A bonded seal is a type of

washer Washer most commonly refers to: *Washer (hardware), a thin usually disc-shaped plate with a hole in the middle typically used with a bolt or nut *Washing machine, for cleaning clothes Washer may also refer to: *Dishwasher, a machine for cleani ...

used to provide a

seal Seal may refer to any of the following: Common uses * Pinniped, a diverse group of semi-aquatic marine mammals, many of which are commonly called seals, particularly: ** Earless seal, or "true seal" ** Fur seal * Seal (emblem), a device to impr ...

around a screw or bolt. Originally made by Dowty Group, they are also known as Dowty seals or Dowty washers. Now widely manufactured, they are available in a range of standard sizes and materials Dowty Seal taken over by Trelleborg sealing solutions. Bonded Seals are made by Trelleborg in the United Kingdom to the original specification. A bonded seal consists of an outer annular ring of a hard material, typically steel, and an inner annular ring of an elastomeric material that acts as a

gasket Some seals and gaskets A gasket is a mechanical seal which fills the space between two or more mating surfaces, generally to prevent leakage from or into the joined objects while under compression. It is a deformable material that is used to c ...

. It is the compression of the elastomeric part between the faces of the parts on either side of the bonded seal that provides the sealing action. The elastomeric material, typically nitrile rubber, is bonded by heat and pressure to the outer ring, which holds it in place. This structure increases resistance to bursting, increasing the pressure rating of the seal. Because the bonded seal itself acts to retain the gasket material, there is no need for the parts to be sealed to be shaped to retain the gasket. This results in simplified machining and greater ease of use as compared to some other seals, such as

O-ring An O-ring, also known as a packing or a toric joint, is a mechanical gasket in the shape of a torus; it is a loop of elastomer with a round cross-section, designed to be seated in a groove and compressed during assembly between two or more par ...

s. Some designs come with an additional flap of rubber on the internal diameter to locate the bonded seal at the centre of the hole, these are called self-centring bonded washers

References

Seals (mechanical) {{Mech-engineering-stub