Bearing sealing seems to be an auxiliary design, but it directly determines the service life and operation and maintenance cycle of bearings. Especially in industrial environments such as dust, humidity, oil pollution and corrosion, choosing the wrong sealing form will easily cause bearings to fail early due to impurity intrusion and lubrication loss. The mainstream bearing seals on the market are divided into three categories: open type, single-side sealed type and double-side sealed type. This article explains their respective characteristics and applicable environments in detail, and clarifies the standardized selection logic.

Structural Characteristics: No seals or dust covers on the inner and outer rings of the bearing, completely exposed, rolling elements and cages are directly exposed to the outside, with simple structure and the lowest cost.Advantages and Disadvantages: The advantage is flexible installation, which can be filled with customized lubricating media by oneself and adapted to special working conditions; the disadvantage is no protective capacity at all, lubricating media are easy to lose, dust, water vapor and impurities are extremely easy to intrude into the interior, wear raceways and rolling elements, and the operation and maintenance frequency is extremely high.Applicable Scenarios: Only limited to clean, dry and closed internal environments, and the equipment is equipped with a complete sealing structure (such as machine tool spindle box, closed gearbox), or special equipment that needs to replace special lubricating media regularly. Not suitable for open-air and dusty scenarios.

Structural Characteristics: One side of the bearing is equipped with a seal cover/sealing ring (rubber seals and iron dust covers are common), and the other side is open, taking into account protection and the convenience of lubrication filling.Advantages and Disadvantages: The advantage is that one side can block impurities, the cost is slightly higher than that of open type and much lower than that of double-side sealed type, and grease can be supplemented from the open side in the later stage; the disadvantage is only single-side protection, there is still a risk of impurity intrusion on the other side, and the protective capacity is limited.Applicable Scenarios: Equipment with harsh environment on one side and relatively clean environment on the other side, such as motor shaft extension end, single side of fan, small transmission mechanism, or scenarios requiring regular maintenance and lubrication supplement, focusing on economical protection.

Structural Characteristics: Both sides of the bearing are equipped with seals, divided into contact seals (rubber sealing rings) and non-contact seals (iron dust covers), and both sides are completely closed to form an independent sealed space.Advantages and Disadvantages: The advantage is all-round double-side protection, which effectively blocks the intrusion of dust, water vapor and impurities, the lubricating medium is not easy to lose, the operation and maintenance cycle is long, and the maintenance-free period can reach several months to several years; the disadvantage is relatively high cost, after the sealed bearing is pre-filled with grease at the factory, it is difficult to supplement lubrication in the later stage, and the contact seal has a little friction and temperature rise during high-speed operation.Applicable Scenarios: Open-air equipment, dusty workshops, humid environments, corrosive medium environments, such as construction machinery, agricultural machinery, dust conveyors, outdoor fans, water pumps, etc. It is the first choice of sealing form for harsh working conditions.

Additional Tip: Non-contact seals are preferred for high-speed scenarios to reduce friction and heating; contact seals are preferred for heavy-load and harsh scenarios to improve protective sealing performance.