The development of bearings, bearing materials, and lubrication have taken place over centuries in incrementally small steps. A typical standard bearing has dimensions and ratings which are universal, while the ISO standards have created a worldwide commonality for design.
It is important to understand that basic bearing dimensions are time tested and manufacturers’ ratings for loads and speeds can be steadfastly relied upon for design purposes.
It would be most suggested to use a standard bearing when possible, to take advantage of the economy’s scales in manufacturing. As a rule, there are certain bearing sizes within a series of bearings where bearings are manufactured in such volume that the price should be a leading design consideration. For example, the 6200 series bearing part number 6203 has the dimensions of 17mmx40mmx12mm. The 6203 bearing is highly produced and is used in numerous applications making it an attractive candidate when designing. If your design can be accommodative, then you would choose this bearing over the nearly identical 6202 size measuring 15mmx35mmx11mm, which does not have the scale of production and cost advantages of using a 6203 bearing.
Designs and applications of custom bearings
For bearings, it is a good idea to never attempt to change envelope dimensions due to the relationship between outer race, inner ring, and rolling elements. Centuries of development have proven the standard design to meet certain speed, load, and life results.
Certain applications and conditions will require the customizing of standard bearings, with the benefits for customizing bearings being to achieve optimal performance and life.
One of the most common changes or selections to customize bearings is to adjust the internal radial clearance. Clearance in the bearings can be changed in manufacturing to accommodate the designer’s requirement for fit and function.
Changing ball size and number can be a practical way to increase load or increase speed depending on the direction of the sizing.
Lubrication is an area with major consequences to the user. Selecting the correct lubrication can increase life and functionality. The primary role of bearing lubrication is to place an oil film between all rolling or sliding surfaces. When customizing your bearing you will need to do research on the best lubrication for your application. Speed ratings are also affected by anywhere from 25-50% depending upon the lubrication selected.
Custom bearing design features can include changes to the raceway curvature, ball size and material, ring material, and ring design, which can include flanges and extended inner rings.
Sizes and materials
Custom bearings can be hybrid in design where the rings are usually manufactured from AISI 52100 chrome steel, or 440C stainless steel. In combination with these standard ring materials is the use of ceramic balls. There are many benefits in using Hybrid bearings, which include no or little lubrication, lighter weight, and higher speeds. Hybrid bearings are commonly used in machine tool spindles.
Hybrid bearing ceramic balls
In most instances, you will want to start your design using a standard bearing and then add or change elements to create the best solution for your application. Standard bearings can be improved to increase speed ratings by 10% when specifying ceramic balls. Another 10% can be achieved when increasing the precision rating. For machine tool bearings, increasing the precision from ABEC 7 to ABEC 9 is commonly done to increase the speed rating. Work with your supplier to help with these calculations.
Still have a question or need to discuss something? Contact us to get help.