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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