They have high pressure sealing and gasket functions that both work the same as standard O-rings and are even able to fit into the same gland.
Flat O-Rings – Arizona Sealing Devices, Inc.
Flat O-rings work in the same fashion as other o-rings, although they do perform better in applications like rotary sealing. That is because their shape is specialized for certain shapes and applications. They are also often found in hydraulic and pneumatic machinery and equipment. The industries that utilize o-rings include aerospace, oil refineries, chemical processing and water treatment facilities, jewelry manufacturers and jewelry suppliers.
Flat o-rings work as seals when placed between two parts of a machine body while it is being assembled, just like clear o-rings. Unlike some o-ring brands, these square shaped o-rings require less squeezing and pressure to maintain an adequate seal, and therefore use less friction, cutting down on wear and tear. This results in an extended life, especially where abrasion from contacting surfaces is a common issue. Less friction also means flat o-rings do not require lubricants to protect them, which cuts down on upkeep costs as well.
O-rings that are flat or have square and rectangle cross sections are either extruded out of a square-shaped mold or cut from extruded tubes. They obtain their unique shape by curing processes and knife cutting or trimming. Curing involves changing the chemical body of an object with an addition of foreign chemicals into the melted form of the plastic used to construct the o-ring.
Cutting and trimming are done with machines equipped with specially shaped blades to cut the exact design of a flat o-ring numerous times, which is also known as die cutting. Flat o-rings are manufactured from all the same elastomeric rubber and thermoplastic materials as round o-rings, like silicone, Teflon and Viton. However, the four-lobed design of flat o-rings provides twice the sealing surface of regular O-rings.
Flat O-rings keep their smooth surface texture, tensile strength, thermal conductivity, wide temperature range and sealing ability under high pressure, but they are less common because of the uncommon manufacturing process that requires an additional step. Most other styles of O-rings simply require the molding process.