7.1.1 Elastomer and Plastic Seals, Compression Packing

Abrasion resistance Ability of a material to resist abrasive wear.

Ageing Change in characteristics of rubbers with time specifically influenced by environmental factors, e.g. light, heat, etc.

Anaerobic A term used to describe materials that remain liquid while exposed to air, yet harden when confined between close fitting parts.

Anti-extrusion ring A ring of material that is harder than the seal, installed on the low pressure side to prevent extrusion of the seal material into the clearance gap.

Anti-oxidant An ingredient used when compounding rubber to suppress oxidation of the rubber.

Asperities On a microscopic scale, high spots of surface roughness produced by normal machining or finishing processes.

Backup ring See Anti-extrusion ring.

Bedding-in A period of running-in when sealing lips or surfaces develop intimate contact. Often a period of high seal wear rate.

Bloom A cloudy or milky white discolouration appearing on the surface of elastomer components after storage.

Braid Hollow or solid structure of round, square or polygonal section constructed from interlocking filaments or yarn strand laid obliquely to the axis of the braid.

Breakaway friction See Static friction.

Breakout friction See Static friction.

Cold flow A continued deformation with time...