O-RING Sealing Ring Design Standards

O-ring, also known as O-RING, is a type of rubber ring with a circular cross-sectional shape. O-ring is the most widely used sealing element in hydraulic and pneumatic systems. The O-ring has good sealing performance, which can be used for both static and dynamic sealing; Not only can it be used alone, but it is also a fundamental component of many combined sealing devices. It has a wide range of applications, and if the materials are selected properly, it can meet the requirements of various media and motion conditions.

O-shaped sealing ring is an extrusion type seal, and the basic working principle of the extrusion type seal is to rely on the elastic deformation of the sealing element to create contact pressure on the sealing contact surface. If the contact pressure is greater than the internal pressure of the sealed medium, no leakage will occur, otherwise, leakage will occur.

Design requirements:

1. Compression amount: about 15% to 30% static; Dynamic sealing is about 10%~15%. The larger the wire diameter, the lower the percentage value.

2. Elongation rate: Generally, the elongation rate is 1% -10%. The O-RING sealing situation where multiple parts are assembled into components and then connected through insertion, the elongation rate is 10% -15%.

3. Filling rate: Generally, the filling rate is taken as less than 90%. When the design is limited, it is allowed to explain clearly and not exceed 100%,

4. Slot width: approximately 1.3 * wire diameter (empirical value reference)

5. Clearance between shaft and hole: unilateral clearance less than 0.15mm. Structures that may experience force deflection should consider increasing the clearance to avoid friction caused by deflection.

6. Shaft tolerance: Generally, ± 0.1 is required, precision is required to be ± 0.05, and special requirements are required to be ± 0.025

7. Hole tolerance: Generally, ± 0.1 is required, precision is required to be ± 0.05, and special requirements are required to be ± 0.025

8. When assembling the product, the chamfer that O-RING passes through is taken as 70 degrees, referring to the national standard GB/T3452.3

9. O-RING groove bottom fillet radius: R0.2~0.4; ten

10. Notch rounded corners/chamfering: Rounded corner R0.2 for plastic parts, Make chamfer C0.2 for machine addition

11. If there is a structure with eccentric force, the impact on compression should be considered.

12. Material: NBR is more wear-resistant and oil resistant than EPDM, with a temperature resistance of 80 degrees Celsius. It is not recommended to use in boiling water environments; EPDM has better weather resistance than NBR; Use N7118F with strict requirements for water quality.


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