Groove Design for Metric ISO Size O-Rings per. ISO 3601-2

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Groove Design for Metric ISO Size O-Rings per. ISO 3601-2

Fluids, Piping and Hydraulic Design Data

An initial compression (squeeze) of the O-Ring in the groove is essential to ensure its function as a primary or secondary sealing element. It serves to:

- Achieve the initial sealing capability
- Bridge production tolerances
- Assure defined frictional forces
- Compensate for the compression set
- Compensate for wear Depending on the application, the following values apply for the initial squeeze as a proportion of the cross section (d₂):

Dynamic applications: 6 to 20%
Static applications: 15 to 30%

The design of the grooves can be based on the guide values for the initial squeeze shown in the diagrams in Figure 1 and 2. These take into account the relationship between loads and cross sections according to ISO 3601-2 (version 1987).

Figure 1, Permissible range of initial squeeze as a function of cross section, radial dynamic

Figure 2, Permissible range of Initial squeeze as a function of cross section, radial static and axial

Shaft and bores

Figure 3, Lead-in chamfers for bores, tubes

Figure 4 Lead-in chamfers for shafts, rods

Table 1, Lead Lead-in Chamfers

Lead-in chamfers length Z min.		O-Ring cross section d₂
15°	20°
2.5	2.0	up to 1.78 1.80
3.5	2.5	up to 2.62 2.65
4.5	3.5	up to 3.53 3.55
5.0	4.0	up to 5.33 5.30
6.0	4.5	up to 7.00

The surface roughness of a lead-in chamfer is:
R_Z ≤ 6.3 µm
Ra ≤ 0.8 µm

The tolerances given in table XV and the maximum permissible radial clearance S (extrusion gap) given in the table XII must be maintained.

If the clearance is too large, there is a risk of seal extrusion which can result in the destruction of the O-Ring

Figure 5 Radial clearance “S“

Figure 6, O-Ring installation recommendations

This Chart Calculator Specifies Groove design for o-ring sizes ranging from 0.5 to 12.00 mm per. ISO 3601-2. (Premium Membership required)

Preview: Groove design for o-ring sizes table calculator

1) When using Back-up Rings the groove is to be widened by the corresponding Back-up Ring thickness (b2: one Back-up Ring, b3: two Back-up Rings).
2) If a Back-up Ring is used the recommended radius r1 should always be r1= 0.25 ±0.2mm.

Reference:

ISO 3601-2, (Version 1987)