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Definitions

Nominal Ball Diameter

The diameter value that is used for the purpose of general identification of a ball size; e.g. 1/4", 6mm etc.

Single Diameter of a Ball

The distance between two parallel planes tangent to the surface of the ball.

Mean Diameter of a Ball

The arithmetic mean of the largest and the smallest actual single diameters of the ball.

Ball Diameter Variation

The difference between the largest and the smallest actual single diameters of the ball.

Deviation from Spherical Form

The greatest radial distance in any radial plane between a sphere circumscribed around the ball surface and any point on the ball surface.

Lot

A definite quantity of balls manufactured under conditions which are presumed uniform and which is considered and identified as an entity.

Lot Mean Diameter

The arithmetic mean of the mean diameter of the largest ball and that of the smallest ball in the lot.

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 Tolerance

The maximum allowable deviation of any ball lot mean diameter from the Nominal Ball Diameter.

Specific Diameter

The amount by which the lot mean diameter differs from the nominal diameter, accurate to the marking increment for that grade.

Ball Grade

A specific combination of dimensional form and surface roughness tolerances. A ball grade is designated a grade number.

Ball Gauge

The prescribed small amount by which the lot mean diameter should differ from nominal diameter, this amount being one of an established series of amounts.

Ball Gauge Deviation

The difference between the lot mean diameter and the sum of the nominal diameter and the ball gauge

Surface Roughness

Surface roughness consists of all those irregularities which form surface relief and which are conventionally defined within the area where deviations of form and waviness are eliminated

Waviness

The more widely spaced circumferential component of surface texture.

Hardness

The measure of resistance to penetration of the ball surface or truncated flat of the ball by a specific indenting shape as determined by specified methods.

Case Depth

The distance measured radially from the surface of the ball to a point where the hardness becomes the equivalent of Rc 50. This term is applicable to case hardened balls only.

Passivation

A chemical treatment to remove corrodible surface impurities and to provide a protective film. This term is applicable to corrosion resisting balls only.

Techincal definitions