What are the specific effects of the material characteristics of the sealing ring on the slot size?

The material characteristics of the sealing ring have a specific impact on the size of the slot, which is mainly reflected in the thermal expansion, hardness and compression, chemical resistance, wear resistance, elastic recovery ability and creep resistance of the material. Here's the breakdown:

1. Thermal expansibility

Influence: The thermal expansion coefficient of different materials is significantly different. For example, the thermal expansion coefficient of silicone rubber is high, and the volume expansion of the sealing ring is obvious when the temperature rises. The thermal expansion coefficient of polytetrafluoroethylene (PTFE) is low, and the size change is small.

Design Suggestions:

For materials with large coefficient of thermal expansion, the width and depth of the groove should be appropriately increased to reserve expansion space.

Under high temperature conditions, the groove size should be compensated according to the thermal expansion coefficient of the material.

2. Hardness and compression

Influence: The hardness of the sealing ring directly affects its compression rate and sealing performance. Materials with low hardness (such as nitrile rubber) are easy to be compressed, and the depth of the groove should be reduced accordingly. Materials with higher hardness (such as polyurethane) have low compression, and the groove depth needs to be appropriately increased.

Design Suggestions:

Select the appropriate compression rate (usually 15%-30%) according to the hardness of the seal ring, and adjust the groove depth accordingly.

Materials with higher hardness may require a smoother groove surface to reduce friction and wear.

3. Chemical resistance

Impact: The seal material must be compatible with the working medium. If the material reacts with the medium, it may cause the sealing ring to expand, dissolve or harden, which affects the fit of the slot size. For example, fluororubbers (FKM) are well resistant to most chemical media, while nitrile butadiene rubber (NBR) swells easily in polar solvents.

Design Suggestions:

Select a seal material that is compatible with the medium and refer to the chemical compatibility data provided by the material supplier.

For highly corrosive media, special coatings or protective measures are required to prevent changes in tank size.

4. Wear resistance

Impact: In a dynamic seal, there is relative movement between the seal ring and the groove surface. If the wear resistance of the material is poor, it may lead to the wear of the sealing ring, and then affect the fit of the groove size and the sealing performance. For example, polyurethane (PU) has better wear resistance than nitrile rubber.

Design Suggestions:

Select materials with good wear resistance and optimize the roughness of the tank surface to reduce friction and wear.

For high-speed movement or high-pressure conditions, it is necessary to consider the wear limit of the material, and reserve a wear margin.

5. Resilience

Impact: The sealing ring needs to have sufficient elastic recovery ability after compression to ensure long-term sealing performance. If the elastic recovery ability of the material is poor, the sealing ring may be deformed in the groove, affecting the sealing effect. For example, the elastic resilience of silicone rubber is better than that of EPDM.

Design Suggestions:

Select materials with good elastic recovery ability, and ensure that the groove size design is reasonable to avoid excessive compression resulting in permanent deformation of the material.

For high temperature or high pressure conditions, it is necessary to consider the change of elastic modulus of the material, and adjust the groove size to compensate.

6. Creep resistance

Impact: Under long-term pressure or high temperature environment, the sealing material may creep, resulting in dimensional changes. For example, nitrile butadiene rubber is prone to creep at high temperatures, while fluorine rubber has better creep resistance.

Design Suggestions:

Select materials with good creep resistance and refer to the service life data provided by the material supplier.

For seals used for a long time, it is necessary to check the groove size and seal status regularly, and replace them if necessary.

7. Matching of material thickness and slot width

Influence: The thickness of the sealing ring directly affects the design of the groove width. If the groove width is too narrow, it may cause difficulty in installing the seal ring or uneven compression. If the slot width is too wide, the sealing ring may shake in the slot, affecting the sealing performance.

Design Suggestions:

Select the appropriate groove width according to the thickness of the sealing ring, usually the groove width should be slightly larger than the thickness of the sealing ring to ensure easy installation and uniform compression.

For special shape seals (such as O-rings and V-rings), refer to the relevant standards (such as AS568, ISO 3601) for slot size design.

8. The relationship between material hardness and groove depth

Influence: The hardness of the sealing ring is closely related to the depth of the groove. The material with low hardness is easy to be compressed, and the groove depth should be appropriately reduced; Materials with higher hardness have lower compression, and the groove depth needs to be appropriately increased.

Design Suggestions:

Select the appropriate groove depth according to the hardness of the sealing ring to ensure that the sealing ring is compressed evenly in the groove and the sealing performance is good.

For high-hardness materials, it is necessary to consider the compression limit of the material to avoid excessive compression resulting in material damage.

The material characteristics of the sealing ring have a decisive influence on the groove size design. It is necessary to consider the thermal expansion, hardness, chemical resistance, wear resistance, elastic recovery ability and other factors of the material in the design to ensure that the groove size matches the material characteristics of the sealing ring, so as to achieve a reliable sealing effect.

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