Learn about Ball Materials

Learn about Ball Specifications 

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Balls are made in a large range of different materials. Some of the more common ones are listed here. Particular materials are chosen for their properties and the requirement of the application. However, the material properties also influence the quality of ball that can be produced, a factor which can make the correct choice difficult.

Carbon Steel (AISI 1010/1020)

Carbon steel balls are generally case-hardened with a soft core, giving resistance to shock loads and surface wear but with a limited load carrying capacity. For this reason, carbon steel balls of this type are generally used in applications where there are only moderate loads and slow rotating parts. This includes castors, drawer slides, and low precision bearings. They offer a significant cost saving as compared to chrome steel balls.

Chrome Steel (AISI 52100, 100cr6 SUJ2, EN31B, 1.3505)

AISI 52100 chrome steel was developed for the manufacture of bearings. It is very widely used and has properties optimised for the manufacture of bearing components. For this reason, balls manufactured from chrome steel represent the bulk of all precision ball production worldwide, and balls are available in the widest range of size and grade of any material.

Stainless Steel

Balls are manufactured in a number of stainless steel materials, and each has different properties and applications:

AISI 304

An austenitic stainless steel, AISI 304 is non-magnetic and has very good resistance to corrosion. The material cannot be hardened, other than by work hardening, and the balls are soft and susceptible to mechanical damage. They are used in applications where corrosion resistance outweighs the mechanical performance limitations.

AISI 316L

An austenitic stainless steel like AISI 304, it is non-magnetic and it can’t be hardened. AISI 316L has improved corrosion resistance as compared with 304. It is widely used within the chemical industry, food processing, and for medical applications. Finished balls are soft and can be machined by conventional techniques applied to stainless steel.

AISI 420

A martensitic stainless steel, AISI 420 is magnetic and hardenable. It is resistant to corrosion and can be used effectively in non-aggressive environments. Balls produced in AISI 420 are hardened to 50 to 56 HRC, which is slightly less than chrome steel, and can be used in place of chrome steel in all but the most severe applications.

AISI 440C

AISI 440C is a martensitic stainless steel similar to AISI 42o. It’s magnetic and hardenable. It offers the best combination of hardness and corrosion resistance available from steel and is widely used within the bearing industry for the manufacture of corrosion resistant bearings. Balls produced in AISI 420 are hardened to 58 to 62 HRC, the same as chrome steel, which it can replace in most applications.

Tungsten Carbide

Tungsten carbide, or more correctly cemented tungsten carbide, is a composite material in which hard ceramic particles (Tungsten Carbide) are cemented together with a metal binder. The properties of the material are a combination of the properties of the 2 constituent parts. Hardness and wear resistance is provided by the carbide particles, while the binder provides some measure of elasticity and shock resistance. Different binder materials and percentages can used to produce material with particular properties:

 Cobalt Binder

 Nickel Binder

Ceramics

 Alumina

 Silicon Nitride

 Zirconia

Other Materials

 Copper

 Phosphor Bronze

 Plastics