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Bushing data

Solid bronze bushings
Dimension standardsNot standardized

Material
Multi-component bronze
CuSn7Zn4Pb7-B
(designation suffix M1)

Permissible operating temperature range-40 to +250 °C (-40 to +480 °F)

Permissible load
Dynamic: 25 N/mm2
Static: 45 N/mm2

Permissible sliding velocity0,5 m/s (1.6 ft/s)

Coefficient of friction µ
0,08 to 0,15 (greased)


Sintered bronze bushings
Dimension standardsNot standardized

Tolerances
Straight bushings (fig. 1)
Flanged bushings (fig. 2)

Material
Sintered metallic bronze and graphite matrix (approximately 1% weight of graphite) with fully impregnated porosity;
material composition is SINT A51 with a porosity volume of approximately 28%, impregnated with mineral oil

Permissible operating temperature range-10 to +90 °C (+15 to +195 °F)

Permissible load
Dynamic: 10 N/mm2
Static: 20 N/mm2

Permissible sliding velocity0,25 to 5,0 m/s (0.8 to 16.4 ft/s)

Coefficient of friction µ
0,05 to 0,10 (greased)


Wrapped bronze bushings
Dimension standardsISO 3547-1:2006

Tolerances
ISO 3547-1:2006
Checking values: ISO 3547-2:2006

Material
CuSn8 (entirely bronze)

Permissible operating temperature range-40 to +150 °C (-40 to +300 °F)

Permissible load
Dynamic: 40 N/mm2
Static: 120 N/mm2

Permissible sliding velocity1,0 m/s (3.2 ft/s)

Coefficient of friction µ
0,08 to 0,15 (greased)


PTFE composite bushings
Dimension standardsMetric straight bushings: ISO 3547-1:2006
(with a few exceptions)

Inch straight and metric flanged bushings: not standardized

Tolerances

Metric straight bushings, outside diameter D: ISO 3547-1:2006
Checking values: ISO 3547-2:2006

Flanged bushings (mounted):

  • Flange diameter D1: ±0,5 mm
  • Width flange B1: +0,05/-0,20 mm
Chamfer dimensions (Product table)

Materials
For additional information (Design and variants)

Steel backing with a layer of sintered tin/bronze, pores filled and covered with a running-in layer of PTFE with molybdenum disulphide additives

Operating clearance1)

Guideline values depending on selected shaft and housing tolerances:

Excessive clearance may have a negative influence on the service life of PTFE composite bushings if they are not lubricated.

Permissible operating temperature range-200 to +250 °C (-330 to +480 °F)

Permissible load
Dynamic: 80 N/mm2
Static: 250 N/mm2

Permissible sliding velocity2,0 m/s (6.5 ft/s)

Coefficient of friction µ
0,03 to 0,25

Chemical properties
Steel backing and sintered tin/bronze layer are the primary factors in determining the chemical resistance of SKF composite plain bearings, as the sliding (covering) layers are resistant to most chemicals. The covering layer is virtually inert because of its PTFE content, although at increasing temperatures molten alkali metals and free fluorine attack it.
At room temperature the sintered tin/bronze structure has good resistance to sea water, steam, atmospheric influences, salt solutions and sulphuric acid, but not to oxidizing acids or media containing ammonia.
All exposed surfaces of the steel backing are electrolytically tin-plated but this provides only limited protection against corrosion in most applications. In cases where the bushings are to be exposed to corrosive media, or where there is a risk of corrosion in the contact between the steel backing and the housing material, the backing can be protected by a nickel, chromium or zinc coating applied electrolytically.
For additional information, contact the SKF application engineering service.


1)The values quoted for operating clearance are valid at room temperature. If the operating temperature is higher, it is expected that for every 20 °C temperature increase the operating clearance decreases by 0,0016 mm for PTFE composite bushings.
The actual operating clearance can be increased or decreased within the recommended limits by matching shaft and housing bores having appropriate diameter values within the specified limits. If in certain applications smooth running is required, or if the bearing is only lightly loaded, SKF recommends selecting the tolerances so that maximum values for operating clearance are applied.

