iglidur® M250 - Material data

The most important specifications at a glance

Particularly resistant to edge pressure
Particularly resistant to shocks and impacts
Particularly resistant to dirt and dust
Fogging behaviour according to DIN 75201-B

When do I use this material?

If the bearing is exposed to heavy soiling
are exposed
For excellent vibration dampening
At low to medium speeds
When mechanical reworking is required
Insensitive to edge pressure
High impact resistance
Thick wall thicknesses according to DIN 1850

When do I use a different material?

For applications in wet areasiglidur®
H, sleeve bearing, mm
When very high precision is required
iglidur® P, sleeve bearing, mm
For very smooth shafts
iglidur® J, sleeve bearing, mm
When a cost-effective bearing with the highest
wear resistance is required
iglidur® R, sleeve bearing, mm

Permissible sliding speeds

As standard, iglidur® M250 is manufactured as a thick-walled bearing. iglidur® M250 is best suited for low to medium surface speeds. The maximum permissible surface speed in dry operation is 0.8 m/s (rotating) or 2.5 m/s (linear). In practice, these limit values cannot always be achieved due to the interaction of various influences.

Maximum surface speed

m/s	Rotating	Oscillating	linear
permanent	0.8	0.6	2.5
Short-term	2	1.4	5

Surface Speedp x v value and lubrication

Friction and wear

The coefficient of friction μ of a plain bearing is influenced by surface speed and load, among other factors.

coefficient of friction for iglidur® M250 against steel (Ra = 1 μm, 50 HRC):

iglidur® M250	dry	Greases	Oil	Water
Coefficients of friction µ	0.18-0.40	0.09	0.04	0.04

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

Further information

Coefficient of frictionWear resistance

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

iglidur® M250

Shaft materials

Friction and wear are also highly dependent on the mating partner. If the coefficient of friction is considered, the most favourable surface finish of the shaft for iglidur® M250-bearing is Ra = 0.6 mm. diagram. 06 and 07 show an extension of the results of tests with different shaft materials that were carried out with iglidur® M250 plain bearings. Up to a load of 2 MPa, the shaft material plays a comparatively minor role in rotation. A suitable shaft material should therefore be used for higher loads. These are hardened shafts, such as Cf53 or hard chrome-plated shafts. Diagram 07 shows that iglidur® M250 is much better suited for rotary movements than for swivelling movements. However, it must be mentioned that in practice the vibrations acting on the bearing are often particularly high during swivelling movements. This is where iglidur® M250 can utilise its special damping specification. Such vibrations are excluded in our test, so the comparison between rotation and swivelling operation is initially surprising.
Shaft materials

Wear in pivoting and rotating applications

Chemical resistance

iglidur® M250 plain bearings have good resistance to chemicals. They are resistant to most lubricants. Most weak organic and inorganic acids do not attack iglidur® M250.

+ resistant 0 conditionally resistant - not resistant
All data at room temperature [+20 °C]

Medium	Resistance
Alcohols	+ up to 0
Hydrocarbons	+
Greases, oils without additives	+
Fuels	+
Diluted acids	0 to -
Strong acids	-
Diluted alkalines	+
Strong alkalines	0

Radioactive radiation

Bearings made from iglidur® M250 can be used to a limited extent under radioactive radiation. They are resistant up to a radiation intensity of 1 -104 Gy.

UV resistance

iglidur® M250 plain bearings are permanently resistant to UV radiation.

Vacuum

In a vacuum, iglidur® M250 plain bearings outgas. The relatively high moisture absorption of the bearing therefore limits its use in a vacuum.

chemical resistance

iglidur® M250 plain bearings are electrically insulating

Resistance	Value
Specific transitional resistance	> 10¹³ Ωcm
Surface resistance	> 10¹¹ Ω

Installation tolerances

iglidur® M250 bearings require relatively large bearing clearances for optimum operation. These ensure that the bearing bushes work reliably even with temperature expansion and water absorption. The disadvantages of the bearing clearance are compensated for by the vibration-damping properties and the bearings are designed to be pressed into an H7-tolerated mounting. After installation in a mounting with a nominal dimension, the inner diameter of the bearings is automatically adjusted with D11 tolerance. The shaft should be at least H9-toleranced.

Diameter d1 [mm]	Shaft h9 [mm]	iglidur® M250 D11 [mm]	Housing H7 [mm]
up to 3	0 - 0.025	+0.020 +0.080	0 +0.010
> 3 up to 6	0 - 0.030	+0.030 +0.105	0 +0.012
> 6 up to 10	0 - 0.036	+0.040 +0.130	0 +0.015
> 10 up to 18	0 - 0.043	+0.050 +0.160	0 +0.018
> 18 up to 30	0 - 0.052	+0.065 +0.195	0 +0.021
> 30 up to 50	0 - 0.062	+0.080 +0.240	0 +0.025
>50 to 80	0 - 0.074	+0.100 +0.290	0 +0.030