Bearings play an important role in the applications where there is rotary motion. They reduce the friction between two mating parts and hence adjacently save the power.
“Bearing is a mechanical element which locates two machine parts relative to each other and permits relative motion between them.”
Desirable Properties of Bearing Material
For the bearings to be effective, they should have the following desirable properties :
- Compressive strength
- Fatigue strength
- Corrosion resistance
- Thermal conductivity
- Cost and availability
The max pressure that is acting on the bearing is greater than the average pressure. Hence in order to withstand this maximum pressure, the bearing material should have high compressive strength.
In some applications, the bearings are subjected to high fluctuating loads. So to avoid fatigue failure, the bearing material should have sufficient endurance strength.
It is the ability of the material to form a strong bond with other materials. Generally strong bonds are formed with steel.
High capacity bearings are made by one or more thin layers of bearing material with high strength steel.
In the applications where there is a high working temperature, this temperature oxidizes the lubricating oil and forms the corrosive acids.
This formed acid attacks on the bearing material and corrodes it. So corrosion resistance property is also important in the case of bearing material.
- Selection of bearing according to Application
- Selection of bearing from the manufacturers’ catalog
- Different types of bearings
It is the ability of the bearing material to yield and adapt its shape to that of the journal.
It is the ability of the bearing material to embed small particles of dust, dirt, or abrasive particles without scoring the journal.
The dirt or dust particles in the lubricating oil may cause jamming in the clearance space. Hence the bearing material should have embeddability characteristics.
For the rapid dissipation of the heat, the bearing material should have high thermal conductivity.
Cost and Availability
The bearing material should have low cost and also it should be easily available in the market for its production.
One may think of, what materials of bearings are made of? What type of bearing materials are used for low speed applications.
Commonly used materials for the bearings are:
- Babbits (white metals)
- Copper-lead alloy
- Cast iron
- Aluminum alloy
- Sintered metal or porous metal
- Non-metallic materials.
These materials are discussed in brief in Materials for Sliding Contact Bearings.