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What are the failure modes of four – point contact slewing bearings?

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Four – point contact slewing bearings have various failure modes. Each failure mode seriously affects its performance and the operation of the equipment.

What is Four – Point Contact Slewing Bearing

A four – point contact slewing bearing is a type of bearing structure. It consists of components such as an inner ring, an outer ring, rolling elements, and a cage. Its uniqueness lies in that the rolling elements have four – point contact with the raceways of the inner and outer rings, enabling it to simultaneously withstand axial forces, radial forces, and tilting moments. This design gives the slewing bearing a high load – carrying capacity and rotational accuracy within a limited space. It is commonly used in construction machinery and large – scale equipment such as cranes, excavators, and wind turbines. It can achieve smooth rotational motion between components, adapt to complex working conditions, and improve the reliability and stability of the equipment.

Failure Modes of Four – Point Contact Slewing Bearings

Wear

– Raceway Wear: When a four – point contact slewing bearing is in operation, the steel balls continuously roll within the raceways. There is relative motion and contact pressure between them. After long – term operation, the surface of the raceway will gradually wear due to friction. The wear increases the surface roughness of the raceway, making the originally smooth raceway rough. This leads to an increase in the friction force between the steel balls and the raceway, and an increase in energy consumption during operation. At the same time, the dimensional accuracy of the raceway decreases, affecting the rotational accuracy of the slewing bearing and reducing the operating stability of the equipment. For example, in some frequently rotating robotic arms, raceway wear may cause a decrease in the positioning accuracy of the robotic arm, affecting its work quality.

– Cage Wear: The cage is used to separate the steel balls and guide them to roll correctly within the raceways. During the operation of the slewing bearing, there is a certain amount of relative motion and friction between the cage, the steel balls, and the inner and outer rings. If the material of the cage has insufficient wear resistance or the lubrication is poor, wear is likely to occur. After the cage is worn, its guiding and positioning function for the steel balls is weakened. The steel balls may become skewed and collide with each other, further aggravating the wear of the steel balls and the raceway. In severe cases, the steel balls may even come out of the raceway, causing the slewing bearing to fail.

Fatigue Spalling

– Raceway Fatigue Spalling: When a four – point contact slewing bearing is working, the surface of the raceway bears periodic contact stress. Over time, under the action of this alternating stress, the metal material on the surface of the raceway gradually fatigues. Initially, tiny cracks appear at the microscopic level on the surface of the raceway. These cracks will continue to expand as the number of operating cycles increases. When the cracks expand to a certain extent, the metal on the surface of the raceway will spall off, forming fatigue spalling pits. These spalling pits damage the surface integrity of the raceway, deteriorate the contact state between the steel balls and the raceway, cause vibration and noise during the operation of the slewing bearing, reduce the working performance of the equipment, and in severe cases, even affect the load – carrying capacity of the slewing bearing, resulting in the equipment being unable to operate normally.

– Steel Ball Fatigue Spalling: The steel balls also bear cyclic contact stress, and their surfaces are prone to fatigue spalling. Once spalling occurs on the surface of the steel ball, it will change the contact points and contact force distribution between the steel ball and the raceway, intensify the stress concentration in other parts, and accelerate the further damage of the steel ball and the raceway. Moreover, the spalled metal debris may enter the gap between the raceway and the steel ball, aggravating wear and scratching, and further shortening the service life of the slewing bearing.

Plastic Deformation

– Overload Plastic Deformation: When the load borne by a four – point contact slewing bearing exceeds the yield strength of its material, the metal on the surfaces of the raceway and the steel balls will undergo plastic deformation. This deformation usually manifests as pits or protrusions on the surface of the raceway, and the shape of the steel balls may also change. Plastic deformation destroys the original accuracy and geometric shape of the slewing bearing, increases the fit clearance between the steel balls and the raceway, and causes the slewing bearing to shake and become unstable during operation, seriously affecting the working accuracy and reliability of the equipment. For example, in some large – scale cranes, if the slewing bearing undergoes overload plastic deformation, it may cause the jib to shake significantly during rotation, endangering the safety of the hoisting operation.

– Impact Plastic Deformation: When the equipment starts, brakes, or is subjected to external impact loads, the four – point contact slewing bearing will bear a large instantaneous impact force. This impact force may cause local plastic deformation on the surfaces of the raceway and the steel balls. Although the action time of the impact load is short, if the impact force is large enough, it will still cause serious damage to the slewing bearing. Impact plastic deformation may form tiny pits or deformed areas on the surfaces of the raceway and the steel balls. These areas will become stress – concentration points during subsequent operation, accelerating the generation and expansion of fatigue cracks and reducing the service life of the slewing bearing.

