Meeting safety requirements in all aspects of aerospace production and engineering demands high levels of expertise. Now, specialist technology company 3M has developed what it believes to be the world’s first two-part structural epoxy adhesive to meet aerospace fire, smoke, and toxicity (FST) standards (when tested stand-alone) without the need for additional treatments or surface coatings.
The adhesive has been developed to meet the requirements of FAR 25.853 (a) flaming mode, JAR 25.853 (a) flaming mode, and ABD 0031 & AITM 2.0002A as defined by the U.S. flight authorities, European flight authorities, and Airbus, respectively.
Scotch-Weld adhesive 7246-2 B/A FST is aimed at simplifying many aircraft interior manufacturing tasks by allowing builders to complete assembly and FST compatibility operations in one step. The product will replace several types of conventional adhesive, simplifying stock requirements and improving productivity.
Scotch-Weld adhesive 7246-2 B/A FST is a room-temperature-curing structural two-part epoxy paste adhesive system. Its thixotropic, non-sag formulation makes it easy to apply without dripping or deformation, says 3M. The product has been created for many aerospace interior tasks, such as the corner splicing of honeycomb panels, insert bonding, and the bonding of tubular ducting. It allows completed assemblies to meet FST requirements without additional surface treatment. Light tan in color to match conventional honeycomb skin materials, the material can be over painted using the same surface coatings as the panels without leaving shadows.
“Our aerospace customers need to produce assemblies that meet extremely demanding FST standards,” said John Lester, Key Account Manager at 3M. “Until now, those requirements have precluded them from taking advantage of modern easy-to-use structural epoxy adhesives where the adhesive will form part of the outer surface of the finished product.”
The adhesive has a typical work life of 45 min and reaches handling strength in 3-4 h under the same conditions.
The product is available in an EPX duo-pack cartridge or in bulk containers for hand mixing or use with automated mixing equipment. Compatible with most common aerospace interior substrates, including aluminum honeycomb, polycarbonate, glass/phenolic panels, polyetherimide, and polyphenylsulfone, Scotch-Weld adhesive 7246-2 B/A FST is resistant to damage by water, salt spray, jet fuel, and mineral oils.