SKF - Industrial Shaft Seals

Radial shaft seals
Friction
To be effective, the lip of a radial shaft seal must
always exert a certain radial load on the counter
face. The friction resulting from this radial
load is only part of the total contact friction and
power loss at the sealing position. Other contrib
uting factors include:
• type of medium being sealed
• pressure differential across the seal
• circumferential speed
• ambient temperature
• lubricant and lubrication method
• condition of the counterface
Diagram 6 provides an indication of the friction
losses that may be expected when a radial
shaft seal with a conventional sealing lip is properly
installed and fully lubricated.
The running-in phase of the sealing lip lasts
a few hours. During this time, the friction losses
are somewhat higher than during normal
operation.
Seals intended for applications with high
pressure differentials typically have greater
losses than specified in the diagram. SKF Wave
seals, on the other hand, typically have losses
lower than those indicated in the diagram.
Diagram 6
Friction losses of radial shaft seals as a function of rotational speed and shaft diameter
Friction loss [W]
600
Rotational speed [r/min]
5 000 4 000 3 000
500
400
2 000
300
200
1 000
100
500
0
10 20
(0.394) (0.787)
40
(1.575)
60
(2.362)
80
(3.150)
100
(3.937)
120
(4.724)
140
(5.512)
Shaft diameter [mm (in.)]
66