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Tel: 860-571-3602  |

Rolling Elements

Rolling elements are either balls or rollers. Rollers offer higher load carrying capability (theoretically, a line of contact vs. point of contact for a ball).


Retainers are used to hold rolling elements (balls or rollers) in proper orientation so they do not all bunch together. Typically made from stamped metal or molded plastic.

Bearing Cages

Bearing cages, also known as bearing separators, are used to hold rolling elements (balls or rollers) in proper orientation so they do not all bunch together. Typically made from stamped metal or molded plastic.

Bearing Races

Bearing races, also known as bearing rings, are typically produced using high quality bearing grade chrome steel, which is valued for its superior mechanical properties (tensile strength, hardness, wear resistance).  Precision machining and grinding processes are used to fabricate these components, which must withstand high speeds and loads during operation.


“Shaft” is typically used to describe the long narrow portion of a more complex cylindrical component or even a cylindrical part that been turned or machined.  Some customers use the term shaft to describe even basic parts that most people would label as pins or rollers.


“Needle” or “needle roller” implies that the length is significantly longer than the diameter.  The part is acting as a rolling element.


“Dowel” is often used in conjunction with “pin” and is often used as a detent or to closely align or support parts.  A detent is used to prevent or resist movement until it is released.


“Roller” implies that the part moves (rolls) when in use.  Generally a roller is acting as a bearing, supporting a load along its outer diameter.


“Pin” is generally used to describe a mechanical component that acts as a fastener to join other parts together in an assembly.  A pin may act as a pivot, hinge, jig, fixture or shaft.  A jig is typically used to hold a work piece in place and/or guide a tool operating on the device.  A pin is often used to locate or hold parts.  Some pins are headed; others are not.

DIN 5401

A ball standard commonly used in Europe.

ABMA Standard 10

A ball standard, formerly known as AFBMA, commonly used in the USA.

ISO 3290

A ball standard, recognized around the world.

Grade 1000 Balls

Grade 1000 balls are used in applications where balls produced from the finest steel are needed but wider tolerances are permissible.

Grade 100 and 200 Balls

Grades 100 and 200 balls are suitable for commercial ball bearings, heavy duty conveyors, lawn mowers, etc., where high quality steel is needed but where the accuracy of Grade 25 is not essential.

Grade 25 Balls

Grade 25 balls are usually specified for precision ball bearings, accurate valve applications or quality purposes.

Grade 10 Balls

Grade 10 Balls are used where extreme high precision is required.

Diameter Tolerance Per Shipment

The maximum permissible deviation of any ball diameter in any shipment from the basic diameter ordered.

Diameter Tolerance Per Unit Container

The maximum permissible range of the average diameters of the largest and smallest ball within the unit container.

Surface Roughness

A measure of the average deviation of a surface from its ideal form.  There are many different roughness calculations; the most common is Ra, which is the arithmetic average of the deviations in profile height from the mean line representing the nominal surface, with all of these deviations expressed as positive numbers.  Roughness is typically measured in microinches (millionths of an inch) or microns.


Also known as roundness/Diameter Tolerance. The permissible difference between the largest and smallest diameter measurable on one ball.


A measure of the overall precision of the ball.  Incorporated in the concept of grade is diameter tolerance, sphericity and surface roughness.  The lower the grade number, the more precise the ball.  For example, a grade 25 ball is more precise than a grade 100 ball.


The geometric refinement, other than sphericity, on the surface.

Visual Inspection

The macroscopic inspection of the surface for defects.

Ball Waviness

The geometrical irregularity of the surface with wave lengths longer than roughness.

Ball Roughness

Surface irregularities, the height, width and direction of which establish the predominant surface pattern.


The measure of resistance to penetration.  There are several different scales (e.g. Vickers, Rockwell C, Rockwell B, Rockwell 15N, Rockwell 30N, etc.) that are commonly used.  Conversion tables to compare a value on one scale to another scale are readily available.  For steels, there is a strong correlation between hardness and tensile strength.

Mechanical Properties Crushing Strength

The measure, in pounds, of the resistance to crushing loads.

Specific Diameter

The diameter marked on the unit container, expressed in the grade's marking increment nearest to the average diameter of balls contained.

Basic Diameter

The size base to which tolerances apply, e.g., 1/4" + .0002, or .2502.

Ball Diameter Size

The size used for purpose of identification, e.g. 1/16", 1/8", 1/4", 1/2", 2mm, 5.5mm, etc.