One-minute curing time

Lightweight construction methods are now a permanent feature of automotive engineering, but the mass production of composite components can present challenges

Tailored adhesives, together with fast-curing and reliable resins, are essential to the viability and cost efficiency of these highly automated, short production cycles and Henkel has, for some years, been at the forefront of this technology.

A typical example of these latest developments is Henkel’s LOCTITE MAX 2 composite matrix resin for resin transfer moulding (RTM) processes. This polyurethane-based product is extremely fast curing, ensuring more economic processes and improved throughput. In addition, the quality of the resin enhances the quality of the end-product, says Henkel.

LOCTITE MAX 2 is a two-part product that has been specifically developed for RTM with glass or carbon fibres. “Because of its low viscosity, the polyurethane matrix resin rapidly fills the mould and quickly, yet gently, impregnates the fibre material, resulting in short injection times. With the curing rate also substantially faster than that of epoxy resins, cycle times are shorter. A post cure can also be performed to ensure a full cure in around one hour at 150°C,” advises Henkel.

Historically, there have been limitations in the use of lightweight components in relation to cycle times and level of automation. In particular, composite components were very rarely used for visible vehicle parts, as the requisite post-treatment of the surface for subsequent painting has been too costly and time-consuming.

“Developments such as LOCTITE MAX 2 are therefore significant contributors, not just to the quality and performance of the vehicle, but its economical production as well,” adds Henkel. “Indeed, a German tier 1 supplier and manufacturer has already benefited from this technology. This polyurethane matrix resin has enabled automotive specialist Benteler-SGL to develop an innovative, glass-fibre-reinforced leaf spring with a projected production output of over 100,000 parts per year.”

The leaf spring has now been adopted by Volvo on the XC90, its premier crossover SUV, and enables a weight saving of 4.5kg per axle. Based on the SPA architecture platform, this leaf spring concept is also featuring on the Volvo S90 and V90 models.