To fully understand ball bearings, it’s important to know how they work. Ball bearings are relatively simple structures that can carry different load weights depending on their internal structure.
The bearings act much like airplane wheels during taking off. At first, all of the pressure is on the wheels. As the plane gradually becomes airborne, the wheels take less of the pressure. The same holds true for ball bearings. Much of the weight is placed on the balls when an application first begins moving. Once it is in full operational mode, the weight on the bearings lessens.
What is inside a ball bearing?
Not surprising, metal balls and rings. They are comprised of:
- An outer ring, which has a raceway on the underside of the ring.
- Balls which can be in cages like the image below. The cage signifies that it’s a standard ball bearing. Bearings that have loose balls between the inner and outer rings are known as a full complement ball bearing.
- Inner ring
What is the difference between a full complement ball bearing and a standard ball bearing?
A standard ball bearing has a cage to separate the ball elements. A full complement ball bearing doesn’t have a cage around the balls.
A full complement ball bearing has higher load rating and service life than a standard ball bearing of the same size. It has lower limiting speed and is normally used in low speed and heavy load application.
When should a roller bearing be used over a ball bearing?
To determine the optimal bearing, the following must be considered:
- Direction of Load
If the envelop dimensions are the same, the load rating of a roller bearing is much higher than a ball bearing. This means that the service life of a roller bearing will be much higher than a ball bearing. Of course the cost for a roller bearing is higher than a ball bearing if they are similar sizes. Generally, for a very heavy load at low speed, a roller bearing is preferred.
The advantages of ball bearings over roller bearings are: low cost, low noise, high speed limit and low rotational torque. A ball bearing is always the first choice if it can meet your application. For an application with a high speed and normal load, ball bearings are ideal.
Applications that have a high speed and high load typically use a four-point contact bearing and grease to cool down the bearing during use.