Slide bearings are especially suitable for large loads and sliding speeds. Thanks to their geometrical shape and lubricant film, they withstand impact-type force, suppress vibration and are quiet. The bearings come in any shape and size to facilitate installation and maintenance. With the correct lubrication, slide bearings almost non-wearing.
The stress rate (p) for a bearing that has an inner diameter of d mm, length 1 mm and a load of F Newtons is calculated as follows:
p = F / (d x 1) N / mm2
Sliding speed < 1 m/min and occasional use: a surface pressure of half the material's yield value can be permitted.
Sliding speed > 1 m/min or continuous use: a so-called PV value (N/mm2 x m/sec) is used to determine the maximum rate of stress. A PV value of 1.75 N/mm x m/sec can be permitted for several types of bronze. An axial motion usually permits a greater PV value.
If the sliding speed is more than 60 m/min, hydrodynamic lubrication is usually necessary.
Lubrication grooves have important implications for bearings. Insufficient lubrication is often the consequence of defective lubrication grooves. With hydrodynamic lubrication, the grooves should not be placed in the area of stress. In a to-and-fro motion, the grooves are placed in the area of stress and the distance of the grooves is < 2 x the angle of motion. Solid lubricants may be used when the sliding speed is less than 0.5 m/sec.
Remember the following when designing:
Our technical service staff will help you in selecting the right material and type of bearing.
A clearance of 1.5-2.5 ‰ of the bearing's inner dimension is recommended for oil lubricated bearings. The clearance for grease lubricated bearings should be twice as much. The clearance for bearings moving in a to-and-fro motion should be the smallest possible (0.5-1 ‰). In high temperatures, the clearance should be larger than normal.
Friction coefficient of bronze bearings:
Our selection comprises seven different types of slide bearings intended for demanding purposes:
Johnson Metall AB
SE-703 83 Orebro
+46 1917 5100