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About slide bearings

LOADING CAPACITY

The loading capacity of a bearing with an inside diameter of d mm, length 1 mm and load F Newton, is calculated as follows:

p = F N/mm2
d x l

With sliding speed < 1m/min, in intermittent operation, a surface pressure of half of the yield stress value of the material is permitted. With sliding speed > 1m/min, or continuous operation – the so-called PV value, Pressure Velocity, (N/mm²x m/sec) is used to determine maximum load capacity. For most bronze grades a PV value of 1.75 (N/mm²x m/sec) is permitted. An axial movement normally allows for a greater PV value.

BEARING CLEARANCE

For oil lubricated bearings a clearance of 1.5–2.5 ‰ of the inside diameter of the bearing is suggested. For grease lubricated bearings the clearance should be two times greater. For back-and-forth movement a clearance as small as possible is used (0.5– 1‰). In high temperatures the clearance should be bigger than normally.

LUBRICATION

The lubrication groove is very important in mounted bearings. Poor lubrication is often the fault of flawed lubrication grooves. In hydrodynamiclubrication the groove should not be situated in the load area. With radial reciprocating movement, place the grooves in the load area, the distance of the grooves should be <2 x angle of movement. Solid lubricants can be used in sliding speeds of under 0.5 m/sec

THINGS TO REMEMBER IN DESIGN:

  • the lubrication grooves are placed perpendicularly against the direction of movement
  • great sliding speed = viscous lubricant
  • slow sliding speed = rigid lubricant
  • viscosity is chosen according to running temperaturen

MATING MATERIAL

  • at least 95HB harder than bronze
  • for tin bronze alloys a mating material of minimum 300HB
  • for aluminum bronze alloys a mating material of a minimum 400HB
  • optimal mating material 500HB
  • recommended surface finish <1 Ra
  • for stainless steel martensitic grades. An austenitic sliding surface should be hard chromed.

FRICTION

The coefficient of friction for the bronze bearing:

  • in hydrodynamic lubrication ≈ 0,02–0,08
  • in the movement area ≈ 0,02–0,08
  • in a mixed friction area ≈ 0,08–0,15
  • solid lubrication ≈ 0,08–0,25 depending on the lubrican type

TECHNICAL SERVICES

Tel. 03 342 7700

STOCK AVAILABILITY

Some products and dimensions are held at stock. Check availability for each dimension from our sales. We can also produce customer specific dimensions and products.

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Johnson Metall AB
Stålgatan 15
SE-703 83 Orebro

Phone
+46 1917 5100

Information
info.orebro@johnson-metall.com


Johnson Metall AB

Stålgatan 15, SE-703 83 Orebro

 +46 1917 5100   sales.orebro@johnson-metall.com