Rotary Shaft Seal Engineering

 

Rotary Shaft Seal Tolerances 

DIN/RMA Standard

Bore Dia.
DIN 3760 (m/m)
RMA (m/m)
Metal O.D
Rubber O.D.
Metal O.D
Rubber O.D
up to 50
+0.10/+0.20
+0.15/+0.30
+0.08/+0.20
+0.15/+0.3
up to 80
0.13/0.23
0.20/0.35
0.09/0.23
0.20/0.35
up to 120
0.15/0.25
0.20/0.35
0.10/0.25
0.20/0.35
up to 180
0.18/0.28
0.25/0.45
0.12/0.28
0.25/0.45
up to 300
0.20/0.30
0.30/0.45
0.20/0.35
0.30/0.45
up to 400
0.23/0.35
0.30/0.55
0.20/0.45
0.30/0.55

 

 RMA STANDARD

Bore Dia.
Metal OD
Rubber OD
Normal Press Fit
Tolerance
Normal Press Fit
Tolerance
up to 2"
0.005+/-0.002
0.008+/-0.003
+0.003~0.007
+0.08~0.17mm
+0.005~0.011
+0.13~0.28mm
up to 3"
0.0055 +/- 0.0025
0.010+/-0.003
+0.003~0.008
+0.08~0.20mm
+0.007~0.013
+0.18~0.33mm
up to 5"
0.0065+/-0.003
0.0105+/-0.003
+0.0035~0.0095
+0.09~0.24mm
+0.0075~0.0135
+0.19~0.34mm
up to 7"
0.007+/-0.003
0.012+/-0.004
+0.004~0.010
+0.10~0.25mm
+0.008~0.016
+0.20~0.40mm
up to 12"
0.0085+/-0.0035
0.0125+/-0.004
+0.005~0.012
+0.13~0.30mm
+0.0085~0.0165
+0.22~0.42mm
up to 20"
0.012+/-0.005
0.015+/-0.005
+0.007~0.017
+0.18~0.43mm
+0.010~0.020
+0.26~0.50mm

 

 

The Design of Bore for Rotary Shaft Seals

Bore Diameter and Seal O.D. (DIN)

Bore Diameter (mm) Tolerance Range (H8) Metal Cased Seal O.D. (mm) Rubber Covered Seal O.D. (mm)

Up to 6

0 to +18 +0.10 to +0.20 +0.15 to +0.30

Up to 10

0 to +22
Up to 18 0 to +27
Up to 30 0 to +33
Up to 35 0 to +39
Up to 50 0 to +39
Up to 80 0 to +46 +0.13 to +0.23 +0.20 to +0.35
Up to 120 0 to +54 +0.15 to +0.25 +0.20 to +0.35
Up to 180 0 to +63 +0.18 to +0.28 +0.25 to +0.45
Up to 250 0 to +72 +0.20 to +0.30 +0.25 to +0.45
Up to 300 0 to +81
Up to 315 0 to +81 +0.23 to +0.35 +0.30 to +0.55
Up to 400 0 to +89

 

 

Factors in Seals Selection

 

Types of Motion

Types Choices

Rotation

Any type of seal other than TX4
Reciprocating TX4 seals (TC4, TB4.....)

 

 

Media

Media Choices
Regular lubricants Regular seals
Water, non lubrication liquids Using two single-lip seals with grease or lubricants in between. 
Chemicals When sealing element material is not acceptable, try mechanical seal.

 

 

 Pressure

 

 

 

Existence of Dust

Environment Choice
No Dust Single-lip Seals ( S Type) 
Dust Double-lip Seals ( T Type) 


 

 

Temperature

 

Cautions on Assembly

 

Bore The leading edge must be deburred. A rounded corner or chamfer should be provided.
Shaft Remove surface nicks, burrs, grooves, and spiral machine leads.
Shaft End Remove burrs or sharp edges. The shaft end should be chamfered in applications where the shaft enters the seal against the sealing lip.
Dimensions Be sure that the shaft and bore diameters match those specified for the seal selected. Damage may have occurred prior to installation. A Seal sealing lip that is turned back, cut, or otherwise damaged should be replaced. 
Seal Direction  Make sure that the new seal faces in the same direction as the original one. Generally, the lip faces the lubricant or the fluid to be retained.
Correct Tools Press fitting tools should have an outside diameter of 0.3 mm smaller than the bore size. For the best results, the center of the tool should be open so the pressure is applied only at the outer edge. 
Pre-lubricate Before installation, wipe the sealing element with the lubricant being retained. 
Proper Force Use proper driving force, such as a soft-face tool, arbor press, or wood. Apply force evenly around the outer edge to avoid cocking the seal. 



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