Benteler-SGL, a joint venture of Benteler Automobiltechnik GmbH and carbon fibre supplier SGL Group, is aiming to produce several hundred thousand of the leaf springs annually.
The polyurethane matrix resin used is Loctite MAX 2 from Henkel, which worked with Benteler-SGL to develop the resin transfer moulding (RTM) process for the leaf spring. Because of its low viscosity, the polyurethane resin rapidly fills the mould and quickly impregnates the fibre reinforcement, resulting in short injection times. With the curing rate also substantially faster than that of epoxy resins, cycle times are shorter overall. Selected additives also make the curing process faster and more flexible.