CompositesWorld
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NEWS 65 CompositesWorld.com BENTELER SGL, Ort im Innkreis in crash testing (Fig. 2). Ascher says the epoxy RTM process is low volume, "but very complex. e issue is managing CTE [coeffi- cient of thermal expansion] in this larger part, so the cure must be a bit longer vs. HP-RTM." e upper and lower pieces are joined with epoxy adhesive. "is was a good project for us from a learning point of view," he explains. "We use these projects to build our expertise." e gallery tour finishes with a CFRP door module in production since 2013, used for the Porsche 911 GT3 and one other model, and a foam-cored CFRP spare wheel well developed as a demonstrator for a high-end OEM (Fig. 3, p. 64). Featuring complex geometry and formed in one shot, using RTM, the part uses foam core to impart stiffness and reduce noise, vibration and harshness (NVH), the latter an added function driving new composites applications in multi-material struc- tures. "e original SMC solution did not provide sufficient NVH," Ascher explains. Leaf spring production As the tour exits the lobby, it proceeds through a door midway along the southern wall of the massive production hall. As he leads the tour through an assortment of CFRP parts being readied for shipment and an array of gluing jigs used to produce parts for Audi, Ascher explains that the building is split between leaf spring production to the left and CFRP production on the right. e former consumes roughly one-third of the hall, comprising automated manufacturing cells for Daimler springs and a much larger production line, which has produced more than 500,000 composite leaf springs per year since 2015, for all Volvo vehicles that are based on the new Scalable Product Architecture (SPA) platform. Standing in front of a production cell, Ascher explains, "e specific leaf spring being produced will change through the day per computer- controlled production management system. Everything is JIT [just in time]." Within the cell, an automated cutting machine, supplied by BENTELER Mechanical Engineering on the left, alter- nates between cutting rolls of unidirec- tional (UD) fabric and NCF. A robotic arm picks and places cut plies into a preforming station at right. A quality assurance (QA) kiosk sits across from the preform station. "If it detects an issue, it automatically fixes it," says Ascher. "For example, if the material orientation or place- ment is not accurate, it will move the material." e tour walks north, passing on the right pits in the floor that are pre-wired and ready for new presses in anticipation of future growth. Turning left, the all-white, self-contained Volvo leaf spring line fills the west end of the building. Currently the world's highest-volume autocomposites production line, it is a massive, industrial cell, arranged linearly from material input at the west, through cutting, preforming and RTM, to rows of machining cells at the east, followed by testing cells. "We bend- test every spring," notes Ascher. Located midway along the Leaf spring lines in the prod- uction hall have turned out more than 500,000 springs for Volvo vehicles alone. FIG. 4 500,000+ leaf springs per year The Volvo leaf spring production line fills the west end of BENTELER SGL's Ort im Innkreis facility, including post-cure oven (bottom left), machining cells (above) and 100% check — including bend test — of every spring before being labeled and readied for delivery (top left).