Joined-up thinking with adhesives!

FACC1
FACC1

DELO’s technical product coordinator product management, Nicole Guggenmos reveals how one of the company’s customers relies on DELO adhesives for overhead stowage bins made of composite materials.

DELO Industrial Adhesives' technical product coordinator product management, Nicole Guggenmos reveals how one of the company’s customers relies on DELO adhesives for overhead stowage bins made of composite materials.

New developments in the aviation industry generally focus on making aircraft safer, more comfortable and increasingly more efficient, while reducing their weight and impact on the environment.

Twenty years ago, only 2% of an aircraft’s structure was made of composite materials. Today, these materials account for more than 50%. We see metal parts being replaced more frequently by novel composite materials, like CFRP, making adhesive bonding the preferred joining method.

As a pioneer of composite technologies, FACC Operations, an Austrian company, has been a leader in design, development and production of components and systems made of composite materials for the aviation industry. They are second to none in having lightweight composite components installed in a wide variety of aircraft models.

Its range of products include structural components for the fuselage and wings like aerodynamic winglets, panels and covers in the engine area, as well as complete passenger cabins for commercial aircraft, business jets and helicopters.

Producing components for all large aircraft manufacturers, including Boeing, Airbus, Bombardier and others, as well as for all the important engine manufacturers and sub-suppliers, FACC Operations achieved a turnover of €705 million during the 2016/2017 fiscal year. Currently, they employ more than 3,400 people worldwide.

Interiors Plant 2 of FACC Operations located at Austrian town Ort im Innkreis

Convenient and functional

As far as the interior of passenger aircraft is concerned, OEMs demand light weight and longevity of overhead stowage bins, entertainment systems, lavatories and so on. Passengers seek comfort and an attractive design.

FACC’s overhead stowage compartments have been used in the Airbus A380 and the A320 family. The company’s interior division relies on composite materials in the form of honeycomb panels to build these compartments. Aramid fibres, like Nomex or Kevlar, are coated with phenolic resin to make the material light and robust. A transparent, decorative film of polyvinyl fluoride is then applied to the surfaces. This decorative film not only makes the compartments dirt-repellent and chemical-resistant, but also is pleasant to the touch and provides an attractive appearance.

The composite sandwich panels are lightweight, offer high torsion resistance, and are completely flat as semi-finished products. Further machining is required if bent or angled structures are needed. The design and manufacture processes for these components takes place in the FACC Operations Interiors plant, located in the Austrian town of Ort im Innkreis.

Using ‘ditch & pot’ technology, the honeycomb structure is cut from the back of the composite sandwich panel. This allows the panel to be easily bent or angled at that point. The resulting cavity is then filled with adhesive. Once cured, the adhesive will permanently keep the sandwich panel in the desired shape.

Given that the products of FACC Operations are used in aircraft, the company requires a high performance from the adhesives they employ. Since the panels they are manufacturing are used in luggage storage compartments a high strength is required from the adhesive. Considering the amount of adhesive that is needed to build its products, they preferred a two-component type with a mixing ratio of 1:1 to simplify production.

Because of the manual production process, and any necessary finishing work on the component, the processing time of a 100g batch of adhesive should be at least 30 minutes, while curing time until initial strength at room temperature should not exceed five hours.

After intensive testing, FACC Operations opted for the new DELO-DUOPOX AB8390. Specially designed and developed by DELO for ditch & pot applications on sandwich panels in aircraft interiors, this versatile construction adhesive is also suitable for bonding of load-bearing joints with inserts.

The adhesive’s double chamber cartridge dispensing system allows the thixotropic epoxy resin to be quickly and easily applied - just like a one-component adhesive. It fully cures at room temperature within the given parameters. Curing can be significantly accelerated by increasing the temperature to +60°C, allowing production cycle times to be reduced without affecting the final strength.

Fibre composite sandwich panel from FACC Operations/Illustration of a Ditch & Pot application, adhesive in light blue colour

Putting safety first

DELO-DUOPOX AB8390 fulfils the requirements as a standalone product set forth by the national aviation authorities, including fire protection in aircraft interiors that’s guaranteed by the flame smoke toxicity (FST) test. The adhesive also complies with RoHS Directive 2015/863/EU.

This flame-retardant adhesive offers good strength and high chemical resistance at temperatures ranging from -55°C to +85°C, which is ideal for aircraft. The tensile shear strength of two sand-blasted, bonded standard samples made of aluminium is 25MPa. This value is almost reached even after 500 hours of storage at +70°C in a reference fluid for Skydrol (tri-n-butylphosphate).

DELO-DUOPOX AB8390 is extremely colourfast, keeping its white colour even after 1,000 hours of storage at +70°C and in air humidity of 85%. FACC Operations can rely on consistent colours to maintain the appearance of their aircraft components, like those used for luggage storage compartments.

www.delo-adhesives.com

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