Bearing failure modes vary, but extensive practical application and life testing confirm that contact surface fatigue is a common failure mode.
According to the ISO 25243-2004 standard, fatigue is listed as the first of the six common bearing failure modes. While fracture ranks sixth, fatigue also plays a role in its formation, hence the name fatigue fracture. Fatigue failure is primarily categorized as subsurface-originated and surface-originated.
Subsurface-originated fatigue
Subsurface-originated fatigue occurs when the maximum contact stress generated by rolling contact occurs at a certain depth below the surface. Under the repeated action of alternating stress, fatigue sources (microcracks) form at this location.
Under cyclic stress, these crack sources gradually propagate to the surface, forming open, flaky cracks. When cracks are torn into flaky particles and peel off from the surface, pitting and cratering occur. Weak points or defects in the bearing steel, such as non-metallic inclusions, air gaps, and coarse carbide intergranular interfaces, accelerate the formation of fatigue sources and the propagation of fatigue cracks, thereby reducing fatigue life.
Surface-Origin Fatigue
Surface-origin fatigue is caused by damage to the contact surface. This damage may occur during the manufacturing process, such as scratches and dents, or during use, such as from hard particles in the lubricant or micro-abrasions caused by the relative motion of bearing parts.
The damaged area may be due to poor lubrication, such as lubricant starvation or lubricant failure. This can exacerbate the relative sliding between the rolling elements and raceways, leading to microcracks at the base of the asperities in the damaged surface. Crack propagation can cause the asperities to break off or form flaking areas. These flaking areas are shallow and can sometimes be confused with dark gray pitting.
Fatigue Fracture
Fatigue fracture is also caused by the combined effects of assembly stresses generated by an overly tight fit and cyclic alternating stresses. When the balance between assembly stresses, alternating stresses, and the yield strength is disrupted, fractures occur along the ring axis, forming through-hole cracks. In practical applications, most bearing failures are caused by contact surface fatigue. Of the three fatigue failure types, subsurface-origin fatigue is the most common. Therefore, the bearing life calculation methods recommended by ASO281 and ISO281/amd.2 are both based on subsurface origin fatigue.
About LJHB:
LuoYang JinShuo Precision Bearing Co., Ltd. is mainly committed to the R&D and sales of high-precision bearings and other special products, and provides bearings and transmission parts with high performance for customers' equipment. With quick response, from pre-sales technical communication to on-time production delivery, as well as perfect after-sales service, we win the recognition and trust of customers.
Our main products include cylindrical roller bearings, tapered roller bearings, slew bearings, gear drives, spindle bearings, crossed roller bearings, turret bearings, thin-wall bearings, tandem roller bearings, spherical roller bearings, etc. The bearing dimensions rang from 100mm to 6000mm, the accuracy reaches P5, P4 and P2 levels. The bearing are widely used in mining and metallurgy, industrial equipment, industrial gearboxes, petroleum equipment, cranes, medical equipment, robotic equipment, etc. Among them, cylindrical roller bearings with better performance and high-precision deep groove ball bearings have been explored for high-speed tubular strander rotating cable equipment, which have completely replaced imports, saving customers costs and time, and improving work efficiency. It has been recognized and widely praised by customers.
Contact LJHB:
Address: Yiyang Bearing Industry Zone, Luoyang City, China 47100
Tel/Wechat: +86-18037970383
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E-mail: lyjh@lyjhbearing.com
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