Global Precision Ball & Roller
178 Sunny Valley Road
New Milford, Connecticut 06776


Technical Specs

Key Terms and Definitions

Annealed: A metalgraphic process in which a ball is softened. An annealed ball can be ground, drilled, filed and welded. Heated to remove or prevent internal stress; free from internal stress by heating and gradually cooling; toughened or tempered.

Ball Diameter Variation: The difference between the largest and the smallest actual single diameter of one ball.

Ball Gage: 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. A ball gage, in combination with the ball grade and nominal ball diameter should be considered as the most exact ball size specification to be used by a customer for ordering purposes.

Case Depth: A distance from the surface of the ball to the unhardened core. It is measured radially from the surface to a point where carbon content or hardness becomes the same as the core.

Container Marking Increment: The standard unit steps in micrometers or in microinches, used to express the specific diameter.

Deviation from Spherical Form: Determined by rotation of the ball against a linear transducer with less than 4 grams of force. The resulting polar chart is interpreted using the minimum circumscribed circle method (MCC) per ABMA std. 10.

Flashing: A process that gives a ball blank a rough finish and removes the excess material around the ball.

Grade: Specific combination of dimensional form and surface roughness tolerance. Ball grade is designated by a grade number.

Grinding: A process in which balls are polished or smoothed with a grinding wheel to make a ball a smaller size.

Hardness: The measure of resistance to penetration of the ball surface or truncated flat of the ball by a specific indenting shape.

Heading: A process that produces slugs from raw wire or rod material through cold forging.

Heat Treating: A high temperature process that hardens the ball by subjecting a metal or alloy to controlled heating and cooling to improve hardness and other properties.

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, e.g. 1/4”, 6mm, etc.

Nominal Ball Diameter Tolerance: The maximum allowable deviation of any ball by a specific indenting shape.

Passivation: A process in which balls are dipped into acid to clean off any leftover metal shavings; a treatment to render the surface less reactive chemically.

Polished: A process in which a ball is put into a lapping machine and tumbled to improve the finish.

Specific Diameter: The mount by which the lot mean diameter differs from the nominal diameter, accurate to the container marking increment for that grade. The specific diameter should be marked on the unit container.

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. It is determined by a stylus-type instrument with the ball rotating. Compliance with Ra limits specific in ABMA Std. 10.

Waviness: The more widely spaced circumferential component of surface texture.

Helpful Downloads

ISO 9001: 2015 Quality Certification. Download PDF.

AFBMA Grade and Tolerance. Download PDF.

International Standards Organization 3290 Grades/Tolerances for Steel Balls. Download PDF.

ISO 9001: 2015
ISO 14001: 2004
ISO TS 16949: 2009

178 Sunny Valley Road, New Milford, Connecticut 06776
Tel: 860-210-0808 | Fax: 860-210-0818 | Email:

Home       Our Quality Products       Market Applications       About Us       Technical Specs      Manufacturing Process      Testimonials      Commentary       FAQs