Materials & Heat Treatment
 ferrule
  (1) Without flange. Bearing steel GCR15, solid quenched, MRC (hardness) 58-62.
  
 (2) Flange. 55, 655MN, etc., case quenched, MRC (hardness) 58-64.
  
 Rolling elements
  
 (1) Balls. Bearing steel GCR15 integral quenching, MRC 58-64.
  
 (2) Rollers. Ditto.
  
 Cage
  
 (1) Engineering plastics: nylon + 25% glass fiber, lighter, less centrifugal force.
  
 (2) Metals: steel, copper, aluminum, alloy, heavier, centrifugal force is larger.
  
 Seals
  
 (1) Single lip. Friction, waterproof, dustproof.
  
 (2) Lips. Friction, waterproof, dustproof.
  
 (3) Card type. Friction, waterproof, dustproof.
  
 Three sealing methods, increasing in an incremental manner
  
 tolerance
 Without flanges. Similar to ordinary bearing class 0
  
 Flanged. Splines, flanges
  
 Surface roughness
 Same as class 0 bearing, mating surface Ra 2.5μm
  
 Clearance
 (1) Radial clearance. Inner and outer ring matching time: calculate α (contact angle), R (distance between two channels), DN (steel ball), etc.
  
 (2) Axial clearance. When using, GB 0.07-0.1mm or according to customer's requirements.
  
 Residual magnetism
 vibration
 (1) Speed (standard), rotational speed, high, medium and low wave (there is no standard for classification, roughly three frequency bands), standard ZV1~ZV4
  
 (2) Acceleration, rotational speed, high, medium and low wave, standard Z1~Z4
  
 Appearance quality
 Cracks, rust, bumps, black skin
  
 life span
 (1) Simulation experiments. In-plant testing machine (accelerated)
  
 (2) Endurance test. Wild land in the factory (cold, heat, humidity, drought)