Do sealed bearings still need lubricating? methods for sealing bearings

Do sealed bearings still need lubricating? methods for sealing bearings

Do sealed bearings still need to be relubricated?

No. Bearings with seals on both sides (whether rubber seals or stamped steel seals) do not require relubrication.

To ensure the bearing achieves its *optimal service life*, the grade of grease to be used and the amount to be filled have been determined through countless practical experiments to provide the *best* and *most scientific* solution. It is generally accepted that the service life of the grease is equivalent to that of the bearing. Furthermore, the design of the seals—including their distance from the inner ring, whether they are in contact, non-contact or labyrinth-type—has been carefully engineered. Removing and refitting the seals during greasing will inevitably compromise their effectiveness, thereby affecting the bearing’s service life.

What are the methods of bearing sealing?

Sealing methods for rolling bearings can be divided into two categories: contact seals and non-contact seals. A ‘self-sealing bearing’ refers to a bearing that is manufactured with built-in sealing features, such as dust caps or sealing rings. This type of seal takes up very little space. An ‘external bearing seal’ refers to a sealing device with various functions that is incorporated into the interior of components such as end caps.

1. Contact seals include felt ring seals and O-ring seals, amongst others.

2. Non-contact seals include axial curved-path seals, radial curved-path seals, oil groove seals and retaining ring seals, amongst others.

Bearings within this service life should exhibit initial fatigue damage (spalling or pitting) on any of their bearing rings or rolling elements. However, it is clearly evident, both in laboratory tests and in actual use, that bearings with identical appearances under the same operating conditions can exhibit vastly different actual service lives.

Furthermore, there are several different definitions of bearing ‘service life’, one of which is the so-called ‘operating life’. This refers to the actual service life that a bearing can achieve before failure, where such failure is typically not caused by fatigue but rather by wear, corrosion, seal failure and other factors.

A bearing seal, a type of bearing sealing element, and in particular a ball bearing seal, comprises a circular ring with two circular projections extending upwards from one end face; the inner diameter of the smaller projection mates with the outer diameter of the ball bearing’s inner ring, whilst the larger projection mates with the outer diameter of the ball bearing’s ball ring; the inner bore diameter of the seal is not less than that of the inner ring of the ball bearing. It is characterised by its ability to prevent grease fires, eliminate the need for frequent relubrication and its simple structure. It is widely used in bearings.

A bearing seal, characterised in that: two circular projections extend upwards from one end face of a ring-shaped body; the inner diameter of the smaller projection mates with the outer diameter of the inner ring of the ball bearing, whilst the larger projection mates with the outer diameter of the ball cage of the ball bearing; the inner bore diameter of the seal is not less than the inner bore diameter of the inner ring of the ball bearing.