Understanding Oil Seal Tolerances and Specification Tables
Achieving a perfect seal requires precise coordination between the shaft, the housing bore, and the seal dimensions. Improper fitment—whether too tight or too loose—is the leading cause of seal failure and equipment downtime.
The following reference tables provide the industrial standard design tolerances for both Imperial (inch) and Metric (mm) systems. Please refer to these guidelines to ensure optimal press-fit interference and long-term sealing performance.
- Tables 1 & 2: Shaft Diameter Tolerances (Ensures lip contact and prevents wear).
TABLE 1. SHAFT TOLERANCE (IMPERIAL)
| NOMINAL SHAFT DIAMETER | TOLERANCE |
|---|---|
| up to 4.000 | ± 0.003 |
| over 4.000 to 6.000 | ± 0.004 |
| over 6.000 to 10.000 | ± 0.005 |
| over 10.000 | ± 0.006 |
TABLE 2. SHAFT TOLERANCE (METRIC)
| SHAFT DIA. (mm) | TOLERANCE in µm | |
|---|---|---|
| Lower | upper | |
| over 0 to 3 | 0 | -60 |
| over 3 to 6 | 0 | -75 |
| over 6 to 10 | 0 | -90 |
| over 10 to 18 | 0 | -110 |
| over 18 to 30 | 0 | -130 |
| over 30 to 50 | 0 | -160 |
| over 50 to 80 | 0 | -190 |
| over 80 to 120 | 0 | -220 |
| over 120 to 180 | 0 | -250 |
| over 180 to 250 | 0 | -290 |
| over 250 to 315 | 0 | -320 |
| over 315 to 400 | 0 | -360 |
| over 400 to 500 | 0 | -400 |
Tables 3 & 4: Housing Bore Tolerances (Ensures the seal remains securely in place).
TABLE 3. HOUSING TOLERANCE (IMPERIAL)
| BORE DIA. (inch) | BORE TOLERANCE |
|---|---|
| up to 3.000 | ± 0.0010 |
| 3.001 to 6.000 | ± 0.0015 |
| 6.001 to 10.000 | ± 0.0020 |
| 10.001 to 20.000 | + 0.002 / -0.004 |
| 20.001 to 40.000 | + 0.002 / -0.006 |
| 40.001 to 60.000 | + 0.002 / -0.010 |
TABLE 4. HOUSING TOLERANCE (METRIC)
| BORE DIA. (mm) | BORE TOLERANCE |
|---|---|
| Over 6 to 10 | + 0.022 / -0.000 |
| Over 10 to 18 | + 0.027 / -0.000 |
| Over 18 to 30 | + 0.033 / -0.000 |
| Over 30 to 50 | + 0.039 / -0.000 |
| Over 50 to 80 | + 0.046 / -0.000 |
| Over 80 to 120 | + 0.054 / -0.000 |
| Over 120 to 180 | + 0.063 / -0.000 |
| Over 180 to 250 | + 0.072 / -0.000 |
| Over 250 to 315 | + 0.081 / -0.000 |
| Over 315 to 400 | + 0.089 / -0.000 |
| Over 400 to 500 | + 0.097 / -0.000 |
Tables 5 & 6: Seal O.D. Interference & Roundness.
TABLE 5. TOLERANCE OF SEAL O.D (IMPERIAL)
| METAL O.D | |||
|---|---|---|---|
| BORE | INTERFERENCE | TOLERANCE | ROUNDNESS |
| ~1.000 | + 0.004 | ± 0.002 | 0.005 |
| 1.001~2.000 | + 0.004 | ± 0.002 | 0.006 |
| 2.001~3.000 | + 0.004 | ± 0.002 | 0.006 |
| 3.001~4.000 | + 0.005 | ± 0.002 | 0.007 |
| 10.001~20.000 | + 0.008 | + 0.006/-0.002 | 0.2% of O.D |
TABLE 6. TOLERANCE OF WIDTH (IMPERIAL)
| WIDTH | TOLERANCE |
|---|---|
| ALL SIZE | ± 0.015 |
TABLE 7. TOLERANCE OF SEAL O.D (METRIC)
| METAL O.D | ||
|---|---|---|
| BORE | TOLERANCE | ROUNDNESS |
| ~10.00 | + 0.20/+ 0.10 | 0.10 |
| 180.01~250.00 | + 0.30/+ 0.20 | 0.38 |
| 300.01~400.00 | + 0.35/+ 0.23 | 0.2% of O.D |
TABLE 8. TOLERANCE OF WIDTH (METRIC)
| WIDTH | TOLERANCE |
|---|---|
| ≤10.00 | ± 0.20 |
| OVER 10.01 | ± 0.30 |
TABLE 9. SPECIFICATION OF METALLIC INSERT AND GARTER SPRING
| STANDARD | SAE No. | DIN No. | MATERIAL |
|---|---|---|---|
| METALLIC INSERT | 1008-1010 | 1624 | Carbon Steel |
| GARTER SPRING | 1070-1090 | 17223 | Carbon Steel |
Need Precise Tolerances for Critical Applications?
Standard tables are a great starting point, but specialized machinery often requires custom fits. At Wintek, we manufacture oil seals with precision molding to meet tight tolerance specifications.