Steel Ball Grade Terms

- Jan 10, 2019-

Precision steel ball physical propeties (size, geometry, etc.) are critical, the way terms are used becomes critical. Even commonly used terms are often misinterpreted. To make sure everyone gets exactly what they want, we issue standarized explanations for some common ball terms,please check these as below.
Ball Diameter Variation: The difference between the largest and the smallest single diameter measurements of one ball.
Ball Grade: A specific combination of dimensional, form and surface roughness tolerances. A ball grade is designated by the grade number.
Basic Diameter: The size ordered which is the basis to which the "Diameter Tolerance" specification applies.
Basic Diameter Tolerance: The maximum allowable deviation of any ball mean diameter from the Basic Diameter, in any shipment to fill orders for that Basic Diameter.
Container Marking Increment: The standard unit steps, in millionths of an inch, used to express the Specific Diameter.
Deviation from Speherical Form: The greatest radial distance in any radial plane between a sphere circumscribed around the ball surface and any point on the ball surface.
Hardness: The measure of resistance to penetration of the ball surface or truncated flat of the ball by a specified indenting shape as determined by specified methods.
Lot: A definite quantity of balls manufactured under conditions which are presumed uniform and which is considered and identified as an entirety.
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 which is used for the purpose of general identification of a ball size, e.g. 1/4" 6mm, etc.
Passivation: A chemical treatment to remove corrodible surface impurities and to provide a protective film. This term is applicable to corrosion resisting balls only.
Specific Diameter: The diameter marked on the unit container, expressed in the grade's standard marking increment nearest to the mean diameter of the balls in that container.
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. (Lacking standarized practices in this field, the specifications and tolerances for waviness are subject to agreement between manufacturer and customer.)