EPDM seals: basic properties and manufacturing process

1. Basic characteristics of EPDM

EPDM is a high molecular synthetic rubber copolymerized by ethylene, propylene and a small amount of non-conjugated dienes. Its unique molecular structure gives EPDM a variety of excellent physical and chemical properties, making it an ideal material for manufacturing high-performance seals.

1. Weather resistance

EPDM has excellent resistance to UV rays and weather aging. After long-term exposure to outdoor environments, EPDM seals can still maintain their elasticity and sealing properties, and are not prone to deterioration and embrittlement.

2. Weather resistance

EPDM can maintain stable physical and chemical properties over a wide temperature range (-50°C to 150°C), showing excellent weather resistance. This makes it suitable for use under extreme temperature conditions.

3. Ozone resistance

EPDM has extremely high resistance to ozone and is not prone to cracking and deterioration. This feature enables it to perform well outdoors and in harsh climate conditions.

4. Electrical insulation

EPDM has excellent electrical insulation properties and can provide reliable protection in electrical equipment and cable seals to ensure safe operation of the equipment.

5. Chemical resistance

EPDM has good tolerance to a variety of chemicals (such as water, acid, and alkali), but may swell or dissolve in certain polar solvents (such as ketones and esters).

2. Manufacturing process of EPDM seals

The manufacturing process of EPDM seals involves multiple key steps and technologies to ensure that the final product has excellent performance and reliability.

1. Raw material preparation

Raw material selection:

Ethylene, propylene, and non-conjugated dienes (such as dicyclopentadiene).

Various additives, such as vulcanizers (sulfur or peroxide), antioxidants, fillers (carbon black, white carbon black), plasticizers, lubricants, etc.

2. Mixing

Internal or open mixing:

Mix the EPDM raw rubber with various additives in an internal mixer or an open mixer to ensure that the components are evenly distributed.

Control the temperature and shear force during mixing to avoid overheating or excessive shearing that may cause material performance degradation.

3. Extrusion molding

Calendering or extrusion:

The mixed EPDM rubber compound is molded by a calender or extruder to form the preliminary shape of the O-ring.

Control the extrusion speed and temperature to ensure the cross-sectional shape and dimensional accuracy.

4. Vulcanization treatment

Vulcanization furnace or vulcanization tank:

Put the molded EPDM seal into a vulcanization furnace or vulcanization tank and vulcanize it under high temperature and pressure conditions.

The vulcanization conditions (temperature, time and pressure) depend on the specific rubber formula and product requirements. Generally, the vulcanization temperature is between 150°C and 200°C, and the vulcanization time ranges from a few minutes to a few hours.

5. Post-treatment

Cooling and trimming:

The vulcanized EPDM seal is cooled by a cooling water tank to make it solidify quickly.

The vulcanized seal is trimmed using a trimmer or grinder to remove burrs and excess material to ensure dimensional accuracy and surface quality.

6. Testing and Packaging

Performance Testing:

EPDM seals are subjected to various performance tests, such as hardness test, tensile strength test, ozone resistance test, compression set test, etc.

Seals that meet the requirements are packaged to prevent damage during storage and transportation.

III. Summary

EPDM is an ideal material for manufacturing high-performance seals due to its excellent weather resistance, weather resistance, ozone resistance and electrical insulation properties. Through precise manufacturing processes, including raw material preparation, mixing, extrusion molding, vulcanization and post-processing steps, EPDM seals are ensured to have excellent physical and chemical properties. These seals are widely used in many fields such as automobiles, construction, industrial equipment, and household appliances, providing reliable sealing protection for various equipment and systems.

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