Did you know that the humble ball bearing is one of Leonardo da Vinci's inventions? His helicopter design may have been a fail, but the ball bearing was a successful component of it.
Today the ball bearing is an integral part of technology. It reduces the level of friction between the two components. To ensure optimal functioning though, it is vital to select the right bearing material
There are a few common materials that most bearings and their housings are made from.
Steel
Steel is used most often for making the housing for bearings. So it makes sense that it is also used for the bearings.
For steel to be the most effective it needs to be heat treated. Here at Miheu we are the largest Slovenian provider of heat treatment.
We know the importance of properly heating steel to the right temperature and then quickly cooling it. By being in control of the complete production process we can ensure only high-quality steel reaches our clients.
Types of Heat Treating
There are a few different methods for heat treating steel. The method used will depend on what the steel's intended purpose is.
Annealing will heat the metal but then cool it slowly. This softens the steel.
Carburizing deposits a layer of carbon on the surface of the metal. This is done through applying high heat and a carbon-rich material.
Case hardening is going to carburize the metal and then cool it quickly. the center of the steel stays soft while the outside hardens.
The opposite of carburization is decarburization. This removes the carbon either by heat or an oxidation process.
The process of nitriding adds nitrogen to the surface of the steel. This is done by applying heat and exposing it to nitrogen-rich liquid or gas.
Advantages
Steel gets used so often because it is capable of performing under high loads. It can sustain high rates of rotation and not experience deformation.
A high level of carbon and chromium content is what helps steel bearings perform under the toughest of conditions. The higher levels of these two metals in steel require it to be heat treated.
Heat treating also serves another purpose. It allows steel bearings to withstand temperatures of up to 120 degrees.
Disadvantages
The downside of steel is that the chromium content makes it susceptible to corrosion from chemicals. This is important to keep in mind as prolonged exposure to moisture or acid compounds will lead to failure.
To combat the corrosive properties, opt for a higher chromium stainless steel. If it is at least 18% it will resist corrosion better.
The bearings can also be loud while in operation.
Finally, these types of steel are unsuitable in a medical environment where there is an MRI in use. This is because the steel has magnetic properties.
Ceramic
Because steel is not ideal for certain applications, ceramic bearings are an option. They work well in environments where there is chemical processing, food, or pharmaceuticals.
Advantages
Ceramic bearings that contain a silicon nitride have low expansion rates from heat, a smooth surface, and are extremely hard. They also resist corrosion and have a low electrical conductivity ability.
Another advantage is that they require little to no lubrication. This allows for cleaner operation. The difference is most notable by the low heat production at high speeds due to lower friction.
Disadvantages
Ceramic bearings do not have the same load capacity as their steel counterparts. They are also sensitive to thermal shock. You'll know your bearings have experienced this when you see cracks.
Ceramic bearings tend to be the most expensive option.
Plastic
Thanks to modern science and technology plastic is now a widely used material for industrial applications. Plastic bearings are lightweight, not magnetic, not conductive, and corrosion resistant. They also have a high load capacity.
The plastic used to make the bearings can be a wide range of materials. Here are some of the more common plastics used:
- polytetrafluoroethylene (PTFE, Teflon)
- general polyamide (PA6/66)
- phenolic impregnated fibers
- polyoxymethylene (POM-C)
- polyvinylidene fluoride (PVDF)
- polyetheretherketone (PEEK)
Advantages
Plastic bearings are a good option because they resist wear thanks to the self-lubricating abilities. They can also maintain their shape and function in temperatures up to 150 degrees.
Their operation is quiet and smooth because of their low friction qualities.
Disadvantages
Plastic bearings are susceptible to high heat though. High loads are also a problem for them. If they are exposed to either of these things there is a risk that the bearings will deform.
Don't Forget the Cage
It isn't enough to only choose the right material for the bearings. You also need to choose the right material for the cage.
The most common material used for the bearing housing is steel, followed by plastic. Plastic cages work well in applications that require low torque and high speed.
Here the motion is fast but there isn't a lot of pressure or pull on the bearings. Plastics cages are also cheaper to manufacture.
Steel cages will be used with steel bearings in applications that require a high load application.
Choose a Bearing Material
When choosing a bearing material, it isn't enough to choose the right material. You also need to ensure that you source them from the right manufacturer.
A quality manufacturer will take the time to have a complete production process. This ensures that the bearings you use will perform as you expect them to.
If you are unsure of the bearing material that is right for your needs, it is best to discuss with the professionals. An experienced manufacturer will be able to point you in the right direction.
View more information here about our line of bearing housings that are heat treated and machined with the utmost precision.