Press Fit Allowance & Permissible Eccentricity

The oil seal's metal case is designed to be press-fitted into the housing bore with a controlled interference. Too little interference allows the seal to creep out under pressure; too much can distort the case and change the lip geometry.

Bore Diameter (mm)	Bore Tolerance (H8)	Interference Fit (mm)	Surface Finish Ra (µm)
12 – 20	+0.033	0.04 – 0.10	1.6 – 3.2
20 – 30	+0.033	0.05 – 0.12	1.6 – 3.2
30 – 50	+0.039	0.06 – 0.15	1.6 – 3.2
50 – 80	+0.046	0.07 – 0.18	1.6 – 3.2
80 – 120	+0.054	0.09 – 0.22	1.6 – 3.2
120 – 180	+0.063	0.10 – 0.25	1.6 – 3.2
180 – 250	+0.072	0.12 – 0.30	1.6 – 3.2
250 – 315	+0.081	0.14 – 0.35	1.6 – 3.2
315 – 400	+0.089	0.16 – 0.40	1.6 – 3.2

Note: Rubber-covered OD seals (SC, SB, VC types) are more tolerant of bore finish imperfections and provide their own static bore seal.

The sealing lip can follow a limited amount of shaft eccentricity (dynamic run-out) without losing contact. The garter spring compensates for minor run-out, but beyond these limits the lip lifts off the shaft on one side, creating a leak path.

Shaft Diameter (mm)	Max Speed (RPM)	Permissible Eccentricity e (mm)
10 – 30	≤ 3000	0.15
10 – 30	≤ 1500	0.25
30 – 80	≤ 3000	0.20
30 – 80	≤ 1500	0.30
80 – 150	≤ 1500	0.35
80 – 150	≤ 500	0.50
150 – 300	≤ 500	0.50
> 300	≤ 500	0.60

Values are guidelines for standard elastomer lip seals with garter spring. PTFE lip seals have lower eccentricity tolerance due to the rigid lip material.

Bore Diameter (mm)	Chamfer Angle	Chamfer Depth (mm)
12 – 50	15° – 30°	1.0 – 1.5
50 – 120	15° – 30°	1.5 – 2.0
120 – 250	15° – 25°	2.0 – 3.0
> 250	15° – 20°	3.0 – 4.0