3 tips in choosing plain bearing dimensions correctly

 

In many occasions, surrounding factors such as housing hole, shaft, and other elements predetermine what plain bearing dimensions are chosen. Then, depends on the price or availability, a bearing with a length of 10mm or 12mm is selected. However, what if these factors delimit the choice of bearing tightly that a special part is needed? There are some pitfalls, which can be avoided if sensible design decisions are made.

Here are 3 tips on how to choose the right plain bearing dimension.

Thin-walled plain bearings – Choose suitable materials and manufacturing methods

Plain bearing dimensions that result in wall thicknesses of less than 1mm or even 0.5mm are difficult to make, depending on the other dimensions. In the case of metal plain bearings, therefore, the dimensional stability and availability of metal sheets decides whether the bearings can be manufactured. In the case of polymer plain bearings, in contrast, the design and the reliability of the injection mould process are decisive. Unfavourable combinations of long bushings and relatively small diameters are disadvantageous in this context. These can be more difficult to demould.

Coatings are another possibility. Choose a suitable coating for the shafts instead of a plain bearing. These coatings can be applied in thicknesses from just a few µm to several hundred µm (You can find out more about our tribo-coatings here).

Coatings are another possibility. Choose a suitable coating for the shafts instead of a plain bearing. These coatings can be applied in thicknesses from just a few µm to several hundred µm (You can find out more about our tribo-coatings here).

Coating powder and coated components made of metal (source: igus GmbH)

Thick-walled plain bearing dimensions – More is not always better

Thicker walls not always offer advantages related to the load-bearing and wear behaviour of plain bearings. They can even be disadvantageous, especially in the case of plain bearings made of polymer compounds. Nevertheless, polymer plain bearings with thick walls are often light weight, and also enable user to save money due to the utilization of cost-effective material and manufacturing method compared to steel or bronze.
Bearing walls that are too think involve further risks if injection moulding method is used in the process of making bearings. Thick component parts are tend to “sink in” after the injection process – small or larger indentations in the surface of the component. These can be avoided by placing recesses cleverly or supporting frame-like constructions.

If the injection moulding process comes up against its limits, other manufacturing methods can be used to produce solutions made of polymer. Wound bearings made of a filament fabric are flexible and comparatively cost-effective manufacturing method. 

                 

 

 “Roving”-wound plain bearings made of filament fabric (source: igus GmbH)

Long plain bearings – Trying for multiple-part solutions

Plain bearings with a geometry that is especially long, in relation to the diameter, and is tube-shaped can also be complicated. Long plain bearings with exact tolerances are difficult to produce. Concentricity and accuracy are often extremely important for these bearings. In such a case, it is better to choose multiple-part designs if possible. Additionally, it is not always necessary to fill the entire installation space between shafts and housing hole with plain bearings. It is often enough to fit out the ends with a plain bearing.

Find cost advantages and avoid cost pitfalls: we will be happy to advise you

However, these were some possibilities of improvement and potential pitfalls that can save or cost you more. Therefore, we are happy to help you to design your bearings, and work with you to find the best and most cost-effective solution – either with “off-the shelf” plain bearing dimensions or individual solutions according to your request.

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