O-ringsare often used in a variety of industries, including automotive, aerospace, and manufacturing. They are rings made of different materials and used to seal two or more components together. Materials used to make O-rings are important factors in determining their effectiveness and robustness. In this paper, we will discuss the different types of materials used to make the O-rings.

　　1. Nitrile rubber (NBR) Nitrile rubber is one of the commonly used materials in O-ring. It is a synthetic rubber, resistant to oil, fuels, and other chemicals. Nitrile rubber O-rings are also heat and wear resistant, making it ideal for automotive and industrial applications.

　　2. Fluorine rubber (FKM) fluorocarbon, also known as Viton, is a high-performance material used in O-rings. It is resistant to high temperature, chemicals and fuels. CFFC O-rings are commonly used in aerospace and industrial applications in the presence of high temperature and irritant chemicals.

　　3. Silicone gel (VMQ) Silicone rubber is a kind of heat resistance, cold resistance, ozone resistance of synthetic rubber. It is also waterproof and steam-proof, making it ideal for food and medical applications. Silicone O-rings are commonly used in the pharmaceutical and food processing industries.

　　4. ethylene propylene rubber (EPDM) ethylene propylene rubber is a kind of synthetic rubber resistant to weathering, ozone and chemicals. The EPDM O-rings are commonly used for automotive and industrial applications exposed to harsh environments.

　　5. Polyurethane (PU) Polyurethane is a synthetic material resistant to wear, tear and impact. PUO-rings are usually used for hydraulic and pneumatic applications in the presence of high pressure and high speed.

　　6. Neoprene (CR) Neoprene is a synthetic rubber resistant to oil, fuel and chemicals. It is also resistant to ozone and weathering. Neoprene O-rings are commonly used in automotive and industrial applications.

　　The O-rings are made from different materials according to the application. The materials used determine the chemical resistance, heat resistance, and wear resistance of the O-rings. It is important to select the right material for specific applications to ensure the effectiveness and durability of the O-rings.