or Tribology of a ball is critical to the surface-to-surface and/or surface-to-lubricant circumstances. Precision balls are required to have a better surface finish to ensure that the coefficient of wear is such that the ball has limited surface defects effecting the rotation of the ball as it passes through the bearing or other application. The better the surface finish, the less “noise” from vibration during bearing rotation. Surface finish can also be critical to providing a tight valve seal.
the better the grade of ball, the tighter the ball diameter tolerance: For example, an eighth-inch grade 3 ball has a diameter tolerance of ±0.00003, whereas an eighth-inch grade 200 semi-precision ball has a diameter tolerance of ±0.001. Diameter is critical for quiet bearings.