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interior that also incorporates recycled materials and other composites made with natural fber reinforcements. Exterior body panels, hood and fenders are made with what BMW terms an "unreinforced" thermoplastic. Te rear-hinged passenger doors on the i3 (called "coach doors" by BMW) eliminate the need for a center pillar in the Life Module and give the car a more open feel, despite its relatively small size. A SUSTAINABLE SUPPLY CHAIN To realize the Life Module, BMW launched what has since become the largest and most complex composites material and fabrication supply chain ever established for a production automobile. It verti- cally integrates every aspect of the Life Module's journey, from the spinning of the polyacrylonitrile (PAN) fber precursor and fber carbonization to the conversion of fbers to fabric and fabrication of the carbon fber structures themselves. In just fve years, the i3 has become the frst series-production consumer vehicle in the world to make extensive use of carbon com- posites in primary structural components. And long before the frst i3 rolled into an auto dealer showroom in late 2013, the project had driven a growing group of other auto OEMs to embark on similar paths — a sign that BMW might be the frst to successfully complete the journey but won't be the last to attempt it (see "Learn More"). CT was ofered a chance in March 2014 to visit BMW Group's i3 manufacturing and assembly facility in Leipzig, Germany. Tat visit was the genesis of the following frsthand account of the materials and processes BMW engineers used to make this car and the chal- lenges they met and overcame. MOLDING LIFE INTO THE LIFE MODULE Te manufacture of every carbon fber part produced for the i3 actually begins far away, in Otake, Japan, where a joint venture of Mitsubishi Rayon Co. Ltd. (Otake) and carbon fber maker SGL Group (Wiesbaden, Germany), called MRC SGL Precursor Co. Ltd. (MSP), produces the PAN precursor required for the manufacture of the carbon fber used in the car. Te precursor is delivered to another joint venture, this one be- tween BMW and SGL, called SGL Automotive Carbon Fibers (SGL ACF). Based in Moses Lake, Wash., to take advantage of relatively inexpensive hydroelectric power there, the SGL ACF facility is dedi- cated exclusively to supplying BMW, and it produces 50K tow on two production lines with a total nameplate capacity of 3,000-met- ric tonnes/6.613 million lb (see "Learn More," p. 47). Te facility was designed with expansion in mind and, indeed, demand for the i3, coupled with BMW's plans for carbon fber use in other vehicles, has prompted BMW and SGL to triple the plant's production. From Moses Lake, carbon fber roving is sent to a second SGL ACF manufacturing facility in Wackersdorf, Germany. Here, the fber is converted into a variety of fabric forms, including unidirec- tional tapes and multiaxial weaves (±45°/90°). Tese are cut, kitted and stacked in preparation for resin transfer molding (RTM). RTM'd parts for the i3 Life Module are actually produced at two BMW facilities in Germany: Leipzig and Landshut (northwest of Munich). BMW Leipzig, which opened in 2005, is the principal i3 manufacturing hub. It RTMs all part numbers for the i3 and also houses assembly operations for the Life Modules and subsequent integration of Life Modules and Drive Modules. Te Landshut plant provides supplementary production of certain components, using identical processes and equipment. Located just northwest of the city in an open, sprawling in- dustrial park, the Liepzig campus hosts 10 buildings and is BMW Leipzig comprises 10 buildings, a test track, and four wind turbines that supply part of its electric power. In four of the 10 buildings, 100 i3s roll out per day. Visitors and employees at the Leipzig site's three-story reception/ administration center (lower right) get a striking reminder of the plant's core purpose in an overhead stream of semifnished BMW bodies-in-white. Source (both photos) | BMW AG C T J U N E 2 0 1 4 2 5 0614CT IM-OK.indd 25 5/20/2014 8:32:14 AM