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Sandwich Structure Applications

Lightweight and stiff, sandwich panels are a vital element of many modern aircraft interior designs. Reinforcing and edge finishing of such panels can be costly and time consuming, but it is essential.

The cabin environment applications also have a supplementary need of fulfilling stringent fire, smoke and toxic gas emission (FST) regulations, which greatly limits the number of acceptable solutions in this area.

3M offers a wide and modern product portfolio suitable for all kind of applications on sandwich panels and structures both for interiors and aero-structures.

Sandwich Structure Application

The escalated importance of weight saving to obtain reduction of fuel consumption combined with manufacturing of complex shaped parts increases the need for composite honeycomb and sandwich constructions in aircraft manufacturing.

Although they are light and stiff, honeycomb sandwich structures need local reinforcement in load-bearing areas or in fixation spots like inserts. Naturally, open sandwich edges need reinforcement and protection as well to prevent from impact damages and moisture ingress.

For this purpose 3M have several products that are easy to use manually or automatically and can be cured either at room temperature or standard aerospace cure temperatures of 120°C / 180°C. 3M low density core fillers ensure high performance in the application with minimized addition of weight to the final structure. Since many of the 3M low density void fillers offer full stand alone FST performance, 3M's potting compounds can solve the aerospace industry interiors manufacturing main compliance issue of their final parts.

Typical applications are honeycomb sandwich edge close out, local reinforcement where inserts or fasteners are needed later in the process and the splicing of honeycomb and sandwich cores.

Core Splicing & Edge Finishing

Our Scotch-Weld core splice adhesive films are designed to be cured in typical industry cure cycles 120°C - 180°C.", low density, expandable, epoxy based products. They are mainly meant to fill mismatched areas and gaps, splice honeycomb cores and finish edges of sandwich panels. They are co-curable with structural adhesive films and composite prepregs and help save time in manufacturing by eliminating post-cure finishing activities.

Due to their low density the weight increase is minimal. 3M’s core splice films offer excellent gap filling capabilities and at the same time due to an expansion of up to 150% provide a strong, safe and durable bond.

Typically, these kind of applications are used for aero-structures like:

  • Landing gear doors,
  • Flap track fairings and spoilers,
  • Engine environment structures like fan case panels and nacelle structures
  • Interiors, like overhead stowage compartments, partition walls, ceiling panels and galley structures.

Core reinforcement

3M Scotch-Weld™ low density void fillers can be used to locally reinforce honeycomb or for closing edges of sandwich panels. The heat or room temperature curing products can either be cured apart or co-cured with the surrounding materials (composite prepregs, core splice films, film adhesives). As the cured filler is easily machinable and sandable, a cutting of a panel in a reinforced area enables a clean edge finish.

3M void fillers save production time and labour cost as they reduce further manufacturing steps for the sandwich structure. Due to their very low density, they can reduce weight of cabin furnishing. With their halogen-free FST system an improvement in operator health and safety during application is improved.

Typically, these types of applications are used for aero-structures like landing gear doors, flap track fairings and spoilers, for engine environment structures like fan track fairings and nacelle structures and for interiors like overhead stowage compartments, partition walls, ceiling panels, galley and lavatory structures.

To discuss any of these issues with a representative of the Aerospace group, please contact us