Grade: A specific combination of dimensional form and surface roughness tolerance. A ball grade is designated by a grade number.
Deviation from Spherical Form: Determined by rotation of the ball
Lot Diameter Variation: The difference between the mean diameter of the largest ball and that of the smallest ball in the lot.
Nominal Ball Diameter: The diameter value that is used for the purpose of general identification of a ball size
Surface Roughness: Surface roughness consist of all those irregularities which form surface relief and which are conventionally defined within the area where deviations of form and waviness are eliminated. Determined by a stylus type instrument with the ball rotating.
