BMW 7 Series Plant: Dingolfing, Germany
Via four different manufacturing methods, CFRP goes mainstream in automated multi-material BIW and assembly operations at BMW’s busiest plant.
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BMW AG’s (Munich, Germany) largest manufacturing site in Europe — in area (2.8 million m2) and volume (360,000 cars in 2015) — is situated in Dingolfing, Germany. More than 17,000 employees — 12,000 in the plant and another 5,000 in surrounding support facilities — turn out 1,600 cars per day. Dingolfing not only produces 15 models, including all variations, of BMW’s 5, 6 and 7 Series, but also one model each of the 3 and 4 Series. It also turns out components for BMW’s electric vehicles and, as the company’s Center of Competence for aluminum, it builds car bodies for Rolls-Royce (Manchester, UK) as well.
“We’ve learned how to handle complexity,” emphasizes Plant Dingolfing managing director Josef Kerscher. “We are the only automotive manufacturing facility worldwide to handle not only this many different models, but also engines from three to 12 cylinders, as well as plug-in hybrids.”
The Dingolfing complex began as the Hans Glas GmbH auto factory, which BMW acquired in 1967. Since 1973, BMW has produced almost 10 million vehicles there. Over the past three years, Dingolfing has undergone an upgrade valued at more than a half billion euros for the new 7 Series production alone, including increased automation and aluminum die casting along with a new carbon fiber-reinforced plastic (CFRP) production hall and a new state-of-the-art facility to produce the first body-in-white (BIW) combining steel, aluminum and CFRP, known as the Carbon Core.
The multi-material BIW is a big reason why the 7 Series is breaking new ground in top-of-the-line vehicle performance and luxury (for more on the latter, see Learn More located under Editor's Picks on the top right). The BMW 7 Series is 130 kg lighter than its predecessor and its principal competitor, the S-class Mercedes. Although only 3% of the BIW parts are CFRP, totaling 13 kg, they account for 40 kg of weight savings. It contributes to what BMW calls Efficient Dynamics, which reduces fuel consumption and emissions while enhancing the driver experience. “I get 100 km from 4.5 liters of gas,” says Kerscher. “This is what you would expect from a very small car, not from a luxury sedan. The key to this is lightweight construction.”
The BMW 7 Series is now in full production. “The launch was very successful,” says 7 Series product manager Christian Metzger, “achieving cost, quality and volume targets.” The launch was
the culmination of a three-year program that included not only product development, but also a three-year process in the plant to develop all of the required manufacturing processes. The latter was CW’s focus as it toured Dingolfing’s 1.6 million-m2 Plant 2.4.
CFRP: 4,000 parts per day
Sixteen CFRP parts make up the Carbon Core, each manufactured using one of four technologies (Fig. 1 and see Table 1 below), with each chosen to meet specific part shape and property requirements, yet minimize weight. Michael Ahlers, BMW head of Process Chain Body-In-White and Exterior, points out the Carbon Core parts on a 7 Series BIW displayed at the entrance to the plant’s 11,000m2 CFRP production/logistics area. Noting the B-pillar (Fig. 2), Ahlers explains, “It uses CF prepreg covered with a film of epoxy adhesive. Both are hardened to the formed steel B-pillar in one press step.” High-pressure resin transfer molding (HP-RTM) is used in the roof rail, made in the nearby BMW Landshut plant, to meet roof pressure test requirements, while wet compression molding (or wet pressing, see Learn More) enables cost-effective, short-duration cycle times for parts such as the tunnel, sills and selected roof bows (Fig. 3).