Based on the above performance requirement, sealed structural design elements with high speed, high and low temperature resistance, resistance of mud-proof, dust-proof, oil-proof and low starting torque and high performance rubber sealing ring. Design of non-contact, light contact, contactless and contact type 4 form of the seal. Since tested-contact seals large starting torque, and wear a more serious, do not apply to FAG automotive alternator bearing the seal of high temperature, high speed, durability requirements and is not described.
　　1, non-contact (gap):
　　Non-contact (Figure 1) the sealing lip and the FAG bearing inner ring are the radial and axial clearance fit, the gap value is 0. 02~0. 06mm, its characteristic is due to the lips, no contact with FAG bearing inner ring, so the starting torque is very small, and lip wear is not a problem. But the FAG bearings radial and axial clearance of the sensitivity is a strong, prone to side gap leakage caused by too large, it would be inappropriate to use.
　　2, light-contact:
　　Features similar to a gap-type seal of light-contact, exposure of the lip and the inner ring is 0. 05~0. 12mm, also have lower starting torque and better abrasion resistance, but because fibrillation FAG bearing clearance and work, you cannot meet the requirements for water resistance.
　　Secondary contact:
　　Medium-contact with the inner ring of the degree of interference is normally 0. 15-0. 25mm, in such conditions, the lip and the radial axis contact force is moderate, seals of various specifications are in good form, moderate interference can eliminate clearance, vibration, the FAG bearing seal lip sealing effect. Its high speed, high and low temperature resistance, resistance-and mud-proof and dust-proof oil low starting torque and best performance.
　　Determination of interference:
　　Interference with FAG bearings inner ring with sealing lip diameter size difference between the axle head and shaft, is the most important parameter of the seals, reasonable interference is a requirement for seals with a good performance, it can produce radial forces and compensate the eccentricity of the shaft. Had Ying volume had small is contact force smaller, axis and lip mouth cannot formed good of tie, not conducive to oil film of formed, and after a time of work, will make lip mouth occurred must volume of wear, caused outside slurry of invasion people and grease of leaked, led to sealed pieces failure; and had Ying volume had large, is radial force and two lip mouth and axis shoulder of contact stress variable large, had large of stress will make lip mouth Xia of oil film failure, led to axis and lip produced dramatic of friction, make sealed pieces fast wear, lip mouth variable large and failure. After a lot of testing and simulation, interference is set at 0. 15mm。