How to choose materials
When selecting rubber materials for sealing, there are a number of important selection criteria to be considered:
The service conditions to be considered include:
1) Fluid to be sealed (including any liquid, gas, solid, and kinds of chemical solutions).
2) Temperature range (the minimum and maximum operating temperature).
3) Pressure range (the compression/decompression rate when the pressure is high).
4) Motion - either static or dynamic.
The design requirements to be considered include:
1) Component geometry/description, like O-ring, gasket, diaphragm, etc.
2) The effect of chemical/fluid media on the seal.
3) Desired service life. Find out the reason and which material was used for a failed seal.
4) Lubrication level and assembly methods, including lubricants, installed stretch, etc.
5) Critical dimensions and tolerances, including groove dimensions and machining tolerances.
The inspection requirements to be considered include:
1) Defining inspection criteria.
2) Determining the need for lot sampling.
3) Setting acceptable quality levels (AQLs).
4) Indicating the critical sealing surface.
The selection of material specification:
1) Define material specifications, such as the American ASTM, German DIN, Japanese JIS, Chinese GB.
2) Discuss with your supplier to specify sealing materials.
3) Choose suppliers with stable quality and delivery.
Select suitable rather than high-cost and impractical rubber materials that results in poor sealing performance in end
product. Rubber, whether natural or synthetic, has the general characteristics of rubber, such as resilience after
compression, tortuous resistance, squeeze resistance, and resistance to gas and liquid permeability. However, each rubber
elastomer has its unique properties and can be formulated into a composition which causes an influence on the
performance. Currently there are more than 20 kinds of rubber elastomers widely used in various material needs. In
addition, rubber elastomers could meet all engineering requirements through formula design and mix chain by
professional mix-chain factories. The curing effect could transfer the thermoplastic rubber mixtures to thermosetting
rubber with an expectable shape. The crosslink effect provides the linking strength and elasticity of rubber molecular to
display sealing function. Thus, it is crucial for sealing designers, manufacturers, and rubber material suppliers to discuss
and determine applicable materials.
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