Industrial shaft seals

gab.ru Берг АБ bergab@ya.ru Тел. (495)-228-06-21,
Industrial
факс
shaft seals
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Surface roughness
The surface roughness to ISO 4288 (DIN
4768) of the counterface for radial shaft seals
should be kept within the following limits:
R a 0,2 to 0,8 µm
R z 1 to 4 µm
R max 6,3 µm
The lower values for R a and R z are minimum
values as otherwise lubricant supply to the
sealing lip will be affected. The temperature
rise caused by inadequate lubrication,
particularly at high circumferential speeds,
would lead to hardening and cracking of the lip
and thus to premature seal failure. If the
surfaces are too rough there will be excessive
seal lip wear and seal life will be shortened. If
the value R max is exceeded leakage may occur.
Surface finish
It is also important that the machining
operation does not leave any directionality
behind on the counterface, as this could lead
to leakage by pumping action, depending on
the direction of rotation. A suitable surface can
Table 12. Counterface tolerances for large diameter radial shaft seals, metric sizes
Shaft diameter Diameter tolerance (h11) Circularity tolerance (IT8)
Nominal Deviation Deviation
d 1
over incl. high low max
mm µm µm
180 250 0 –290 72
250 315 0 –320 81
315 400 0 –360 89
400 500 0 –400 97
500 630 0 –440 110
630 800 0 –500 125
800 1 000 0 –560 140
1 000 1 250 0 –660 165
1 250 1 600 0 –780 195
1 600 2 000 0 –920 230
2 000 2 500 0 –1 100 280
2 500 3 150 0 –1 350 330
3 150 4 000 0 –1 650 410
gab.ru Берг АБ bergab@ya.ru Тел. (495)-228-06-21, факс (495) 77 22