GMNA GM1131M PDF

This specification covers the more common types of sealing materials used in conjunction with fasteners (screws, nuts, and attaching clips), which are assembled into attachment holes in sheet metal. Holes intended to receive fasteners are generally designed with considerable clearance necessitating the use of a sealing material to fill the balance of the hole remaining after insertion of the fastener. Sealing materials for this service are required to prevent the penetration through the hole cavity of road splash, dust, etc.; also, to afford protection from corrosion where paint may have been chipped fro the edges of the hole during assembly.

Dependant on the end use, composition and application, the seals may be cut, molded, cast, or extruded. Normally these seals are specified as a preshaped, ready for use part and often assembled to the part for which they are designed.

This specification is intended to cover only basic requirements. More detailed requirements or individual applications shall be specified in engineering drawings. Purchase order and/or in other agreements between supplier and purchaser.

Material Description.

Material Identification. Materials fall into several composition categories as follows:

Type A. Compounded rubber base which may be vulcanizing or non-vulcanizing type and must be of a uniform composition.

Type A-1. Heat Resistant Composition similar to Type A. Sealer is to withstand reflow lacquer oven temperature schedule in addition to meeting all other requirements of this specification.

Type A-2. Heat Resistant Composition similar to Type A. Sealer is to withstand sustained temperatures of 205 C without losing its sealing qualities in addition to meeting all other requirements of this specification.

Type B. Plasticized reclaim rubber with cellulosic fiber filler that may be either extruded or die cut.

Type C and C-1. Synthetic rubber and wax composition.

Type D, E, F, G, and H. Closed cell sponge or foam types, usually made from vinyl plastisols, although other compositions are possible.

Type J. Closed cell neoprene sponge.

Type K. Composition, usually vinyl plastisol, is cast in place and subsequently cured. The finished seal is substantially solid as distinct from foam types.