Skill and care in mounting are prerequisites for long bearing service life. In addition, cleanliness, and understanding the causes of premature bearing failure can help too.
Check that the counter surface (shaft seat) and other components such as the housing are clean, deburred and that they do not contain any abrasive particles. Check also the shaft for sharp edges, burrs or surface defects, which could damage the sliding surface of the bushings. Once all the components have been cleaned and checked, the bushing is ready to be installed.
To install bushings, with or without a flange, SKF recommends using a mounting dolly particularly for composite (fig. 1) and filament wound (fig. 2) bushings. To do this, place an O-ring on the dolly to keep the bushing in position. Then drive the bushing into place with a mechanical or hydraulic press or by tapping the dolly lightly with a hammer. To facilitate the mounting of small bushings, apply a light coating of oil or grease to the housing bore.
For larger bushings, SKF recommends using a mounting ring (fig. 3) because it aligns and centres the bushing while it is being pressed into place. When mounting larger bushings, use a solid lubricant paste, such as the SKF anti-fretting agent LGAF 3E, on the seating to reduce the risk of fretting corrosion and also to reduce the force required for mounting. SKF also recommends, particularly for larger bushings where more force is required that they be cooled before mounting.
Care should always be taken when mounting FW bushings not to damage the sliding layer or side faces.
To facilitate mounting FW busings, the bushing may be split lengthwise into two halves by using a diamond coated grinding wheel. Sufficient cooling fluid should be applied as well to avoid excessive temperatures, as they can destroy the bushing.
Composite and wrapped bronze bushings that are to be heavily loaded in operation should be mounted so that the butt joint is at 90° to the loaded zone during operation (fig. 4), otherwise service life will be reduced.
The position of the lubrication groove of solid bronze bushings depends on whether it is an oscillating or rotating or movement and, for the latter, whether oil or grease lubrication is applied (fig. 5).
When mounting, thrust washers should be positioned so that the steel backing abuts the housing wall.
If composite plain bearings, for example strips, are to be located in a housing using an adhesive, the adhesive should be suitable for the expected operating temperature and should have suitable expansion, aging resistance, strength and curing properties. If no operational experience is available, SKF recommends contacting an adhesive manufacturer for advice. When applying an adhesive, care should be taken so that no adhesive reaches the sliding surface.
SKF sintered bronze bushings are impregnated with a lubricant and. therefore, should be kept in it’s original package until just prior to mounting. Otherwise when the bushing comes in contact with absorbent material it may wick the oil away very quickly.
SKF logo