The fundamental dynamic load rating is the maximum load that a bearing may potentially withstand for one million rotations. For radial bearings, this is stated as pure radial load, while for thrust bearings, it is expressed as pure axial load. Radial and axial loads should not be considered separately; instead, they should be added together to obtain the total bearing load.
For example, if a bearing has a radial load capacity of 500 lb and an axial load capacity of 100 lb, its total dynamic load rating is 600 lb. Bearings are usually labeled with their single-load-capacity value, but it's important to know that they can carry more than just those two types of loads.
Fundamental dynamic load rates It typically measures the maximum load that a bearing can withstand at room temperature while the sliding contact surfaces are in motion. In every specific application, the maximum allowed load should always be assessed in connection to the intended rating life. For example, if you plan to operate the motor continuously for 1000 hours, then it should be capable of withstanding a maximum load of 100 kilo-loads (22,000 pounds). If the application requires operation at higher speeds and/or temperatures, then heavier bearings may be required.
The maximum load capacity of a bearing depends on several factors such as material strength, surface treatment, lubrication, heat generation and other bearing parameters. Generally, the higher the speed range will be used, the stronger the material needs to be. That is why some bearing manufacturers increase the load capacity by using stronger materials in their designs.
For example, if you want to use a bearing for a spindle that will be turned at high speeds and subjected to heavy loads, then you should get a bearing that has been designed for such applications. These types of bearings are usually made from stainless steel or carbon steel and often include an outer ring, two or four ball bearings and a housing to hold them all together.
The basic rated life (90 percent dependability) of bearings running at fixed constant speeds is indicated in total operating hours. A bearing that has been tested to meet or exceed this standard is called a high-speed bearing.
Bearings used in high-speed applications must be designed to handle higher loads than those used in low-speed applications. For example, if a bearing is designed to operate at 10,000 rpm, it can support two times its own weight (20,000 lb) as long as it is kept under 2,000 pounds pressure (9,540 N). If the bearing starts to spin faster, it will need more powerful magnets to hold it in place. As long as the magnets are strong enough, the bearing can still handle much higher speeds.
There are two types of high-speed bearings: ball and roller. Ball bearings offer greater capacity and longer life when compared with their metal-on-metal counterpart, the roller bearing. However, they require proper lubrication to work effectively. If not used properly, high speed bearings can fail due to overheating, magnetic attraction failure, or excessive vibration. Excessive vibration can occur when there is not enough dampening in your housing or transmission system to absorb these high speeds.
The dynamic load rating (C) of a radial or angular contact ball bearing is the estimated, continuous radial load that a collection of seemingly identical bearings can potentially withstand for one million revolutions. The dynamic load rating is simply a guideline. In actual use, radial bearings are expected to with stand much higher loads than those specified by their manufacturer.
A radial roller bearing has an outer ring, an inner ring, and several rows of balls positioned between the two rings. When used as a radial load bearing device, these balls act like little rollers that allow movement in each direction but prevent rotation. A shaft can be placed inside the holes of the outer ring or outside the holes of the inner ring; both are acceptable design choices. As long as there is some way to keep the balls separated so they do not touch, then they can bear load in both radial and axial directions.
There are two types of radial ball bearings: single-row and multiple-row. Both have similar construction, but the number of rows of balls varies between them. In a single-row bearing, only one row of balls is used. This is the most common type of bearing when just a small amount of force is needed to support heavy loads. Multiple-row bearings contain several rows of balls separated by tiny gaps. These bearings are more suitable when high load capacity and smooth operation are required.
The Basic Dynamic Load Ratio, or "dynamic capacity," of a ball bearing is the estimated, constant radial load at which a collection of seemingly similar bearings with a stationary outer ring can statistically withstand one million inner ring rotations. This means that if you loaded a set of four identical ball bearings so that each one resisted this constant radial load, then they would remain intact and continue to operate for as long as possible before one failed.
This is usually expressed as a percentage of maximum load capacity. For example, a bearing that can carry a radial load of 100 lb for an hour (50% dynamic capacity) would be able to support a peak load of 200 lb for 10 minutes (100% total capacity). A bearing that can stand up to 300 lb-radial load for an hour would be suitable for applications where peaks of up to 600 lb were expected over an hour's use.
Ball bearings are not designed to handle large amounts of axial load. Such loads cause excessive wear on the balls and their raceways. Also, since there is no way to prevent such loads from occurring, we should avoid putting them in situations where they can happen.
When you use the term "dynamic load" it refers to the amount of load that changes direction rapidly. In other words, it's a load that is both radial and angular.