In daily life, an o-ring is a very common sealing material applied in pumps, pipes, valves, automotive devices, etc. In the industrial field, the seal can play a role in preventing the leakage of lubricating oil and foreign invasion, which is particularly key to improving the airtightness of the product, so it is very important to choose the right silicone seal for your equipment.
But the nature of the o-ring, in a certain temperature, pressure, and different liquid or gas medium, will change. Different materials, lead to physical and chemical properties that are not the same. If the o-ring is used in rotating situations, the temperature rise caused by friction heat should be considered. Why the material difference will affect the performance and service life of the o-ring, we will analyze it from the following aspects.
• Speed of movement
The adaptability of different materials to the speed of mechanical motion is not the same. For static sealing, there is no relative movement between the seal and the sealed part, so the wear resistance and hardness of the material are not high requirements. But for dynamic seal, to be limited by its sealing speed and pressure, some ordinary materials, can not adapt to high-speed mechanical operation.
• Stress
The o-ring material is also very sensitive to working pressure. The material is different, and the pressure that the o-ring can bear is different. If the medium is raw material oil, the working pressure that it bears is smaller. If it is water, oil, and other mixed liquids, the working pressure is beyond the scope of the material, which will not only lead to leakage but also reduce the service life of the sealing ring.
• Temperature
Temperature also has a great impact on the material of the o-ring the temperature is too high or too low is not good, too high will make the tensile degree and the hardness of the o-ring reduce; If the temperature is too low, it will make the seal ring very brittle and easy to crack. Each kind of o-ring material has its suitable temperature range, in the design of material selection must pay attention.
• Medium compatibility
The compatibility of the two mediums has a very important role in the selection of seal materials. Some materials will be directly in contact with the medium. If there is no good compatibility between them, it will not only damage the o-ring but also pollute the sealing medium. Therefore, the material of the o-ring can not be eroded, nor can it produce chemical changes with the medium.
• Hardness
Material hardness is the most important index to evaluate the sealing performance, which determines the amount of tightening and groove extrusion gap, to prevent the plastic deformation of the o-ring under pressure. High-hardness material is strong, in the sealing process due to the impact of the environment and force, there will be gaps.
• Sealing form
O-ring is an automatic bidirectional action, its pre-compression and initial sealing will increase with the improvement of the system pressure. General seals are installed in the groove, to ensure the sealing effect, and should be reserved for tightening, but it should be noted that in different use environments, pre-tightening is not the same. The type of load can be divided into the static seal and dynamic seal; According to the sealing use can be divided into holes, shaft, and rotary shafts, according to the installation, radial and axial are applied.
What Materials Are Commonly Used In O-ring Manufacturing?
Material is also a key factor. Common o-ring materials include silicone rubber, metal, plastic, rubber, rubber-coated metal, silicone-coated metal, rubber, nitrile rubber, fluorine rubber, EPDM rubber, neoprene rubber, butyl rubber, styrene-butadiene rubber, isoprene rubber, butadiene rubber and so on. What is the better material for o-ring manufacturing? O-rings of different materials have different functional characteristics. What material is better to choose according to the use environment of the o-ring?
(1) Silicone Rubber O-ring
Silicone rubber seal has excellent heat and cold resistance, also ozone resistance, atmospheric aging resistance, and insulation properties.
Silicone rubber o-ring: It is suitable for household appliances, such as electric water heaters, electric iron, microwave oven, etc. It is also suitable for all kinds of supplies in contact with the human body, such as kettles, water dispensers, and so on. But it is not recommended for use in most concentrated solvents, oils, concentrated acids, and sodium hydroxide. The general temperature range is -55~250 ℃.
(2) EPDM O-ring
EPDM o-ring has excellent comprehensive performance and good high-temperature resistance, which is very favorable to adapt to the complex construction environment and meet the sealing needs of different production processes and products.
EPDM rubber o-ring: It can be used for alcohol and ketone, but also can be used for high-temperature water vapor environment sealing. Suitable for sanitary equipment, automobile radiator, and automobile brake system. Not recommended for food use or exposure to mineral oils. The general temperature range is -55~150 ℃.
(3) NBR(Nitrile Butadiene Rubber) O-ring
It has good oil and solvent resistance wear resistance, aging resistance, and air tightness, but ozone resistance, electrical insulation, and cold resistance are poor. It is easy to be oxidized under the condition of aging and cracking phenomena.
NBR o-ring is suitable for use in petroleum hydraulic oil, ethylene glycol hydraulic oil, diester lubricating oil, gasoline, water, silicone grease, silicone oil, and other media. Do not apply to polar solvents such as ketones, ozone, nitro hydrocarbons, MEK, and chloroform. The general temperature range is -40~120 ℃.
(4) Fluorine Rubber O-ring
Excellent flame retardant, air tightness, high-temperature resistance, ozone resistance, climate resistance, oxidation resistance, and oil resistance is the best rubber. Its disadvantages of it include poor processing, high cost, poor cold resistance, low elasticity, and permeability.
Fluorine rubber o-ring can be used for mineral oil, fuel oil, hydraulic oil, aromatic, and many organic solvents and chemicals. It is commonly used in the automotive industry, chemical processes, aerospace, and many mission industries. The service temperature under static seal should be limited to about -26 ° C (-15 ° F) to 282 ° C (450 ° F). Although it can be used for a short time at 295 ° C, its service life will be shortened when the temperature exceeds 282 ° C. The most suitable temperature for use under a dynamic seal is between -15℃ and 280℃. Low temperatures can reach -40℃.
Of course, we still need to consider another point, which is size. Most customers will choose the used samples, but after a period of use, the original size of the o-ring will be greatly affected by temperature, pressure, wear, and other factors, so the sample selection can only be used as a reference. A better way is to measure the size of the metal groove where the seals are located, with higher accuracy.
Silicone O-ring Manufacturer & Custom Silicone O-ring
At present, there are various kinds of o-rings on the market, with various prices and uneven quality. To buy good quality sealing rings, you had better find a professional silicone manufacturer. After all, the selection process of the o-ring manufacturing should be careful.
For 17 years, we, a silicone manufacturer have been focused on the production and development of various types of silicone seals, silicone o-rings, silicone gaskets, and silicone strips. All of them are widely used in automotive, solar photovoltaic electronics, LED lamps, wind power generation, energy conservation and environmental protection, the metallurgical industry, aerospace science and technology, military equipment, pharmaceutical, chemical, medical, food, drying, electronics, textile, kitchen bathroom, printing, shipbuilding and other industries.
