Materials for ball bearing balls

The material for rolling bearing ball bearing balls varies widely and is always primarily oriented on the ring materials. This ensures that the interplay of cage, inner ring, and outer ring in the system is harmonised. This is especially important when the application involves heating or cooling the bearings. It is important that ball bearing running properties are always good. The most common ball materials are listed below with relation to the race material.

Balls for metal ball bearings

Roller bearing steel 1.3505/100Cr6

For these ball bearings, hardened steel balls are often used. The most often used material is a chrome steel with about 1% carbon and 1.5% chrome. The specifications of steel balls of martensitic chrome steel make them especially well suited to ball bearing production, since they make strong components that are resistant and convincingly durable in continuous operation. Balls made from rolling bearing steel are robust and durable. Susceptibility to corrosion tends to be low, so that cylindrical rollers and needle rollers are made of this material. But lubrication is indispensable.

Soda-lime glass

Glass balls are used when users require a metal-free ball bearing or a ball bearing with increased demands on chemical resistance. Soda-lime glass is used for bottles, drinking glasses and flat glass, and as a material for ball bearing balls. It has good chemical specifications suitable for ball bearings that are usually exposed to short-term chemical stress, but not to great thermal stress. Its light green colour has also given it the name lemon glass.
 

Borosilicate glass

This type of glass is much more expensive than soda-lime glass. Borosilicate glass is even more chemical-resistant than soda-lime glass, which means that it is used in applications involving strong acids. This type is clear and transparent.Other benefits:

• Very great resistance to heat and to changes in temperature
• Mechanical stability
• Low coefficient of linear expansion

Balls for ceramic ball bearings

Aluminium oxide Al2O3

Ceramic balls made of aluminium oxide, also known as oxide ceramics, have a polycrystalline structure. The specifications of the lightweight balls include good corrosion, abrasion and heat resistance. Despite influences such as water, salt solutions and some acids, they are extremely corrosion-free. It is important to avoid contact with hydrofluoric acid, hydrochloric acid, warm sulphuric acid and strong alkaline solutions. They are also known to be self-lubricating and electrically insulating. Balls made of Al2O3 aluminium oxide are white to ivory-coloured and are manufactured according to ASTM F 2094 Class II/III.
 

Silicon nitride Si3N4

Balls made of the ceramic material silicon nitride are light, but offer high toughness and excellent corrosion resistance. Corrosion only occurs in certain acidic and alkaline solutions. The material has an insulating effect. The balls are also self-lubricating and have great resistance to temperature fluctuations, which noticeably affects the bottom line. They are much more expensive than balls made of aluminium oxide. Balls made of Si3N4 are a black mother-of-pearl colour.
 

Zirconium oxide ZrO2

Balls made of zirconium oxide are particularly suitable in application environments where high temperatures, corrosion and abrasion play a role. They are significantly lighter than aluminium oxide balls.

Other benefits:

• Very low porosity of the material
• Extreme hardness of the balls
• Very good thermal, chemical and mechanical resistance