iglidur® L250 - Material data

Maximum surface speed

m/s	Rotary	oscillating	Linear
Constant	1	0,7	2
Short-term	1,5	1,1	3

Table 02: Maximum surface speeds

Permitted surface speeds

iglidur® L250 has been developed especially for high surface speeds with low loads. Besides the physical limit, which is preset by the heating of the bearing, the coefficients of wear also act limitedly if rapidly high glide paths emerge at high peripheral speeds and the permitted wear limit is thus reached earlier. The maximum speeds can be gathered from Table 02.

iglidur® L250	Operating temperature
Lower	- 40 °C
Upper, long-term	+ 90 °C
Upper, short-term	+ 180 °C
Secure axially in addition	+ 55 °C

Table 03: Temperature limits for iglidur® L250

Temperatures

The iglidur® L250 bearings can be used in temperatures up to 180° C for the short-term. Note that a mechanical securing of the bearing is recommended from temperatures of 55° C. Higher temperatures can also cause the bearing to lose its press-fit seating and move in the bore.

Figure 04: Coefficients of friction dependent on the surface speed, p = 0,75 MPa

X = Surface speed [m/s]
Y = Coefficient of friction μ

Friction and wear

In the best pairing (with V2A shafts), friction coefficients of 0.14 are already reached with low loads. Coefficients of friction under 0.1 was already measured at 10 MPa. (Fig. 04 and 05).

iglidur® L250	Dry	Grease	Oil	Water
Coefficients of friction µ	0,08 - 0,19	0,09	0,04	0,04

Table 04: Coefficients of friction for iglidur® L250 against steel
(Ra = 1 µm, 50 HRC)

Figure 06: Wear, rotating application with different shaft materials, p = 1 MPa, v = 0,3 m/s
 
X = Shaft material
Y = Wear [μm/km]
 
A = Aluminum, hard-anodized
B = machining steel
C = Cf53
D = Cf53, hard chrome-plated
E = St37
F = V2A
G = X90

Shaft materials

As seen in Figure 06, many shafts are recommendable for low loads and low rotations.
 
The good coefficients of friction are additionally retained over a wide range of recommendable surface finishes for shafts. For loads greater than 1 MPa, particular attention should be paid to the shaft material used.

Medium	Resistance
Alcohols	+ to 0
Hydrocarbons	+
Fats, oils, without additives	+
Fuels	+
Diluted acids	0 to -
Strong acids	-
Diluted bases	+
Strong bases	0

+ resistant      0 partially resistant      - non-resistant
All specifications at room temperature [+20℃]
Table 05: Chemical resistance of iglidur® L250

Electrical properties

Specific forward resistance	> 1010 Ωcm
Surface resistance	> 1011 Ω

Chemical resistance

iglidur® L250 bearings are resistant to diluted alkalis and very weak acids as well as to solvents and all kinds of lubricants.
 

Radioactive rays

iglidur® L250 bearings are radiation resistant up to a radioactive intensity of 3 x 10⁴ Gy. Higher radiation affects the material and may potentially lead to a notable lowering of value of an important mechanical property.

UV-resistant

iglidur® L250 plain bearings change colour under the influence of UV rays. However, their properties do not deteriorate.
 

Vacuum

In application in vacuum, the potentially existent humidity is degassed. For this reason only the dry iglidur® L250 bearings are suitable for vacuum.

Electrical properties

The bearings are electrically insulating.

Maximum moisture absorption
by +23 °C/50 % r. F.	0,7 Wt.-%
Max. water absorption	3,9 Wt.-%

Table 06: Moisture absorption

Diagram 10: Effect of moisture absorption
 
X = Moisture absorption [weight %]
Y = Reduction of inside diameter [%]

humidity absorption / moisture absorption

Please take into account the humidity absorption in applications in which very minor bearing clearances occur.

Diameter d1 [mm]	Shaft h9 [mm]	iglidur® L250 E10 [mm]	Housing H7 [mm]
Up 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 iaw. ISO 3547-1 after press-fitting.

Installation tolerances

iglidur® L250 plain bearings are standard bearings for shafts with h-tolerance (recommended minimum h9). After the installation in a housing with nominal diameter, the inner diameter of the bearing automatically adjusts to the E10 tolerance. In certain dimensions the tolerance in dependence on the wall thickness deviates from this (See delivery program )