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iglidur® UW - Material data

Material table

General specification

Unit

iglidur® UW

Test method

density

g/cm³

1,52

Colour

black

max. Moisture absorption at 23°C/50% room humidity.

% by weight

0,2

DIN 53495

max. Water absorption3)

% by weight

0,8

Sliding friction coefficient, dynamic, against steel

μ

0,15-0,35

pv value, max. (dry)

MPa x m/s

0,11

Mechanical specification

flexural modulus

MPa

9.600

DIN 53457

flexural strength at 20°C

MPa

90

DIN 53452

Compressive strength

MPa

70

maximum recommended surface pressure (20°C)

MPa

40

Shore D hardness

78

DIN 53505

Physical and thermal specification

Upper long-term application temperature

°C

+90

upper short-term application temperature

°C

+110

Lower application temperature

°C

-50

thermal conductivity

W/m x K

0,60

ASTM C 177

coefficient of thermal expansion (at 23°C)

K-1 x 10-5

6

DIN 53752

Electrical properties2)

Volume resistivity

Ωcm

< 105

DIN IEC 93

surface resistance

Ω

< 105

DIN 53482

  1. The good conductivity of this plastic can, under certain circumstances, favour the formation of corrosion on the metallic contact body.
  2. With regard to the use of the material in direct contact with water, it must be pointed out that all results under deionised water (fully demineralised water) under laboratory conditions. We therefore recommend application-specific tests under real operating conditions.
    Table 01: Material data

diagram. 01: Permissible pv value for iglidur® UW plain bearings with 1 mm wall thickness in dry operation against a steel shaft, at +20 °C, installed in a steel housing

X = surface speed [m/s]
Y = load [MPa]

iglidur® UW was developed for underwater applications where the maximum temperatures are well below +100°C. For application temperatures above this limit, the plain bearings from iglidur® UW500 are available. Although iglidur® UW was developed for applications in liquids, it is also suitable for dry operation. This is particularly important for applications that run both dry and under liquids. These applications are often encountered in practice. When the specification of the bearing from iglidur® UW is described in this chapter, dry operation is meant. Unless explicitly stated otherwise.

diagram. 02: maximum recommended surface pressure as a function of temperature (50 MPa at +20 °C)

X = temperature [°C]
Y = load [MPa]

Mechanical specification
The maximum recommended surface pressure is a mechanical material parameter. Conclusions on the tribology cannot be drawn from this. The compressive strength of iglidur® UW bearings decreases with increasing temperatures. diagram. 02 illustrates this correlation.

Diagram 03: Deformation under pressure and temperature

X = load [MPa]
Y = Deformation [%]

diagram. 03 shows the elastic deformation of iglidur® UW under radial load. Under the maximum recommended surface pressure of 40 MPa, the deformation is less than 1 %.

m/s

rotating

oscillating

linear

continuous

0,5

0,4

2

short-term

1,5

1,1

3

Table 02: Maximum surface speed

Permissible sliding speeds
iglidur® UW can be used well in dry operation as well as under liquids and at higher speeds. hydrodynamic lubrication, as achieved in the underwater area at high speeds, can achieve sliding speeds of far more than 2 m/s.

In dry operation, iglidur® UW plain bearings can be used up to 1.5 m/s short-term.

iglidur® UW

Application temperature

lower

- 50 °C

upper, long-term

+ 90 °C

upper, short-term

+ 110 °C

additional axial protection from

+ 80 °C

Table 03: Temperature limits for iglidur® UW

Temperatures
As already mentioned, iglidur® UW bearings are required for use in the low temperature range. In underwater operation, the medium is usually heat-dissipating, so that the fluid temperature is particularly important here. An additional safety device is required for temperatures higher than +80 °C.

Diagram 04: Coefficient of friction as a function of the surface speed, p = 0.75MPa

X = surface speed [m/s]
Y = coefficient of friction μ

Friction and wear
The roughness of the shafts should not be too smooth in order to avoid a high adhesion effect and the associated increase in friction coefficient. For information on shaft roughness for underwater applications, please contact us.

