What are the differences between sealed and unsealed versions of deep groove ball bearings

Deep groove ball bearings are widely used in industries such as industry, automobiles, home appliances, and wind power generation. Their unique design enables them to withstand a variety of loads and high speeds. According to different working environments and usage requirements, deep groove ball bearings have two main versions: sealed and unsealed. The main differences between the two are in terms of sealing, lubrication method, applicable environment, and maintenance requirements. Understanding these differences will help you make more accurate decisions when choosing bearings.

Definition of sealed and unsealed deep groove ball bearings
Sealed deep groove ball bearings: Sealed deep groove ball bearings use special sealing devices (such as rubber seals or metal seals) to prevent external contaminants from entering the bearing and to maintain the lubricating grease or lubricating oil inside the bearing. Seals are usually divided into internal seals and external seals, which can effectively protect the bearing from water, dust, oil and other contaminants.
Unsealed deep groove ball bearings: Unsealed deep groove ball bearings do not have a closed structure, and the inner and outer rings of the bearing are open, which is easily invaded by external contaminants. Therefore, the lubrication method of unsealed bearings relies more on regular filling of lubricating oil or grease, and its applicable environment is usually relatively clean, or requires external protection devices.

Main differences between sealed and unsealed versions
Protection function
One of the biggest advantages of sealed deep groove ball bearings is its protection function. Due to the presence of the seal, the lubricant or fat inside the bearing can be better maintained, and external contaminants (such as dust, moisture, corrosive chemicals, etc.) are not easy to enter the bearing. This makes the service life of sealed bearings usually longer in harsh environments, especially in humid or dusty working environments, which can significantly reduce bearing wear and failure caused by contamination.
Unsealed deep groove ball bearings lack this protection and are easily contaminated by external contaminants. When dust, impurities, etc. enter the bearing, they will increase wear and affect the performance and life of the bearing. Non-sealed bearings are more suitable for applications that require regular oiling and cleaning.
Lubrication method
The lubrication system of sealed deep groove ball bearings usually adopts closed lubrication, that is, grease or oil is filled inside, and the lubrication effect of the bearing is maintained by the seal. This design enables the bearing to reduce the loss of lubricant during long-term operation and has a long maintenance cycle. In some special applications, the lubricant of sealed bearings is specially designed to withstand high temperatures or high loads and improve work efficiency.
In contrast, the lubrication of non-sealed deep groove ball bearings relies on regular external refueling. Usually, the lubricating oil or grease of non-sealed bearings needs to be checked and replenished regularly to keep the bearings running normally. The loss of lubricating oil may lead to increased friction, which in turn increases the bearing temperature and reduces the service life of the bearing.
Adaptability to working environment
Sealed deep groove ball bearings are suitable for harsh working environments, especially places with a lot of dust, moisture or corrosive substances. Due to the effective protection of the sealing structure, the bearings can work normally in such environments, such as in mechanical equipment, pump equipment, fans and other industries.
Non-sealed deep groove ball bearings are suitable for cleaner working environments and are commonly found in high-precision industrial equipment such as motors and precision instruments. Due to the lack of sealing devices, such bearings are usually not directly exposed to dust, oil or moisture-rich environments, otherwise they are prone to corrosion and wear.
Maintenance and replacement cycle
Sealed deep groove ball bearings reduce the entry of external pollutants due to the protection of the sealing effect, and the grease or oil inside the bearing can maintain its effectiveness for a longer time, thereby extending the maintenance and replacement cycle. Compared with unsealed bearings, sealed bearings generally require less maintenance, reducing maintenance costs and downtime for enterprises.
Unsealed deep groove ball bearings require more frequent inspection and lubrication. Because there is no seal protection, these bearings need to be greased and checked more frequently during use. Once insufficient lubrication or external contaminants enter, the bearing is prone to failure, so the maintenance workload of unsealed bearings is relatively large.
Cost difference
Sealed deep groove ball bearings are generally more expensive. This is because the sealed design requires additional seals and materials, and the manufacturing process is more demanding. Unsealed deep groove ball bearings, on the other hand, have a relatively low production cost due to their simpler structure. Therefore, in cost-sensitive applications, unsealed bearings may be a more attractive choice.

Application areas of sealed and unsealed versions
Applications of sealed deep groove ball bearings generally include:
Automotive industry: such as wheel hub bearings, wheel drive systems, etc. In these parts, sealed bearings can effectively prevent the influence of external moisture and dust on the bearings.
Household appliances: such as washing machines, power tools, etc., sealed bearings can extend the service life of equipment and reduce maintenance work.
Food processing and pharmaceutical industries: These environments have extremely high requirements for cleanliness, and sealed bearings can effectively prevent external contaminants from entering.

Applications of unsealed deep groove ball bearings usually include:
High-precision mechanical equipment: such as CNC machine tools, precision instruments, etc., unsealed bearings can maintain high precision and low cost.
High-temperature, high-speed environments: such as wind turbines, aviation equipment, etc., unsealed bearings can provide better high-temperature performance and are easier to perform precise lubrication control.