F

Face Seal

Squeezed, like a gasket, on both the top and bottom surfaces of the seal's cross section. An axial seal.

FDA

Food and Drug Administration is a U.S. government agency that regulates the ingredients in rubber compounds that are intended for use in food and medical applications.

Filler

A finely divided material used to reinforce or modify elastomer physical properties, impart certain processing properties, or reduce cost. Typical examples are carbon black, clays, calcium carbonates and silicas.

Flash

Excess rubber around a molded part due to cavity overflow and/or parting line of molded surfaces.

Flex Resistance

The ability of an elastomeric product to resist the stress of constant bending.

Flow Lines

Molded article surface imperfections caused by failure of the rubber stock to blend with itself during the molding operation.

Fluid

A liquid or gas.

Friction (Break-Out)

Friction developed in dynamic seal situations during machine start-up. When machine operation is irregular, O-rings tend to conform (adhere) to the microfine grooves of surrounding glandular surfaces, requiring extra initial force to break them out of these microfine grooves.