Sealed bearing are divided into, contact and non-contact.
2RS is the bearing with skeleton type rubber seal (contact) on both sides. RZ is the bearing with skeleton type rubber seal (non-contact) on both sides.
The basic dimensions of the two types of bearings are the same. Whether they can be used universally depends on your application. The sealing effect of RS is better than RZ, but the friction resistance is slightly higher. If you require a good seal, such as no oil leakage, it is best to use RS.
Non-contact sealing device: Non-contact sealing device does not contact with the shaft and does not produce friction, there are types of oil grooves, oil dumping rings and labyrinth seals. These devices are used to seal with tiny gaps or centrifugal force, especially suitable for high-speed rotation and high temperature occasions.
Contact sealing device: Contact sealing device is the use of synthetic rubber, synthetic resin, felt and other materials to play a sealing role in the frictional contact between the end and the rotating body, synthetic rubber oil seals are most commonly used.
The following is a contact seal ：
The following are non-contact seals ：
The purpose of sealed bearing is to prevent the leakage of lubricant from the bearing part and to prevent harmful objects such as external dust, dirt, metal particles, moisture, acidic gas and other debris from entering the inside of the bearing so that the bearing can operate safely and continue under the required conditions.
The general term for the devices made for this purpose is sealed bearing. If the bearing seal is not secure and external debris intrudes, the working condition of the bearing will be greatly deteriorated and the service life of the bearing will be greatly shortened.
The seal is responsible for maintaining the operational performance and durability of the bearing. Grease-lubricated seals are easier to obtain, while oil-lubricated seals are more difficult to obtain. Seals can also be used in the form of sealed bearings.
The most straightforward explanation is that when we look up the bearing model number, we often see the letters behind the bearing model number: ZZ series bearings, 2RZ, 2RS, 2RSW, 2RSH. These letters represent different types of sealed bearing, and another type of seal is the bearing compound seal. According to the knowledge of sealed bearing, share the use environment of these sealed bearings, the meaning of each seal model, the characteristics of various types of seals and the advantages and disadvantages of various types of seals
A, ZZ – dust cover seal
Z: bearing with iron dust cover on one side.
ZZ: bearing with iron dust cover on both sides. (The dust cover is stamped with abrasive tools and pressed into the bearing with abrasive tools. The bearings sealed with dust caps are non-contact seals, mainly used for dustproofing and sealing of the bearings)
ZZ series bearings use environment: motor, etc. Can be used in high and low temperature conditions.
Advantages: low cost, small starting torque,. Disadvantages: large sealing gap (generally above 0.4mm), low dustproofness.
II. RZ-Non-contact rubber cover seals
Use environment: motor, etc.
Advantages.
1、The two sealing lips are not in contact with the bearing, low starting torque and low heat generation.
2、Low manufacturing precision requirement for seal ring and sealing labyrinth groove, relatively low cost.
3, labyrinth seal structure, good dustproof effect.
Disadvantages: sealing gap MAX0.2mm, not resistant to dust, mud and water vapor occasions
Three, RS-light contact rubber cover seals
RS: bearing steel liner on both sides with synthetic rubber contact seal, Sweden SKF company said
2RS: sealed with both sides of the bearing, Germany FAG bearing company representative
Use environment: motor, pump, car tensioner, etc.
Advantages.
1、A slight increase in starting torque and heat generation due to axial contact between the main lip and the labyrinth seal groove.
2、Because the main lip is in axial contact with the seal, the two secondary lips are sealed with radial gap, which has better dustproof effect.
Disadvantages.
1. higher requirements for the shape of sealing groove and sealing ring.
2. Does not have the waterproof effect.
IV. RSW-recontact rubber cover seals
Use environment: automotive tensioner, automotive condensing fan, etc.
Advantages.
1. three-lip seal with optimized design of main lip angle and axial interference to prevent excessive starting torque.
2、The elongated first lip forms a small gap seal to prevent lubricant leakage and water vapor entry.
3、The joint cooperation of the second sub-lip realizes the comprehensive effect of radial sealing and axial sealing, and at the same time extends the seal’s resistance to mud and water and wear resistance.
Disadvantages.
1、Higher requirements for the shape of the sealing groove and seal ring.
2、Long-term immersion operation weakness.
3, large starting torque, affecting the motor power.
V. RSH-high contact rubber cover seal-(power hub structure)
Use environment: automotive water pumps, industrial water pumps, electric motorcycles, agricultural machinery, etc.
Advantages.
1、Used for special water vapor erosion needs.
2、Inner sealing lip improves the grease retention ability.
3、Imported reinforced rubber material, which can better prevent water vapor from entering the bearing.
4、Optimized structure of sealing lip in order to reduce torque and improve sealing performance.
5、Since the sealing contact surface is processed with high precision, the friction loss of the sealing material is reduced and the sealing life is extended.
6、The special seal lip design can automatically compensate for the wear of the seal.
Disadvantages: large friction torque.
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