This specification establishes adhesive performance requirements and the procedures to determine the locking ability of preapplied adhesive coatings on externally threaded fasteners. This specification is written for the purpose of identifying and controlling key material properties of adhesive coated externally threaded fasteners.

Material Description. Two grades of material are covered by this specification. In addition to the regular grade, this specification describes a temperature resistant material that retains locking ability at 200⁰C, while also conforming to the regular requirements of this specification.

Material Identification. These materials are designated with the following GM numbers:

GM6175M Max temperature 135⁰C

GM6194M Max temperature 200⁰C

Typical Application. This specification is for externally threaded fasteners that require a pre-applied adhesive for chemical locking to prevent self loosening due to shock and vibration. Fasteners with these materials shall not be reused.

A third GM preapplied thread locking specification, GM6124M, is available for fasteners that require lower thread locking performance.

Remarks.

The preapplied thread locking adhesive compounds are dry to the tough and remain inert on externally threaded fasteners until they are engaged into the mating internal thread. The shearing action or forces of assembly activate the adhesive, which after proper curing time and temperature, harden to form a chemical bond between the mating threads. This chemical adhesive bond prevents fasteners loosening from shock and vibration. The adhesive shall be dry to tough when properly applied and be compatible with automatic feed equipment used in the installation of fasteners. The applied compound shall have no adverse effect on the health of personnel when used for its intended purpose.