Application Technology

To meet the high-quality standards laid down by HELLA GmbH & Co KGaA, a manufacturer of lighting systems, for the bonding and sealing of headlamps and rear lights in passenger cars, WEVO-CHEMIE GmbH has developed products that facilitate both freedom in design and efficient production.

The headlamps and rear lights of passenger cars and commercial vehicles are not only important design elements but, as components of assistance systems, also fulfil increasingly complex functions. To ensure that electrical and electronic components are reliably protected from environmental influences throughout their entire life cycle, the components must be well sealed.

The adhesives used play a key role in this – they must meet the requirements for durability and resistance, but must not be visible, especially in the headlamps’ field of vision. The increasing use of large and complex components also poses a challenge in production.

To meet the technical and aesthetic requirements, HELLA is using potting and adhesive systems from WEVO – including specially adapted variants of the polyurethane-based WEVOPUR 801. This results in a number of positive options compared to conventional systems.

For instance, complex geometries of LED and matrix headlamp systems can be realised by adjusting the reactivity and flow properties of the adhesive systems. WEVOPUR 801 is used close to the headlamps’ visible area or ‘field of vision’ – this demands the perfect combination of low viscosity during application with fast setting and good wetting for downstream processing. The specific circumstances of the design and structure of the headlamps need to be taken into account, while still guaranteeing high process quality with regard to application, adhesion and further processing. On the other hand, cable runs and electronic components at the rear of the headlamps and rear lights are potted. In this case, the system used must above all offer sufficient flowability to prevent bubbles and other inclusions from forming. In addition, modified thixotropies ensure the adhesive does not flow through cavities into the interior of the headlamp.

In both of these cases, the subsequent tightness of the seal plays an important role, because the electrical and electronic components must be reliably protected against environmental influences. The moisture and gas tightness of the lamp housing is also of ever greater importance, because unlike halogen or xenon headlamps, the illuminants in LED headlamps no longer heat up the headlamp lens; this can lead to condensation or even icing up inside the headlamp if air or moisture is able to ingress the lamp unit. Furthermore, the WEVO solutions have been optimised in terms of thermal conductivity and heat resistance so the heat losses of the illuminants can be dissipated to the lamp housing, ensuring the lamps’ long-term functionality.