Corrosion

– Chemical Corrosion: Four – point contact slewing bearings are usually exposed to various environments. When they come into contact with water vapor, oxygen, and other corrosive media in the air, a chemical reaction occurs on the metal surface, forming corrosion products. For example, slewing bearings made of steel are prone to oxidation reactions in a humid environment, producing rust. Corrosion gradually erodes the material on the metal surface, weakens the strength and wear resistance of the material, and reduces the performance of the slewing bearing. As the corrosion intensifies, the surface of the slewing bearing becomes rough and uneven, and may even develop pits, affecting the fit accuracy between the steel balls and the raceway, increasing the operating resistance of the slewing bearing, and consuming more energy.

– Electrochemical Corrosion: If there is an electrolyte solution in the environment where the slewing bearing is located and there is a potential difference between different metal components, a galvanic cell will be formed, triggering electrochemical corrosion. For example, when the inner and outer rings of the slewing bearing are made of different metal materials or there are unevenness in the surface treatment process, electrochemical corrosion is likely to occur under the action of the electrolyte solution. Electrochemical corrosion accelerates the local corrosion rate of metal components, forming corrosion pits and cracks, and seriously affecting the structural integrity and load – carrying capacity of the slewing bearing.

Fracture

– Raceway Fracture: Raceway fracture is a relatively serious failure mode. The reasons may include defects in the material itself, such as inclusions and pores inside. When subjected to loads, stress concentration is likely to occur at these defective locations, triggering cracks and their expansion. In addition, residual stress generated during the processing process, if not effectively eliminated, may also cause the raceway to crack during subsequent use. Moreover, overload or long – term fatigue can also cause cracks in the raceway, eventually leading to fracture. After the raceway fractures, the slewing bearing cannot normally bear the load, the equipment will stop running immediately, and it may even cause safety accidents.

– Steel Ball Fracture: If there are internal defects in the steel balls during the manufacturing process, such as uneven structure caused by improper forging technology or heat treatment defects, when they are subjected to large impact forces or cyclic stress during use, they may fracture. After the steel ball fractures, it will damage the load – bearing structure of the slewing bearing, change the load distribution borne by other steel balls, accelerate the damage of other components, and may also cause the equipment to vibrate violently and produce abnormal noise.

– Cage Fracture: The cage plays an important role in the slewing bearing. If there are improper installation situations, such as over – tightening or under – tightening during installation, the cage will bear additional stress during operation. In addition, when the slewing bearing is subjected to large external impact forces or interferes with other components, the cage is also easily damaged. After the cage fractures, the steel balls will lose their restraint and may collide with each other and scatter within the raceway, resulting in the complete failure of the slewing bearing.

Price of Four – Point Contact Slewing Bearings

Materials are a crucial factor. Using high – quality steel and special alloys can enhance strength and wear resistance. This increases the cost, and thus the price will be higher. For example, slewing drives made of materials containing special alloys are more expensive than those made of ordinary materials. Machining accuracy is also important. High – precision machining requires advanced equipment and technologies, which increases the cost, and as a result, the product price is naturally higher. The slewing drives used in precision equipment generally have high prices. The manufacturing process also affects prices. Advanced processes can optimize performance but also increase costs, thereby raising the selling price.

Supplier of Four – Point Contact Slewing Bearings

LDB bearing company has risen from obscurity to become well – known in the industry, relying on its dedication to quality and pursuit of innovation. The company is located in Luoyang, Henan Province, where the bearing industry is developed, enjoying the advantages of industrial resources. For example, its self – developed straight – tooth gear slewing drives have high precision and strong stability, greatly improving the operation accuracy and efficiency of industrial welding robots. With high – quality products and attentive services, it has won numerous praises and is bound to create more glories in the future!

What is the use of the four – point contact ball slewing bearing?

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Four-point contact ball slewing bearings are widely used and have unique performance mechanical components, playing a crucial role in many industrial fields.

What is Four-point Contact Ball Slewing Bearings

In terms of structural design, it is extremely compact. Compared with other slewing bearings, it occupies significantly less space. This characteristic creates favorable conditions for the miniaturization and lightweight design of equipment, conforming to the current industrial trend of pursuing high efficiency and intensiveness. In terms of load – bearing performance, four-point contact ball slewing bearings are outstanding. They can simultaneously withstand axial forces, radial forces, and overturning moments, and can calmly handle various complex working conditions, laying a solid foundation for the stable operation of equipment.

