What are ball bearing manufactured from?
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.
Main Materials of Ball Bearing
The main material for making ball bearing:
- 440 stainless steel
- 316 stainless steel
Ball Bearing with Materials
Steel Ball Bearings
Partly because they are an older technology, steel ball bearings are a trusted solution for many design engineers. Typically, these types of bearings are comprised of all-steel parts, but are available with different types of steel races and balls, or with a phenolic cage.
Steel ball bearings are ideal for robust applications handling extremely high loads and fast rotations per minute (RPMs), and some feature a radial load capacity of up to 30,000 pounds. Another advantage of steel ball bearings is that they tend to be very precise due to the clearance that can be achieved during the manufacturing process.
Ceramic Ball Bearings
The most common type of ceramic ball bearing is often considered a “hybrid”, which indicates that the outer race, inner race, and cage of the bearing are comprised of steel, while the balls are made from ceramic. Fully ceramic ball bearings tend to be more corrosion resistant, more rigid and lighter in weight than most steel ball bearings.
Lower coefficients of friction and higher RPMs are also possible and, since they are non-conductive, ceramic ball bearings can be used in electrical applications. In addition, most ceramic balls bearings can operate in temperatures up to 1,800 ̊ F.
Plastic Ball Bearings
While plastic ball bearings are a newer technology, they have advantages that are not offered by steel or ceramic ball bearings. Plastic ball bearings are comprised of all-plastic races and a plastic cage, and are typically available with a choice of three different types of balls: plastic, glass or stainless steel. The choice of material is often dependent on the environment in which the bearing will be used.
The most common ball material within a ball bearing is stainless steel. Stainless steel balls are the most cost- effective choice, but they are heavier than both the plastic and glass options, and they are magnetic, which can be a detriment to some applications. Glass balls are ideal when a metal-free solution is needed. Glass balls also o er excellent chemical resistance and weigh less than the steel balls. Plastic balls are another ideal option. They weigh less than both the steel and glass balls, and o er excellent wear resistance while still being resistant to a wide variety of chemicals. Still, there are instances where plastic ball bearings should not be used, including applications with high loads or long-term temperatures exceeding 300 ̊ F.