Analysis of the development of bearing sealing technology

The technical summary introduces a newly developed bearing that is equipped with sealing devices on both sides. These seals serve two main purposes: first, to prevent internal lubricant (grease or oil) from leaking out during operation, ensuring the bearing remains properly lubricated; second, to block external contaminants such as dust and harmful gases from entering the bearing cavity, thus protecting it from wear and damage. Common sealing materials include rubber, engineering plastics, and stamped steel (dust covers). The design of the sealing ring varies, and each type offers different levels of effectiveness. Sealing can be classified into two main types: contact and non-contact. In non-contact sealing, there is a small gap between the seal and the rotating shaft. A smaller gap improves sealing performance but limits the rotational speed. Conversely, in contact sealing, the seal directly touches the shaft, and a larger contact area enhances sealing but also restricts speed. Therefore, the choice of sealing method depends on the operating conditions. Research in sealing technology focuses on developing appropriate sealing solutions for various applications and ensuring compatibility between the seal material and the lubricant used. Bearings with integrated sealing have been in use for nearly four years. Initially, open bearings were common, but as industrial demands grew—especially in sectors like food processing, office equipment, and home appliances—there was a need for compact, lightweight designs that prevented water and air leakage. This led to the development of sealed bearings, which are now widely used in deep groove ball bearings and other types of rolling bearings. Globally, Japan's leading bearing manufacturers such as Seiko, Toyo, and Fujitsu have set the direction for sealing technology development. They have extensive experience and deep research in this field, with mature sealing technologies that have evolved from single-lip to multi-lip seals, and from contact to non-contact sealing. In China, similar progress has been made, with the development of sealed bearings including deep groove ball bearings, water pump bearings, railway tapered roller bearings, needle roller bearings, and cylindrical roller bearings. Among these, deep groove ball bearings have the highest output and widest application. However, according to recent inspections by the National Technical Bureau, Chinese sealed bearings still face issues such as poor sealing performance and significant grease leakage. Analysis shows that the main problems stem from unreasonable seal design, lack of sealing grooves on the inner ring, and low manufacturing precision. To address these challenges, future developments in China’s bearing sealing technology will focus on optimizing the seal structure for deep groove ball bearings, improving material properties for better wear resistance, heat resistance, and corrosion resistance, and extending the life of contact seals. Additionally, efforts will be made to develop high-temperature sealed bearings suitable for long-term operation at 120–180°C, as well as new structures like railway bearings. By 2005, the goal is to bring the sealing performance of these bearings up to the level of advanced international products from the late 1990s.

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