Metal Ball Definitions

Ball Grade – A specific combination of dimensional form and surface
roughness tolerance. A metal ball grade is designated by a grade number.

Basic Diameter – The size ordered which is the basis to which the
basic diameter tolerance applies.

Basic Diameter Tolerance – The maximum allowable deviation of
any metal ball mean diameter from the basic diameter, in any shipment
to fill order for that basic diameter.

Case Depth – The distance measured radially from the surface of the
metal ball to a point where the hardness becomes the equivalent to Rc50. 
This term applies exclusively to case hardened balls.

Deviation from Spherical Form (roundness or sphericity) – The greatest
radial distance in any radial plane between a sphere circumscribed around
the metal ball surface and any point on the ball surface.

Ferritic Stainless Steel Balls – Ferritic stainless steel balls are
manufactured from the second most common classification of stainless
steel, about 25% of total stainless production. Ferritic stainless steel balls
are made from steel with at least 10.5% chromium content, but no
significant nickel content. The lack of nickel means ferritic materials have
lower corrosion resistance than austenitic (chromium-nickel) stainless steels.

Ferritic stainless steel balls are best suited for general and high-temperature
applications rather than service that requires high strength. In addition to
balls, ferritic stainless steel is used in automotive trim and exhaust systems,
interior architectural trim, and water tanks. The most common ferritic
stainless steel that is used to manufacture precision balls is 430 stainless steel.

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

Lot – A defined quantity of metal balls manufactured under conditions which
are presumed uniform and which is considered and identified as an entirety.

Lot Mean Diameter – The arithmetical mean of the mean diameter
of the largest metal ball and that of the smallest ball in the lot.

Lot Diameter Variation – The difference between the mean diameter
of the largest metal ball and that of the smallest ball.

Mean Diameter of a Metal Ball - The arithmetical mean of the largest
and the smallest single diameters of the ball.

Metal Ball Diameter Variation – The difference between the largest
and the smallest single diameters of one ball.

Miniature Balls – These are less than 1/8" (3 mm) in diameter.

Nominal Metal Ball Diameter – The diameter value that is used for
the purpose of general identification of a ball size.

Passivation – A chemical treatment to remove corrodible surface
impurities and to provide a protective film. This term is applicable only
to corrosion resistant metal ball varieties.

Specific Size – The amount by which the lot mean diameter differs
from the nominal diameter.

Single Diameter of a Metal Ball – The distance between two parallel
planes tangent to the surface of a ball.

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.

TrimRite^® – a hardenable martensitic stainless steel ball material.

TrimRite is a registered trademark of CRS Holdings, Inc., a subsidiary of Carpenter Technology Corp.

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