iglidur® L250 - Material data

Material table

General specification

Unit

iglidur® L250

Test method

density

g/cm³

1,50

Colour

beige

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

% by weight

0,7

DIN 53495

max. total moisture absorption

wt.-%

3,9

Sliding friction coefficient, dynamic, against steel

0,08-0,19

pv value, max. (dry)

MPa x m/s

0,4

Mechanical specification

flexural modulus

MPa

1.950

DIN 53457

flexural strength at 20°C

MPa

DIN 53452

Compressive strength

MPa

maximum recommended surface pressure (20°C)

MPa

Shore D hardness

DIN 53505

Physical and thermal specification

Upper long-term application temperature

°C

+90

upper short-term application temperature

°C

+180

Upper short-term ambient temperature1)

°C

+200

Lower application temperature

°C

-40

thermal conductivity

W/m x K

0,24

ASTM C 177

coefficient of thermal expansion (at 23°C)

K-1 x 10-5

DIN 53482

Electrical specification

Volume resistivity

Ωcm

> 1010

DIN IEC 93

surface resistance

> 1011

DIN 53482

Without additional load; no sliding movement; relaxation not excluded

Table 01: Material data

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iglidur® L250 is a plain bearing material for high speed, fast sliding movements and low coefficient of friction. The material iglidur® L250 can utilise these advantages particularly at low loads. Applications in which these advantages play a role include fans, small motors, high-speed sensors and magnet technology.

surface pressure as a function of temperature

Mechanical specification
The maximum recommended surface pressure represents a mechanical material parameter. Conclusions on the tribology cannot be drawn from this. The compressive strength of iglidur® L250 plain bearings decreases with increasing temperatures. diagram. 02 illustrates this correlation.

diagram. 03 shows the elastic deformation of iglidur® L250 under radial load. Under the maximum recommended surface pressure of 45 MPa, the deformation is less than 3%. Plastic deformation can be neglected up to this value. However, it also depends on the duration of the impact.

load, surface pressure

Maximum surface speed

m/s

rotating

oscillating

linear

continuous

0,7

short-term

1,5

1,1

Table 02: Maximum surface speed

Permissible sliding speeds
iglidur® L250 has been developed precisely for high sliding speeds at low loads. In addition to the physical limit, which is specified by the bearing heating, the wear values also have a limiting effect if high sliding distances quickly occur at high circumferential speeds and the permissible wear limit is thus reached earlier. The maximum speeds can be found in Table 02.

iglidur® L250

Application temperature

below

- 40 °C

upper, long-term

+ 90 °C

upper, short-term

+ 180 °C

additional axial protection from

+ 55 °C

Table 03: Temperature limits for iglidur® L250

Temperatures
iglidur® L250 bearings can be used at temperatures of up to 180°C. It should be noted that mechanical securing of the bearing is recommended from temperatures of 55°C. Higher temperatures can cause the bearings to lose their press fit and move in the hole.

friction and wear
In the best pairing (against 304 SS shafts), a low load coefficient of friction of 0.14 is achieved. Even at 10 MPa coefficients of friction below 0.1 were measured (diagram. 04 and 05).

diagram. 05: coefficient of friction as a function of the load

diagram. 06: Wear, rotating application with different

Shaft materials
As can be seen in diagram 06, a large number of shafts are recommended for low load and low rotation.

The good coefficients of friction are also maintained over a wide range of recommended shaft roughnesses. For loads greater than 1 MPa, special attention should be paid to the shaft material used.

Shaft materials

diagram. 07: Wear in rotating and oscillating applications with shaft material

Medium

Resistance

Alcohols

+ to 0

Hydrocarbons

Greases, oils, not additivated

fuels

Diluted acids

0 to -

strong acids

Dilute bases

strong bases

+ resistant 0 conditionally resistant - not resistant
All data at room temperature [+20 °C]
Table 05: chemical resistance of iglidur® L250

Chemical resistance
iglidur® L250 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

> 1010 Ωcm

surface resistance

> 1011 Ω

Radioactive radiation
Bearings made from iglidur® L250 are resistant to radiation up to a radiation intensity of 3 x 104 Gy. Higher radiation attacks the material and may lead to a noticeable reduction in the value of an important mechanical specification.

Maximum moisture absorption

at +23 °C/50 % room humidity.

0.7 % by weight

max. total moisture absorption

3.9 % by weight

Table 06: Moisture absorption

Moisture absorption
Please consider the moisture absorption in applications where the smallest bearing clearance is important.

Diameter****d1 [mm]

shaft h9**[mm]**

iglidur® L250****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® L250 plain bearings are standard bearings for shafts with h-tolerance (recommended minimum h9). After installation in a mounting with nominal dimensions, the inner diameter of the bearing with E10 tolerance is set automatically. For certain dimensions, the tolerance deviates from this depending on the wall thickness (see product range).