What are the common failure modes of four-point contact ball slewing rings?

What is four-point contact ball slewing ring

The four-point contact ball slewing ring is a kind of mechanical transmission parts with exquisite structure and excellent performance, and its core structure includes the inner ring, the outer ring, the steel ball and the cage, and the arc raceway of the inner and outer rings forms a unique four-point contact mode with the steel ball. This innovative design gives it strong mechanical properties, efficient handling of axial, radial and overturning forces at the same time, excellent load-bearing capacity and good stiffness characteristics thanks to a uniform distribution of contact stresses. When working, it relies on the rolling of the steel ball in the raceway to realize the flexible rotation between the inner and outer rings to ensure the stability and accuracy of the equipment operation. In practical applications, it can be seen from heavy-duty cranes and excavators, to wind turbines in the field of clean energy, to rotary workbenches on automated production lines, and is a key component of many equipment that requires rotary movement and has high requirements for load bearing and accuracy.

Features of four-point contact ball slewing rings

High bearing capacity: The unique four-point contact structure makes the steel ball have four contact points with the inner and outer ring raceways, which can withstand axial force, radial force and overturning moment at the same time, and can adapt to complex stress conditions with high bearing capacity.

Good rotation accuracy: the steel ball rolls in the raceway, the movement is stable, and the uniformity of the four-point contact helps to ensure the accuracy of the rotary movement, which can meet the application scenarios with high requirements for rotary positioning accuracy.

Compact structure: Compared with some other types of slewing rings, under the same bearing capacity, the structure of four-point contact ball slewing rings is relatively compact, and the space occupied is small, which is conducive to the miniaturization design of equipment.

Easy installation: its structure is relatively simple, the installation process is relatively convenient, and there are usually mounting holes on the inner and outer rings, which are convenient for connection and fixation with other parts of the equipment, which can effectively improve the installation efficiency.

Low maintenance cost: rolling friction is adopted, the friction coefficient is small, the wear is relatively small, and it is generally equipped with a good sealing and lubrication system, which can effectively reduce the intrusion of external impurities and the wear of components, thereby reducing maintenance costs and prolonging service life.

Strong adaptability: According to different work requirements, by changing the material, surface treatment process and structural parameters, etc., to meet the needs of various harsh working environments and special working conditions, such as high temperature, low temperature, high humidity, corrosive environment, etc.

What are the common failure modes of four-point contact ball slewing rings?

The common failure modes of four-point contact ball slewing rings are as follows:

Wear and tear

Raceway wear: After long-term use, the raceway surface will be worn due to repeated contact and friction with the steel ball. Abrasion will lead to an increase in the surface roughness of the raceway, a decrease in dimensional accuracy, a decrease in the rotation accuracy of the slewing ring, and a possible shaking or stagnation during operation.

Steel ball wear: The steel ball rolls in the raceway and is subject to large contact stress, which is prone to wear. After the steel ball is worn, its roundness and diameter size will change, which will affect the bearing capacity and smooth operation of the slewing ring, and may also lead to an increase in noise.

Fatigue flaking

Raceway fatigue spalling: Under the action of alternating load, fatigue cracks will occur on the surface of the raceway, and with the expansion of cracks, the surface material will gradually peel off, forming pitting or pits. This will destroy the surface integrity of the raceway, worsen the contact state between the steel ball and the raceway, and lead to increased vibration and noise of the slewing ring, which in severe cases will affect the normal operation of the equipment.

Steel ball fatigue spalling: Steel balls can also peel due to fatigue. Spalling on the surface of the steel ball will change its contact point with the raceway and the distribution of contact stress, further exacerbating wear and fatigue, and reducing the service life of the slewing ring.

Poor lubrication

Insufficient lubricant: If the lubricant is not replenished in time or the lubrication system fails, it will lead to a lack of sufficient lubrication between the raceway and the steel ball inside the slewing ring, thereby increasing the frictional resistance, aggravating the wear, generating a lot of heat, and affecting the performance and life of the slewing ring.

Lubricant deterioration: Long-term use of lubricants will deteriorate due to oxidation, pollution and other reasons, and lose good lubricating properties. Deteriorated lubricants are unable to form an effective oil film on the surface of the raceways and steel balls, resulting in direct metal contact and accelerated wear and fatigue.

Seal failure

Seal aging: After long-term use, the seal will be aging, cracking and other phenomena, and lose its sealing performance. Dust, moisture and impurities from the outside world will enter the inside of the slewing ring, contaminate the lubricant, aggravate the wear, and the internal lubricant will also leak, affecting the lubrication effect.

Damaged seals: Seals can be damaged due to improper installation, external impact, or long-term friction with slewing parts. After the seal is damaged, the sealing function is lost, and the working environment inside the slewing ring deteriorates, which is easy to cause various failures.

Improper installation

Insufficient installation accuracy: if the installation surface of the slewing ring is uneven, the horizontality or verticality does not meet the requirements during installation, the slewing ring will bear uneven load during operation, resulting in aggravated local wear and raceway deformation, affecting the service life and slewing accuracy of the slewing ring.

Loose bolts: If the bolts connecting the slewing ring are not tightened or loosened due to vibration and other reasons during operation, the connection of the slewing ring will not be firm, and displacement and impact will be generated during operation, damaging the raceway and steel balls, and may even lead to the slewing ring falling off and causing safety accidents.

Four-point contact ball slewing ring supplier

As a well-known supplier of slewing bearings with 30 years’ experience, LTZC bearings is committed to providing slewing bearings with high quality and low price. The specific price needs to be comprehensively evaluated according to the size, load, material and accuracy requirements of the bearings. Please contact us if necessary.