Deep groove ball bearings are a critical component in many industries, and their performance depends heavily on the effectiveness of their seal structures. A study by Liu Xingchun and Zhou Chunyu discusses the optimization of deep groove ball bearing seal structures to enhance sealing performance and reduce starting torque. This optimization also aims to streamline the manufacturing process and improve product commonality.
Problems with Existing Seal Structures
FIJ offers two types of double-sealed products: contact seals (-2RS) and non-contact seals (-2RZ, -2Z). The contact seals have a large starting torque, while the non-contact seals have poor sealing performance and are prone to grease leakage. These designs fail to meet the demands of the market and customers, particularly in the motor industry.
Before the optimization, the 6314 series, for example, used a simple straight-stage seal on the inner ring's outer diameter. This design required high precision in component processing and seal quality, and it had poor dust-proof and anti-grease leakage performance.
For the -2RS product, the rubber cover's inner bore and the inner ring's outer diameter had an interference fit, which resulted in a high friction torque but did not effectively prevent grease leakage.
For the -2RZ and -2Z products, the cover's inner bore and the inner ring's outer diameter had a clearance fit, leading to severe grease leakage that did not meet user requirements.
Furthermore, the bearing rings for these three structures were not interchangeable, requiring separate production and management for each order.
Optimizing the Seal Structure
The new design incorporates a slotted inner ring outer diameter, which significantly improves the seal's performance. The slots create a longer sealing path, making it more difficult for grease to leak out and for dust to enter.
Key features of the optimized design include:
The inner ring of the -2RS, -2RZ, and -2Z structures are now interchangeable and feature a slotted design. The slots have an inner angle of 7° and an outer angle of 20° to ensure manufacturability and manage grease overflow during high-speed rotation.
The inner ring slots act as a reservoir, storing small amounts of grease that may overflow during high-speed rotation.
The optimized -2RS and -2RZ structures have rubber covers that indirectly help block grease overflow.
The optimized design uses a clearance fit, which simplifies installation, boosts production efficiency, and reduces friction between the seal and the inner ring, thereby lowering the bearing's starting torque and energy loss.
Both the inner and outer rings of the -2RS, -2RZ, and -2Z seals are now universal and interchangeable.
Results of the Optimization
The optimized designs for the 6208-2RZ, 6210-2RZ, and 6314-2RZ products have passed rig tests at the Bearing Engineering Center. The grease leakage rate for the tested bearings was found to be below the standard value of 5%. The redesigned -2RS and -2RZ products meet the requirements for both contact-type seals (no grease leakage) and non-contact-type seals (low starting and friction torque). This has been particularly well-received by customers in the motor industry who are focused on energy conservation.
