ONSERT technology

Combining bonding and mechanical fastening

Design optimized specifically for aviation requirements

ONSERT technology combines adhesive strength and mechanical fastening in a single process. Transparent plastic components are applied directly to the component using the light-curing adhesive—without the need for drilling. After light-curing, functional elements such as cable holders can be easily clipped on.

DELO PHOTOBOND FB4151 is a modified UV- and light-curing adhesive that has been specially developed for use in aircraft interiors. It cures completely within 8 seconds and achieves a strength of around 20 MPa on various plastics and metals typically used in aviation, while also offering high flexibility with around 80 percent elongation at break.

Advantages of bonding for lightweight structures

Screw and rivet connections have long been standard in aviation, but they reach their limits with modern lightweight materials. They weaken the material through drilling and increase the weight through additional fastening parts. The aviation industry benefits from the ONSERT process because it does not require drilling and is therefore gentle on the material.

Conventional joining methods weaken lightweight materials through drilling, while the adhesive solution preserves the integrity of the material. Adhesives have a decisive physical advantage. They distribute stresses over a larger area and thus have a stress-equalizing effect. This is a critical factor in sensitive lightweight construction materials, as it prevents stress concentrations. In contrast, conventional mechanical connections such as screw connections or rivet connections create localized stresses around the drill holes.

This is particularly critical in lightweight structures made of carbon fiber composites or thin aluminum sheets. Screw connections and riveted joints create localized stress concentrations around the drill holes—weak points that can act as crack initiation points and result in expensive repairs. The uniform force transmission of adhesives fully exploits the material properties and prevents premature fatigue cracks—which reduces maintenance costs in the long term. The ONSERT process is also suitable for various substrates and offers design freedom in the positioning of fasteners.

Application in aircraft interiors

Aircraft interior applications are subject to special safety criteria. DELO PHOTOBOND FB4151 complies with the flame retardancy and smoke requirements of FAR Part 25 § 25.853 (a)(1)(i) Amdt. 15/Amdt. 25-116 and ABD0031. In addition, the material has low outgassing, is solvent-free and complies with Directive 2015/863/EU (RoHS). The recommended operating temperature range of the adhesive extends from −40 °C to +120 °C. These properties qualify the adhesive for fastening applications in aircraft interiors.

Series production and automatability

The eight-second curing time makes the technology interesting for industrial applications. The automatability of the process enables integration into existing production lines and reduces production costs. Precise dispensing and reproducible curing enable consistent quality in high volumes. Unlike screw connections, which must be set individually, multiple ONSERT elements can be processed in parallel.

The technology has already demonstrated its potential in initial aircraft seat development projects, such as the fastening of cable guides in Recaro business class seats. Further applications in cabin interiors and other lightweight structures are currently in the qualification phase.

Böllhoff will present the fastening solution at the Aircraft Interiors Expo in Hamburg, which will take place from April 14 to 16, 2026. The company can be found there at booth 6C125.