POM composite bushings
Dimension standardsISO 3547-1:2006
(with a few exceptions)

Tolerances

Outside diameter D: ISO 3547-1:2006
Checking values: ISO 3547-2:2006

Chamfer dimensions (Product table)

Materials
For additional information (Design and variants)

Steel backing with a layer of sintered tin/bronze, pores filled and covered with a layer of POM composite

Operating clearance1)

Guideline values depending on selected shaft and housing tolerances:

Excessive clearance may have a negative influence on the service life of PTFE composite bushings if they are not lubricated.

Permissible operating temperature range-40 to +110 °C (-40 to +230 °F), +130 °C (+265 °F) for short periods

Permissible load
Dynamic: 120 N/mm2
Static: 250 N/mm2

Permissible sliding velocity2,5 m/s (8.2 ft/s)

Coefficient of friction µ
0,02 to 0,20

Chemical properties
Steel backing and sintered tin/bronze layer are the primary factors in determining the chemical resistance of SKF composite plain bearings, as the sliding (covering) layers are resistant to most chemicals. The acetal resin-covering layer is largely resistant to organic substances.
At room temperature the sintered tin/bronze structure has good resistance to sea water, steam, atmospheric influences, salt solutions and sulphuric acid, but not to oxidizing acids or media containing ammonia.
All exposed surfaces of the steel backing are electrolytically tin-plated but this provides only limited protection against corrosion in most applications. In cases where the bushings are to be exposed to corrosive media, or where there is a risk of corrosion in the contact between the steel backing and the housing material, the backing can be protected by a nickel, chromium or zinc coating applied electrolytically.
For additional information, contact the SKF application engineering service.

Electrical propertiesThe acetal resin-covering layer may act as electrical insulators when new. To avoid the build-up of static electricity, components at risk should be grounded.
For additional information, contact the SKF application engineering service.



1)The values quoted for operating clearance are valid at room temperature. If the operating temperature is higher, it is expected that for every 20 °C temperature increase the operating clearance decreases by 0,005 mm for POM composite bushings.
The actual operating clearance can be increased or decreased within the recommended limits by matching shaft and housing bores having appropriate diameter values within the specified limits. If in certain applications smooth running is required, or if the bearing is only lightly loaded, SKF recommends selecting the tolerances so that maximum values for operating clearance are applied.

PTFE polyamide bushings
Dimension standardsISO 3547-1:2006

Tolerances
ISO 3547-1:2006
Checking values: ISO 3547-2:2006

Material
Glass-fibre reinforced thermoplastic containing PTFE

Permissible operating temperature range-30 to +110 °C (-20 to +230 °F)

Permissible load
Dynamic: 40 N/mm2
Static: 80 N/mm2

Permissible sliding velocity1,0 m/s (3.2 ft/s)

Coefficient of friction µ
0,06 to 0,15


Filament wound bushings
Dimension standardsISO 4379:1993

Tolerances

Bore diameter d:

  • C10 (unmounted)
  • D11 (mounted in a housing with tolerance class H7)

Outside diameter D: s8

Width: h13


Materials
For additional information (Design and variants)

Backing: high strength glass fibre
Sliding surface: high strength polyester and PTFE
Both layers are wound and embedded in an epoxy resin matrix.

Operating clearance
Guideline values depending on selected shaft and housing tolerances (table 5);
increasing clearance, for example as a result of wear, is minimal during the service life of these bushings

Permissible operating temperature range-50 to +140 °C (-60 to +285 °F)

Permissible load
Dynamic: 140 N/mm2
Static: 200 N/mm2

Permissible sliding velocity0,5 m/s (1.6 ft/s)

Coefficient of friction µ
0,03 to 0,08

Thermal expansion
13 x 10-6 K-1 (similar to steel)

Thermal conductivity
0,4 W/mK

Density
1,87 g/cm3

Chemical properties
Excellent resistance to corrosive media, including salt water and many chemicals (table 6)

Electrical propertiesGood insulator, which prevents passing of electric current


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