Ball Bearing Materials: Benefits & Shortfalls

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Selection of ball bearing material is a very important factor in the longevity and proper operation of your equipment and machinery. The most popular materials for ball bearings include steel, stainless steel, high-performance polymer (HPP), and ceramic. We will go over the benefits and shortfalls of each of these major materials, and identify the common industries and environments each are used in.

Steel

Steel material generally has high wear resistance and fatigue strength. It is the most common standard material for ball bearings used in manufacturing. With it’s strong strength at a very affordable cost, it makes sense that many applications will choose steel as the default material for most applications. However, steel is very susceptible to corrosion and rust, so it will not be a good choice in wet environments or near chemicals.

The best industries to use steel material in is general manufacturing, EV, warehouse automation, and packaging.

Stainless Steel

Stainless steel is an alloy of iron that is resistant to rusting and corrosion. It typically contains 11% chromium, which is the component that is providing its corrosion resistance. The luster and resistance to corrosion, are very common reasons for its selection in industrial applications. Although it still retains a fairly strong strength and wear resistance, stainless steel will generally have lower strength than steel due to its higher carbon content. (Wikipedia) With its corrosion-resistant properties, stainless steel would be an ideal choice of bearing material in wet or applications involving chemicals.

The best industry and environment to use stainless steel would be medical, laboratory, food, or general wet environments.

High-Performance Polymer (HPP)

High performance polymers (HPP) are plastics that meet higher requirements than standard or engineering plastics. HPP’s differ from standard plastics primarily by their higher thermal stability, outstanding chemical resistance, and superior product quality. (Performance Plastics) Common types of HPP include PEEK, PTFE (Teflon®), and UHMW. HPP bearings provide some of the strongest chemical resistances and allows usage of low-viscosity lubricants or no lubricant at all. Additionally, HPP bearings are electrical insulators and prevents the unwanted travel of electricity. The biggest shortfall of HPP bearings would be its reduced strength and allowable rotation speeds compared to its steel counterparts.

Some of the best industries to use HPP bearings would be semiconductors, medical, and various clean environments.

Ceramic

Ceramic bearings are comprised of ceramic rolling elements (balls) enclosed in a ferrous (typically steel) inner and outer race. (Emerson Bearing) Ceramic bearings are a fairly niche material choice for ball bearings, however, they provide great benefits including reduced weight, rolling resistance, thermal expansion, and typically being able to run without lubricant. One of the largest disadvantages of ceramic bearings would be its increased cost compared to the other materials and its lower load capacities.

Some common uses for ceramic bearings would be in electric motors, aerospace applications, performance racing vehicles, laboratory equipment, under water applications. (Boca Bearings)

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Works Cited

Boca Bearings. n.d. <https://www.bocabearings.com/general/full-ceramic-and-ceramic-hybrid-bearings#:~:text=Ceramic%20hybrid%20bearings%20are%20widely,ideal%20for%20ceramic%20hybrid%20bearings>.

Emerson Bearing. 2023. <https://www.emersonbearing.com/products/ceramic-bearings/#:~:text=Ceramic%20bearings%20are%20comprised%20of,often%20operate%20in%20hybrid%20capacities>.

Performance Plastics. 4 November 2021. <https://performanceplastics.com/blog/what-is-a-high-performance-plastic/>.

Wikipedia. 6 June 2023. <https://en.wikipedia.org/wiki/Stainless_steel>.

Most ball bearings are made of a type of steel known as high carbon chromium steel, often called chrome steel. This is used for reasons of cost and durability. Bearings are also made from other materials such as stainless steel, ceramics and plastic.

Chrome steel will corrode if exposed to moisture so, where corrosion resistance is needed, bearings made from 440 grade stainless steel are often used. This is a very hard, magnetic steel with good corrosion resistance but not suitable for use with salt water and many chemicals. 316 grade stainless steel is used for more corrosive applications but it is much softer so can only be used where loads and speeds are low.

Ceramics (zirconia and silicon nitride) are good for very corrosive or extreme temperature use while various types of plastic are suitable for good to very good corrosion resistance although only suitable for low load and low speed. 316 stainless steel bearings, ceramic bearings and plastic bearings are non-magnetic.

Got another question? Feel free to contact the SMB Bearings team directly on +44 (0) 1993 842 555 or sales@smbbearings.com.