the rolling track. Experiments show that a realistic tribometer geometry allows a more accurate experimental study of the lubrication mechanisms of greases in ball bearings.

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Abstract The tribological and vibration behaviors of a lubricated system are often studied separately. However, in recent years, the combination of tribology and mechanical vibration significantly contributes in analyzing and solving many practical problems. The main objective of this study is to establish empirical equations that describe friction-vibration interactions under dynamic (sliding) lubricated contacts. The effects of operating conditions on the tribological and vibration behaviors of lubricating oils having different viscosities were experimentally investigated using a four-ball wear test machine. The results indicated that the vibration velocity tends to increase with the sliding velocity. With a lower combination of ratio of the vibration velocity to the sliding velocity and the specific film thickness, lower friction coefficients were observed in the boundary and mixed lubrication regimes. The mean wear scar diameters exhibited positive correlations with the amplitudes of vibration accelerations. The empirical equations provide basic information for the prediction of... Read More

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Abstract Owing to the measurement difficulty and the required time needed to analyze wear processes of ball screws, very few studies have been reported. Here, on the basis of a test bench and a Taylor Hobson surface profilometer, the measuring procedure for the raceway surface profiles of ball screws was proposed first. Then the raceway surface profiles of a typical ball screw were measured after 1.42 million running revolutions. Finally, a combinational method including the statistical parameters, recurrence analysis, and fractal dimensional was used to characterize the lubricated wear process. Results show that the increase of the surface roughness (Ra) and maximum peak-to-valley height (Rz) can be up to 396% and 395%, the recurrence rate can decrease more than 59%, and the ratio between the minimum and maximum values of the fractal dimension can be 77% after 1.42 million running revolutions. Further analysis showed that the three methods all reflected the raceway wear dependence on the number of revolutions, and the linear correlation of the fractal dimension method with the numbe... Read More

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The purpose of this research is to analyze the viscosity/viscosity of lubricating oil using the relative motion method of falling balls at various temperatures. This research is using experimental method. Where the test is carried out using temperature variations of 320C, 500C, 600C and 800C, steel balls with varying diameters, including 9.50 mm, 8.00 mm, 6.00 mm and 4.80 mm as well as variations in the viscosity of lubricating oil, including SAE. 10, SAE 40, SAE 90 and SAE 140. Data analysis used the method of calculating the fluid resistance equation of Stokes' law and the equation of motion from Newton's second law. The Stokes law equation by taking the example of a lubricant with a viscosity of SAE 10 is obtained for a steel ball diameter of 9.50 mm to obtain a fluid resistance of 7.159.200 m/s2, a steel ball with a diameter of 8.00 mm to obtain a fluid resistance of 6.028.800 m/s2, for a steel ball with a diameter of 6.00 mm obtained a fluid resistance of 4.521.600 m/s2, for a steel ball with a diameter of 4.80 mm, a fluid resistance of 3.617.280.000 m/s2 was obtained. It can be... Read More

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The paper presents some typical results regarding the evolution of friction torque during the four balls scuffing tests. The tests were conducted in 10 seconds running periods having 100 N loading steps, according to ISO 20623:2017. For testing, 12.7 mm bearing balls manufactured by SKF were used and as lubricant, U90Ca3 grease was used. A special device was conceived and built to evaluate the friction torque between balls using a force transducer mounted on the testing machine and a data acquisition module. A correlation between the loading, wear scar dimensions and friction torque was obtained. The results can be used to determine the precursory moment of scuffing initiation in four ball test using different lubricants. Some remarks concerning the working parameters inter-correlation during tests were also made.

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The lubricating film, generated between two surfaces in relative motion, may have theoretical thicknesses between 10 -10 m and 10 -5 m. This paper presents a model for calculating the minimum film thickness depending on load, sliding speed and temperature for rapeseed oil working as lubricant in a point contact and a method of designing maps of lubrication regimes for a punctual contact. The results are useful in introducing this vegetal oil in actual applications. data for viscosity-temperature dependence of the rapeseed oil are taken from literature and for the same regime parameters tests are reported on the four-ball tester. The results pointed out the sensitivity of rapeseed oil to regime parameters (load and sliding speed), but also to temperature. Calculations are done for temperatures measured in actual functioning of the four-ball tester lubricated with rapeseed oil.

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In this paper the authors theoretically evaluated the film thickness in a miniature angular contact ball bearing in grease and oil lubricated conditions and correlated with the variation of the electrical resistance experimentally determined by using tribometer CETR UMT-2. For grease the authors determined the film thickness considering base oil viscosity. The rotational speed of the inner race varied between 1 and 500 rpm and the axial load applied on a 7000C angular contact ball bearing was 8.1 N. The IVR and EHD lubrication regimes were analytically evaluated depending on the rotational speed and lubricants for both inner and outer race. Based of the dependence between film thickness and electrical resistance obtained for oil was evaluated the real film thickness obtained by using the grease. In case of oil lubricated condition, the experimental results showed an increase of electrical resistance with the rotational speed caused by increasing of the film thickness according to the theoretical model. For grease lubricated condition, a V-shaped pattern was obtained. High values of... Read More

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Wear particles are produced in all oil-lubricated machines when mechanical parts come in contact. These particles are generated in differing sizes, altering quantities, with specific composition, and morphology. The particles when examined by

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Parts of rolling bearings lubricated with low-viscosity fluids are subject to intense wear of the working surfaces. The bearing life cycle under these conditions depends on the wear rate of the friction surfaces. Therefore, it is important to establish the relationship between the wear rate, the change in the clearances and the duration of work. This paper presents the results of wear tests for rolling ball bearings. After the tests the radial and axial clearances were measured, their changes and the duration of operation were analyzed. Having determined the path of friction, the wear rates of the bearings were calculated based on the values of changes in the radial and axial clearances. The wear rate of the bearing on the axial and radial clearances was plotted against the reduced (equivalent) load. The obtained dependences were approximated with a confidence of at least 98%. The obtained analytical expressions allow us to perform express calculations for changes in the bearing clearances. This will make it possible to forecast the bearing service time, taking into account the wear ... Read More

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Purpose Formulation of mineral-based specialty lubricants without anti-wear (AW) and extreme-pressure (EP) additives is a challenging task. This study aims to propose an environment friendly alternative to mineral-based lubricants with superior wear preventive characteristics. Design/methodology/approach In this study, analysis of wear under trimethylolpropane trioleate (TMPTO)-based lube using operating parameters of four-ball tester was done. The effects of type of lube oil, temperature, load and speed on specific wear rate were investigated using Taguchi L27 orthogonal array. Based on the Taguchi experimental results and single-to-noise ratios, ranking of the four ball parameters was done. The surface analysis of worn steel balls was carried out using optical microscopic images of wear scar and energy dispersive spectrometry (EDS). Findings Results depict that the blend of sulfurized additives with TMPTO base oil showed a synergistic effect in terms of reduction in specific wear rate by the formation of protective film layer on the surface. The possible physical or chemical intera... Read More

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A high-throughput tribometer for wear testing that automates counterface exchange between tests, enabling unattended operation for multiple tests. The system features a carousel with exchange tools, a selector motor, and an exchange drive motor to rapidly and automatically replace the counterface between tests, reducing operator interaction and increasing testing efficiency.

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