Slide bearings

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.

Designing slide bearings:

Stress rate

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

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:

• The lubrication grooves are placed directly against the direction of movement.
• The grooves are placed in the axle if the bearing spins.
• High sliding speed = fluent lubricant
• Low sliding speed = stiff lubricant
• The viscosity is chosen according to the running temperature.

Technical service

Our technical service staff will help you in selecting the right material and type of bearing.

Bearing clearance

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.

Material of the counter surface

• at least 100 HB harder than bronze
• min. of 300 HB counter surface for tin bronze
• min. of 400 HB counter surface for aluminum bronze
• optimal counter surface: 500 HB
• recommended surface smoothness: < 1 Ra
• stainless steel for martensite qualities; austenitic sliding surfaces should be hard chrome plated

Friction

Friction coefficient of bronze bearings:

• hydrodynamic lubrication = 0.001-0.02
• in area of variation = 0.02-0.08
• in area of mixed friction = 0.08-0.15
• solid lubricant = 0.08-0.25

Our selection comprises seven different types of slide bearings intended for demanding purposes:

• Cast bronze bearings for grease and oil lubrication. More than 200 standard sizes straight from stock (max. Ds 210). Custom measurements upon order.
• Sintered, self-lubricating slide bearings. More than 250 standard sizes straight from stock (max. Ds 100 mm).
• Self-lubricating, Drymet multi-layered bearings. More than 100 standard sizes straight from stock (radial bearings: max. Ds 160 mm, axial bearings: max. Ds 65 mm).
• Self-lubricating, Frimet multi-layered bearings - straight and flanged. More than 250 standard sizes straight from stock (straight: max. DS 300, flanged: max. DS 45)
• Straight and flanged, rolled bronze bearings with grease pockets - especially suitable for to-and-fro movements
• Bimet multi-layered bearings for grease lubrication. More than 75 standard sizes straight from stock. (max. Ds 75 mm).
• Self-lubricating Oiles 500 bronze bearings with solid lubricant. Choice of frame material and lubricant according to use (max. stress 90 N/mm2).