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iglidur® UW - Material data

Materials table

Genera l features Unit iglidur® UW test method
Density g/cm³ 1,52
Colour black
Max. humidity absorption at 23°C/50% R. H. % weight 0,2 DIN 53495
Max. water absorption3) % weight 0,8
Coefficient of surface friction, dynamic, against steel μ 0,15–0,35
pv value, max. (dry) MPa x m/s 0,11

Mechanical properties
Bending E-module MPa 9.600 DIN 53457
Tensile 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 properties
Max. long term application temperature °C +90
Max. short term application temperature °C +110
Minimum application temperature °C -50
thermal / heat 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)
Specific forward resistance Ωcm < 105 DIN IEC 93
surface resistance Ω < 105 DIN 53482
2) The good conductivity of this plastic can under certain conditions promote corrosion on a metallic contact body.
3) With regard to the application of the material in direct contact with water, it should be noted that all results have been obtained under laboratory conditions with DI water (de-ionized water). Hence we recommend application-specific tests under real application conditions.




Figure 01: Permitted PV values for iglidur® UW 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 in which the maximum temperatures clearly lie below +100° C. For application temperatures above this limit, the bearings made of iglidur® UW500 are available. Though iglidur® UW was developed for application in liquids, it is also suitable for dry operation. This one is particularly important in applications that call for both dry and wet operations. These applications can be seen often in practice. The features of the bearings made of iglidur® UW described in this section apply to the dry operation. Unless it is expressly mentioned otherwise.

Figure 02: Maximum recommended surface pressure dependent on the temperature (50 MPa to +20 °C)

X = Temperature [°C]
Y = Load [MPa]

 

Figure 03: Deformation under load and temperatures

X = Load [MPa]
Y = Deformation [m/s]

 
Mechanical properties

Maximum recommended surface pressure represents a mechanical material parameter. Tribological conclusions cannot be drawn from it. The pressure resistance of iglidur® UW bearings declines with increasing temperatures. Fig. 02 clarifies this connection.

Figure 03 shows the elastic deformation of iglidur® UW with radial loads. Under the maximum recommended surface pressure of 40 MPa, the deformation amounts to less than 1%.

m/s Rotary oscillating Linear
Constant 0,5 0,4 2
Short-term 1,5 1,1 3
Table 02: Maximum surface speeds

Permitted surface speeds

iglidur® UW is excellent for use in both dry and wet operations as well as with high speed. Through a hydrodynamic lubrication, attained under water with high speeds, surface speeds far above 2 m/s can be achieved.

In dry operation the iglidur® UW bearings can be used on the short term for up to 1.5 m/s.

iglidur® UW Operating temperature
Lower - 50 °C
Upper, long-term + 90 °C
Upper, short-term + 110 °C
Secure axially in addition + 80 °C
Table 03: Temperature limits for iglidur® UW

Temperatures

As already mentioned, iglidur® UW bearings are required for applications at low temperatures. In underwater operation, the medium usually conducts heat, meaning that the liquid temperature is of particular importance here. An additional securing is recommended at temperatures higher than +80°C.

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

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

 

Figure 05: Coefficients of friction dependent on the load, v = 0,01 m/s

X = Load [MPa]
Y = Coefficient of friction μ

 
Friction and wear

The surface finishes of the shafts should not be extremely smooth in order to prevent a high adhesion effect and the entailing increases in the coefficient of friction. Please contact us for the specifications of shaft surface finishes in underwater applications.

iglidur® UW Dry Grease Oil Water
Coefficients of friction µ 0,15 - 0,35 0,09 0,04 0,04

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

Wear, rotating application with various

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

Figures 06 and 07 show an excerpt of the results of tests with different shaft materials conducted with bearings made of iglidur® UW. For low loads with rotation, the combinations with the stainless steels X90 and V2A achieve the best wear values. The conditions shift with increasing loads. Please note that the wear increases vastly at loads > 5 MPa.

Wear in oscillating and rotating

Fig. 07: Wear with oscillating and rotating applications with Cf53 as a function of the load
 
Y = wear [μm/km]
 
A= Cf53
B= hard chrome-plated
C= V2A
D= St37
 
pink= oscillating
blue= rotating

 
 

Medium Resistance
Alcohols +
Hydrocarbons +
Greases, oils without additives +
Fuels +
Diluted acids 0 to -
Strong acids -
Diluted bases +
Strong bases + to 0
+ resistant      0 limited resistance      - not resistant
All specifications at room temperature[+20 °C]
Table 05: Chemical resistance of the iglidur® bearings UW


Electrical properties

Specific forward resistance < 105 Ωcm
Surface resistance < 105 Ω

Chemical resistance

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

Radioactive rays

iglidur® UW bearings are radiation resistant up to a radiation intensity of 3 x 102 Gy.

UV-resistant

iglidur® UW bearings are resistant to the influence of UV rays.

Vacuum

The use in vacuum is possible only conditionally. Only dry bearings made of iglidur® UW should be tested in vacuum.

Electrical properties

Bearings made of iglidur® UW are electrically conductive.

Maximum moisture absorption
by +23 °C/50 % r. F. 0,2 weight-%
Max. water absorption 0,8 weight-%

Table 06: Moisture absorption of iglidur® UW

Effect of moisture absorption on plain bearings

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

 
humidity absorption / moisture absorption

The humidity absorption of iglidur® 200 bearings amounts to about 0,2% in standard climatic conditions. The saturation limit in water is 0,8 %. These values are so low that a moisture expansion need to be considered only in extreme cases.

Diameter
d1 [mm]
Shaft
h9 [mm]
iglidur® UW
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® UW bearings are standard bearings for shafts with h-tolerance (recommended minimum h9).
 
The bearings are designed for press-fit in a housing with h7 tolerance. 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 )