During operation, its slewing accuracy is extremely high. The ingenious structure of the four-point contact balls greatly ensures the smoothness of slewing, effectively reducing vibration and noise, and providing a quieter and more stable operating environment. Moreover, the friction coefficient of this slewing bearing is small. Replacing sliding friction with rolling friction not only reduces the power required for driving and improves transmission efficiency but also reduces component wear, thus greatly extending the service life and reducing equipment maintenance costs. In addition, it has a variety of installation forms, and the installation dimensions tend to be standardized. Whether it is for the initial installation or later replacement, it is very convenient, further enhancing its practicality and versatility.

Application of Four-point Contact Ball Slewing Bearings

In port container cranes, four-point contact ball slewing bearings play an irreplaceable and crucial role. The huge boom of the crane needs to slew frequently and smoothly to achieve the precise loading and unloading of containers. Relying on its high load – bearing capacity, the four-point contact ball slewing bearing can firmly support the huge weight of the boom and the axial forces, radial forces, and overturning moments generated when lifting containers. Its excellent slewing accuracy ensures that the boom can be accurately positioned every time it rotates, ensuring that the containers are placed in the designated position without error. The small friction coefficient enables the drive system to operate with low energy consumption and efficiently complete the loading and unloading tasks. The compact structural design realizes powerful functions within a limited space, laying the foundation for the overall performance improvement of the crane and facilitating the efficient operation of port logistics.

How to Extend the Service Life of Four-point Contact Ball Slewing Bearings

To extend the service life of four-point contact ball slewing bearings, it is necessary to start from multiple aspects. In the installation process, it is essential to strictly follow the standard procedures, use professional tools for accurate positioning, and ensure installation accuracy to prevent stress concentration or component misalignment caused by improper installation. During daily use, a scientific lubrication plan should be developed based on the equipment working conditions and operating hours. High – quality lubricants that are suitable for the equipment should be added on time and in sufficient quantities to reduce friction and wear between components. At the same time, closely monitor the operating status of the equipment. With the help of monitoring means such as sensors, real – time parameters such as the temperature, vibration, and noise of the slewing bearing can be obtained. Once any abnormality is detected, stop the machine immediately for troubleshooting and repair. In addition, pay attention to the storage environment of the equipment, and avoid being eroded by unfavorable factors such as humidity and corrosive gases. Through these comprehensive measures, the slewing bearing can be fully protected, effectively extending its service life.

Price of Four-point Contact Ball Slewing Bearings

The prices of four-point contact ball slewing bearings are affected by many factors. Raw materials are the foundation. Using high – quality steel, due to its better strength, toughness, and wear resistance, the cost is also higher. If inferior steel is selected, although the short – term price is low, it is prone to failures during long – term use. The complexity of the manufacturing process and the accuracy requirements are also very important. Precision processing equipment and strict quality control processes can ensure that the dimensional accuracy, surface roughness, and other indicators of the slewing bearing reach a high level, improving product performance and reliability. However, this will also increase the price. Products manufactured by simple processes may have a price advantage, but their quality and performance will be slightly inferior. The brand effect cannot be ignored. Well – known brands invest a lot in research and development, production, quality control, and after – sales service. Their products have passed long – term market tests, have a high degree of trust, and usually have higher prices. In addition, the market supply – demand relationship also affects the price. When the demand is strong and the supply is tight, the price rises; when the supply exceeds the demand, the price drops.

Supplier of Four-point Contact Ball Slewing Bearings

In the slewing bearing field, LDB Bearing is definitely a shining industry leader. Over the years, LDB Bearing has always adhered to the concept of quality first. Each four-point contact ball slewing bearing product is crafted through strict processes. From carefully selecting high – quality raw materials to ensuring high – precision production with advanced and precise processing equipment and mature technologies, every step is carried out with meticulous attention to detail. Its products have excellent load – bearing performance, can easily handle various complex working conditions, have extremely high slewing accuracy, operate smoothly, and greatly reduce the probability of equipment failures, escorting enterprise production. Moreover, LDB Bearing has a professional and efficient after – sales team that can solve problems for customers at any time and provide comprehensive technical support. Choosing LDB Bearing means choosing excellent quality and worry – free after – sales service. It is a wise choice to move towards efficient production and enhance competitiveness.