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Afer all side frame hardware is mounted, robots begin the task of integrating the side frames with the foor assembly and other structures. Tis is done exclusively with BETAFORCE, a polyure- thane-based adhesive supplied by Dow Automotive (Auburn Hills, Mich. and Schwalbach, Germany) that is applied in the robot- equipped cells. Brüggemann said each Life Module consumes 160 linear m/525 linear f of adhesive, and added that BMW spent considerable R&D; time determining how much adhesive to apply and where to ap- ply it, to achieve the necessary bond strength. Tis involved careful measurement of adhesive bead height and width and how this cor- relates to the height and width of a compressed adhesive bead. In the end, says Brüggemann, BMW sought a compressed adhesive bead width of 20 mm/0.8 inch at a height of 1.5 mm/0.06 inch and learned that an applied bead width of 8 to 9 mm (0.3 to 0.35 inch) met that requirement. Te goal, then, is to have each adhesive-ap- plication robot meet that bead width specifcation. It takes three to four hours for BMW to assemble each Life Mod- ule. To speed adhesive curing on some parts, attending robots fea- ture a series of small heat lamps on their end-efectors, which gen- erate localized heat at the bond line. Dow says BETAFORCE cure time is about one minute, but that heating of the type BMW applies can shorten that time signifcantly. To veri- fy bond integrity, says Brüggemann, BMW relies on ultrasonic scanning and, occa- sionally, dismantles a fnished Life Module to assess bond strength and fdelity. "We are at 99.7 percent quality," Brüggemann claims, but adds, "we are always chasing higher quality." Brüggemann, who has experience in other BMW assembly plants, also says that the i3 Life Module Body Shop is "less com- plex than a steel body shop. Lighter weight makes product handling much simpler." PUTTING IT ALL TOGETHER Finished Life Modules leave the Body Shop ready for integration with the rest of the i3 vehicle. Tis is done in a third facility on the Leipzig campus where Life Modules and Drive Modules fnally meet on one of two i3 assembly lines. Tere, automated carriages transport i3s from station to station along the assembly line. Assembly starts with the Drive Module, which arrives with batteries, motor and wheels intact on an aluminum frame. Be- fore the Life Module joins the Drive Mod- ule, BMW adds the carbon fber roof, doors, windshield and other glass. Te roof is fab- ricated from a stitched, nonwoven carbon fber fabric supplied by SGL ACF. Notably, the fabric is made from carbon fber scrap material lefover from the i3's weaving and HP-RTM manufacturing processes. Te doors, fenders and hood of the i3 are injection molded from an unreinforced polypropylene/ethylene-propylene-diene monomer (PP/EPDM), a "thermoplastic vulcanizate." Virgin and recyclate grades of the material are used, respectively, for the exterior and interior sections. (For more on i3 body panels, see "Learn More.") Te partially assembled Life Module is then placed atop the Drive Module frame GET AN EXPERT BEHIND EVERY FIXTURE DR. DONALD F. ADAMS, PRESIDENT STANDS BEHIND EVERY FIXTURE WE SELL Call Don today to get expert advice on your test fixture needs! • Over 40 fixtures in stock, ready to be shipped. • Email or call today to discuss your fixture and custom design needs. Combined Loading Compression Test Fixture ASTM D 6641 Short Beam Shear Test Fixture ASTM D 2344 Iosipescu Shear Test Fixture ASTM D 5379 Boeing Modified D 695 Compression Test Fixture Compress Subpress ASTM D 695 2960 E. Millcreek Canyon Road Salt Lake City, UT 84109 Phone (801) 484.5055 Fax (801) 484.6008 email: wtf@wyomingtestfixtures.com www.wyomingtestfixtures.com Dr. Donald F. Adams President 45 years of Composite Testing Experience W T F yoming est ixtures INC. 3 0 C O M P O S I T E S W O R L D . C O M INSIDE MANUFACTURING 0614CT IM-OK.indd 30 5/20/14 10:56 AM