Thin Section Bearing Q&A

The image above shows the cross-section for a thin section bearing.

Thin section bearings are used in applications where space is limited or weight is an important design consideration. These motion control products appear thinner than standard ball bearings because their cross-section does not become larger as bore diameter increases. By helping to reduce space and weight requirements, thin section bearings can reduce costs for applications ranging from aerospace and defense to automation and robotics – just to name a few.    

This Q&A from Schatz Bearings of Poughkeepsie, New York (USA) provides answers to engineers’ frequently asked questions about thin section bearings. Schatz makes thin section bearings for bores up to 12” and in different cross-sectional dimensions. These motion control products are made of 52100 high carbon steel, 440C stainless steel, or CREN high nitrogen stainless steel and are available with ABEC 1F, 3F, 5F, or 7F tolerances. Sealed versions feature Buna-N molded seals.

Contact Schatz for more information.

How do thin section bearings differ from standard ball bearings?

With standard ball bearings, the width and thickness of the bearing increases in proportion to the bearing’s bore size. That’s not the case with thin section bearings because the cross section doesn’t change as the bore size increases. Because of this design, there is little change in the weight of a bearing even as the diameter of the application increases. This supports weight reduction efforts while requiring less space than a standard ball bearing would need.  

How thin is a thin section bearing?

As the table below shows, thin section bearings from Schatz belong to a lettered product series and have a cross-section with a specific dimension. Within each series, the cross section remains the same for all the different bearing bore sizes. 

Does a small cross section size make it a thin section bearing?

It’s not the size of the cross-section alone that matters. It’s about the relationship, or ratio, of the cross-section to the bearing bore. If the cross section doesn’t increase in proportion to the bearing bore in a series of bearings, then it’s a thin section bearing series.

Are there different contact styles for thin section bearings?

Yes. Thin section bearings can be radial, angular contact, or four-point contact bearings.

• Thin section radial ball bearings are used mainly with radial loads, but can also handle minimal axial, reversing, and moment loads.
• Thin section angular contact bearings are recommended for higher thrust and axial loads; however, these thin section bearings may also be able to handle radial and combined loads.
• Thin section four-point contact bearings have a raceway that creates four points of contact for handling moment and reversing loads. They are not recommended for radial or combined loads. This design is best suited to support axial (thrust) loads in both (reversing) directions.

What are the lettered types for thin section bearings?

Thin section bearings are A-type, C-type, or X-type products. These lettered designations correspond to the contact styles described above.

• A-type products are angular contact bearings.
• C-type products are radial contact bearings.
• X-type bearings are four-point contact bearings.

Are thin section bearings related to precision?

No. Some are high precision and others are low precision. The ABEC scale defines bearing tolerances and consists of numeric and alphanumeric classes. Because these classes range from largest to smallest tolerances, ABEC 1F thin section bearings have less precision than ABEC 7 thin section bearings. 

Are space and weight constraints the only reason to use a thin section bearing?

No. Thin section bearings can also reduce friction and prevent torque loss. Depending on the contact style, thin section bearings have plenty of load-carrying capacity. For example, the thin section four-point contact bearing that is used at the base of a robot’s arm can handle extreme moment loads at the base of the shaft.

What should you look for in a precision thin section bearing manufacturer?

Choose a bearing manufacturer who understands the importance of proper heat treating and quenching for thin section bearings. When a ring is heated, the manufacturer must hold it at temperature for a certain amount of time. The ring is then quenched, or rapidly cooled. This can put stress on the part and make the ring out-of-round or out-of-flat.

Schatz is an experienced manufacturer that makes thin section bearings and other types of specialty and precision bearings for a variety of demanding applications. Contact us to learn more.