Diagram 05: Coefficient of friction as a function of the pressure, v = 0.01m/s

X = load [MPa]
Y = coefficient of friction μ

iglidur® UW

dry

Grease

oil

water

coefficient of friction µ

0,15 - 0,35

0,09

0,04

0,04

Table 04: coefficient of friction for iglidur® UW against steel
(Ra = 1 µm, 50 HRC)

Wear, rotating applications with different

diagram. 06: Wear, rotating application with different shaft materials, p = 1 MPa, v = 0.3 m/s

X = Shaft material
Y = wear [μm/km]

A = aluminium, hard anodised
B = free cutting steel
C = Cf53
D = Cf53, hard chrome-plated
E = HR carbon steel
F = 304 SS
G = high grade steel

Shaft materials
Diagrams 06 and 07 show an extension of the results of tests carried out with different shaft materials using plain bearings from iglidur® UW. At low loads under rotation, the combinations with the stainless steels high grade steel and V2A achieve the best wear values. The ratios shift with increasing loads. Please note that wear increases significantly with loads > 5 MPa.

Shaft materials
Wear for oscillating and rotating

diagram. 07: Wear in oscillating and rotating applications with Cf53 as a function of the load

Y = wear [μm/km]

A= Cf53
B= hard chrome plated
C= 304 SS
D= HR carbon steel

pink= oscillating
blue= rotating

Medium

Resistance

Alcohols

hydrocarbons

Greases, oils, not additivated

fuels

Diluted acids

0 to -

strong acids

-

Dilute bases

strong bases

+ to 0

+ resistant 0 conditionally resistant - not resistant
All data at room temperature [+20 °C]
Table 05: chemical resistance of iglidur® UW

Chemical resistance
iglidur® UW plain bearings are resistant to diluted alkalis and very weak acids as well as to solvents and all types of lubricants.

**
Electrical specification

Volume resistivity

< 105 Ωcm

surface resistance

< 105 Ω

Radioactive radiation
Bearings made of iglidur® UW are radiation-resistant up to a radiation intensity of 3 x 102 Gy.

Maximum moisture absorption

at +23 °C/50 % room humidity.

0.2 % by weight

max. total moisture absorption

0.8 % by weight

Table 06: Moisture absorption of iglidur® UW

Moisture absorption
The moisture absorption of iglidur® UW bearings is about 0.2 % in a normal climate. The saturation limit in water is 0.8 %. These values are so low that consideration of swelling due to moisture absorption is only necessary in extreme cases.

Influence of moisture absorption

diagram. 10: Influence of moisture absorption

X = Moisture absorption [Gew.-%]
Y = Reduction inside ø [%]

Diameter****d1 [mm]

shaft h9**[mm]**

iglidur® UW****E10 [mm]

housing H7**[mm]**

to 3

0 - 0,025

+0,014 +0,054

0 +0,010

> 3 to 6

0 - 0,030

+0,020 +0,068

0 +0,012

> 6 to 10

0 - 0,036

+0,025 +0,083

0 +0,015

> 10 to 18

0 - 0,043

+0,032 +0,102

0 +0,018

> 18 to 30

0 - 0,052

+0,040 +0,124

0 +0,021

> 30 to 50

0 - 0,062

+0,050 +0,150

0 +0,025

> 50 to 80

0 - 0,074

+0,060 +0,180

0 +0,030

> 80 to 120

0 - 0,087

+0,072 +0,212

0 +0,035

> 120 to 180

0 - 0,100

+0,085 +0,245

0 +0,040

Table 07: Important tolerances according to ISO 3547-1 after press-fitting

Installation tolerances
iglidur® UW plain bearings are standard bearings for shafts with tolerance (recommended minimum h9).

The bearings are designed to be pressed into a h7-toleranced mounting. After installation in a mounting with nominal dimensions, the inner diameter of the bearing with E10 tolerance adjusts itself. For certain dimensions, the tolerance deviates depending on the wall thickness (see product range).

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