Service Life of Lubricating Grease in Ball Bearings (Part 1) Behavior of Grease and Its Base Oil in a Ball Bearing

Komoriya, Tomonobu; Ichimura, Ryosuke; Kochi, Tsuyoshi; Yoshihara, Michitaka; Sakai, Masataka; Dong, Daming; Kimura, Yuuji

doi:10.2474/trol.16.236

Cited by 9 publications

(5 citation statements)

References 8 publications

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“…However, no increase in chromium was found indicating that the iron particles must originate from the cage. This confirms the conclusions from the tests of Komoriya et al [45] where the cage started wearing earlier then the raceways in their grease lubricated bearings. The iron particles act as catalysts for the oxidation reaction [47], creating again more iron containing particles, accelerating oxidation again, etc..…”

Section: Iron Contentsupporting

confidence: 90%

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Impact of oxidation on grease life in rolling bearings

Lugt

Holgerson

Reinholdsson

2023

Tribology International

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Section: Iron Contentsupporting

confidence: 90%

“…For the tests in a nitrogen environment this does not change. A similar result was shown by the best performing grease of the two greases that were tested by Komoriya et al [45].…”

Section: Oil Contentsupporting

confidence: 79%

Impact of oxidation on grease life in rolling bearings

Lugt

Holgerson

Reinholdsson

2023

Tribology International

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“…In addition, any of the surfaces of the cage pockets were considered to be adhesive wear. Since adhesive wear was observed in the cage pockets after the test and the contact area between the rollers and the cage is prone to poor lubrication with grease lubrication [28], the contact area between the rollers and the cage was likely in direct contact during the test. The wear shapes were measured for all 16 pockets of the cage using a contact-type profilometer, from which the volume of cage wear was calculated.…”

Section: Determining Wear Modesmentioning

confidence: 99%

Study on Cage Wear of Railway Traction Motor Bearings Based on Analysis of Rolling Element Motion

et al. 2023

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Cylindrical roller bearings used in traction motors for railway vehicles are used at high rotational speeds and under light loads. Under these operating conditions, the life due to cage wear is much shorter than the life due to raceway fatigue. Therefore, bearing life can be extended by reducing cage wear. The authors thought that to reduce cage wear, it is necessary to establish a dynamic analysis method for the contact between the roller and the cage, and to identify the wear mode of the cage. If cage wear follows Archard’s equation, then cage wear is proportional to the impulse caused by the contact between the rollers and the cage. Therefore, in this paper, a simple model consisting only of a roller and a cage was constructed, and the impulse was obtained via dynamic analysis. The impulses calculated by the dynamic analysis were in good agreement with those measured. In addition, the experiments showed that cage wear is proportional to the impulse and revealed the wear mode of the cage. These allow the method proposed in this paper to be used to predict cage wear and to determine bearing specifications to reduce cage wear.

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“…The grease bleeding will supply oil to the raceway contacts: either it bleeds oil due to severe shear on the raceway or small fresh quantities of grease may be sheared off from the volume stored on the shoulder. Tomonobu Komoriya et al [3] carried out an experimental investigation on angular contact ball bearing lubricated with urea greases and observed lumps of grease created on the front face of the outer ring, on the shoulder of outer ring, on the inner surface of the cage, on the shoulder of the inner ring. These lumps served as grease reservoir and oil bled from here migrated to lubricate the raceways.…”

Section: Introductionmentioning

confidence: 99%

A novel numerical analysis method for predicting non-Newtonian lubricant (grease) distribution in ball bearings

Pandya,

Tesini,

Bogliacino

et al. 2024

EMAS

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Grease is a visco-elastic fluid and the most common lubricant for rolling bearings. During the churning phase (initial phase) of bearing operation, most of the grease is collected at various locations in the bearing, e.g. by the seal, at the bottom cage bar, in the cage pockets, which are then called grease reservoirs. These are formed based on bearing operating conditions, grease type, bearing geometry, bearing type. The grease reservoirs supply lubricant to the bearing contacts via bleeding: during operation the oil bleeds out of the reservoirs and lubricates the contacts. Since the distribution of grease is crucial to the bearing lubrication, the design of bearing components e.g., the cage, shall aim at an optimal grease reservoir creation during the churning phase. It is difficult to observe the effect of component design on the grease distribution through real life experiments, so CFD simulations with MPS (Moving Particle Semi-implicit) method are performed here. Flow Simulations with MPS method can help determine the factors influencing the grease distribution inside the bearing after churning, with the final aim of enhancing lubrication. For the current simulations, a CAE software based on MPS, namely Particleworks, was used. Grease consists of a base oil, a thickener, and additives. Since it is a non-Newtonian fluid, it has a nonlinear relation shear stress vs shear rate. It is a visco-elastic material, so it does not flow in the absence of a threshold force. For current simulations, the grease rheology has been modelled using the Herschel-Bulkley model. The model was fitted on in-house rheometer test data and was reduced to a single cage-ball segment. All critical kinematic properties were preserved, that is the speeds of both the inner ring and ball surfaces and the oscillation of the ball position within the pocket as it travels through the loaded and unloaded zones of the bearing. The location and the duration of grease injections resulted in different grease distributions in the model. For demonstration purposes, this document only focuses on the results obtained injecting a grease layer on the inner ring surface in front of the contact. This realistically predicted grease reservoirs to be located at the cage bottom, on the top of cage and in the cage pockets. Sensitivity study on particle size, time step, surface tension and the parametric variation of the bearing speed were also performed. This is an important milestone, as we are able for the first time to virtually simulate the onset of grease reservoirs at locations corresponding to evidence from real bearing operations. The distribution of grease observed at the cage pockets is very important for oil film replenishment. This outcome gives us confidence that the MPS method can be used to support the design of bearing components contributing to enhanced lubrication.

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Service Life of Lubricating Grease in Ball Bearings (Part 1) Behavior of Grease and Its Base Oil in a Ball Bearing

Cited by 9 publications

References 8 publications

Impact of oxidation on grease life in rolling bearings

Impact of oxidation on grease life in rolling bearings

Study on Cage Wear of Railway Traction Motor Bearings Based on Analysis of Rolling Element Motion

A novel numerical analysis method for predicting non-Newtonian lubricant (grease) distribution in ball bearings

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