A washer like device of a relatively hard material placed in the gland between the o-ring and groove side wall, also called a back up ring. Blemish: Deformity on the surface of a molded product.    Brittleness: The tendency to crack when deformed. BUNA N: A general term for the copolymer butadiene and acrylonitrile also referred to as NBR or Nitril [..]

Average material expansion per one degree change in temperature, expressed as a fraction of the initial dimension. Cold Flexibility: O-Ring flexibility (resistance to cracking and breaking) at low temperatures. Cold Resistant: The ability of an o-ring to function at low temperatures. Compound: A mixture of an elastomer and other ingredients to prod [..]

A three digit number preceded by a dash as specified by SAE Aerospace Standard 568A to indicate the -o-ring size based on inside diameter (I.D) and cross-section (W). Deflashing: Any of various processes used to remove the waste edge from a molded rubber part. Diametral Clearance Gap:  The difference in diameters between two mating surfaces. Differ [..]

The tendency of a material to return to its original shape after deformation. Elastomer: A general term used to describe both natural and synthetic polymers possessing the resilience to return to ---its original shape after deformation. Elongation: Percentage increase in original length of a specimen produced by a tensile force applied to the speci [..]

Front surface of a seal. Filler: Relatively inexpensive and inert material added to an elastomer to reinforce or modify properties. Flash: The excess material protruding from the surface of a molded part at the mold junctions. Flaws: Surface imperfections that occur infrequently. Flexural Strength: Ability of a material to flex without permanent di [..]

Static seal effected when a deformable material is sandwiched and compressed between two mating surfaces. Gates: The openings in an injection or transfer mold that ensure even flow into the cavity. Gate Mark: A raised spot or small depression on the surface of an injection or transfer molded part where gates interface the cavity. Gland: Complete ca [..]

Measurement of the resistance to penetration of an indenture into a cured rubber sample. Heat Aging: Loss of physical properties as a result of exposure to heat. Heat Resistance: Rubber compounds capacity to undergo exposure to some specified level of elevated temperature and retain a high level of its original properties. Heteropolymer: polymer co [..]

The inside diameter of an o-ring Injection Molding: Process where preheated rubber is injected under pressure through a series of runners and into a closed mold cavity.

The rate at which a fluid passes through a barrier. Life Test: A laboratory test of the amount and duration of a products resistance to destructive forces. Low Temperature Flexibility: The ability of an elastomeric product to be flexed at low temperatures without cracking.

Points where different parts of an assembly meet. Memory: Ability of an elastomeric material to return to its original shape after deformation. Modulus of Elasticity: Ratio of the stress to the strain as measured on a rubber specimen. Mold Cavity: Hollow space of the mold within which the uncured rubber compound is shaped and cured to the desired s [..]