Summary of basic knowledge points of rubber sealing materials
|
Elastomer type Polyacrylate rubber Ethylene methyl acrylate rubber Polyurethane (ester) rubber Chloroprene rubber EPDM rubber EPDM rubber Polyurethane (ether) rubber Fluororubber Fluorosilicone rubber Perfluoroelastomer Tetrafluoroethylene propylene copolymer Hydrogenated nitrile rubber Butyl rubber Methyl phenyl silicone rubber Methyl phenyl vinyl silicone rubber Methyl vinyl silicone rubber Natural rubber Nitrile rubber Styrene butadiene rubber Carboxylated nitrile rubber |
Abbreviation ACM AEM AU CR EPM EPDM EU FPM(FKM) FMQ,FVMQ(FSR) FFKM FEPM(TPE/P) HNBR IIR MPQ MPVQ MVQ NR NBR SBR XNBR |
Operating temperature range of common elastomers
Temperature/℃
Recommended operating temperature range
Short-term extended operating temperature range
Applicable media for various types of rubber
|
Material |
Applicable media |
Operating temperature/°C For movement |
Operating temperature/°C Stationary |
Remark |
|
Nitrile rubber |
Mineral oil, gasoline, benzene |
80 |
-30~120 |
|
|
Neoprene |
Air, water, oxygen |
80 |
-40~120 |
Attention for moving use |
|
Butyl rubber |
Vegetable oil, weak acid, alkali |
80 |
-30~110 |
Large permanent deformation, not suitable for mineral oil |
|
Styrene Butadiene Rubber |
Alkali, vegetable oil, air, water |
80 |
-30~100 |
Not suitable for mineral oil |
|
Natural rubber |
Water, weak acid, weak base |
60 |
-30~90 |
Not suitable for mineral oil |
|
Silicone Rubber |
High/low temperature oil, mineral oil, vegetable oil, oxygen, weak acid, weak base |
-60~260 |
-60~260 |
Do not use steam, avoid using on moving parts |
|
Chlorosulfonated polyethylene |
High temperature oil, oxygen, ozone |
100 |
-10~150 |
Avoid using on moving areas |
|
Polyurethane rubber |
Water, Oil |
60 |
-30~80 |
Wear-resistant, but avoid high-speed use |
|
Fluororubber |
Hot oil, steam, air, inorganic acid, halogen solvents |
150 |
-20~200 |
|
|
Polytetrafluoroethylene |
Acids, alkalis, various solvents |
-100~260 |
Avoid using on moving areas |
Hardness selection
|
Hardness (SHOREA) |
Hardness (IRHD) |
Scope of application |
|
40+/-5 |
/ |
Highly sealed conditions are required for low pressure |
|
50+/-5 |
/ |
|
|
60+/-5 |
63+/-5 |
|
|
70+/-5 |
73+/-5 |
Normally sealed |
|
80+/-5 |
83+/-5 |
Sealing under high pressure |
|
90+/-5 |
93+/-5 |
1. Stress-life model (S-N curve)
The S-N curve (stress-life curve) describes the fatigue life of sealing materials at different stress levels. By experimentally measuring the number of fatigue failure cycles of materials at different stress amplitudes and drawing a stress-life curve, the durability of the seal can be predicted.
Suitable for seals that are subjected to long-term dynamic loads, such as reciprocating piston rod seals or rotating shaft seals.
2. Arrhenius aging model
This model is used to predict the aging life of seals in high temperature environments. By accelerating aging experiments at different temperatures, the changes in material properties (such as hardness, elasticity, and tensile strength) are measured, and the service life at room temperature is estimated.
Suitable for seals working in high temperature environments, such as engine oil seals and solar equipment seals.
3. Creep and Compression Set Analysis
Seals will deform under long-term pressure, which will eventually lead to seal failure. Creep tests and Compression Set tests can be used to predict the long-term sealing ability of seals.
4. Air tightness and leakage test
By filling gas or liquid, measure the leakage rate of the seal to determine its sealing performance.
Common methods: pressure decay test, helium leak test, water immersion test.
5. Low temperature flexibility test
Evaluate the elasticity and sealing of the seal in a low temperature environment to ensure that it will not become brittle or fail in extreme cold conditions.
