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A D V A N C E D M A T E R I A L S & P R O C E S S E S | J A N U A R Y 2 0 2 1 2 6 JOINING ISSUES The body construction team need- ed to establish a baseline for the more than 2200 self-piercing rivets (SPR) that would join the multiple stamped parts of the body and the box. The joint is a combination of up to four layers of sheet metal of different alloys and gaug- es (stack-up), each of which requires a specific tool setup. In the absence of any CAE program capable of model- ing the insertion of an SPR, each joint schedule had to be developed experi- mentally and then verified and adjusted on the floor during the build. Adding to the complexity was a fixed floor space that restricted the number of stations, and short cycle times that precluded ro- bots from tool switching on the fly. The ideal joint schedules are those that can handle several stack-ups that might be found in a given station. Ford’s P552 platform was comprised of a large number of stack-ups and numerous possible combinations. This resulted in a staggering number of schedules, each requiring statistically representa- tive verification tests. The project was entrusted to the joining team at Ford’s Research & Innovation Center. It would take them six months to plan the proj- ect, obtain funding, and secure new headcount, lab space, and equipment. By the time the lab began operating in third quarter 2011, the X1 prototypes had been built and tested, with ad-hoc joint schedules established on the fly with Henrob Corp., the SPR gun suppli- er. The lab’s first mission was to support theM1 build scheduled for mid-April 2012. For the stamping engineering team, CAE modeling work for X1 had started months earlier. It was an all- out effort by Bill Anglin’s team at Troy Design and Manufacturing Co., under the supervision of Ford’s stamping en- gineering CAE team and Laurent Chap- puis, with technical support fromCedric Xia’s team at the Research & Innovation Center. The tool build was completed by late third quarter 2010, and the cor- relation studies started after the deliv- ery of X1 parts in the fourth quarter. The studies included full 3D scans of select- ed parts, which were then meticulously compared to CAE strain and springback predictions. The thick gauges planned for P552 required new forming lim- it curves that could not be developed using existing laboratory tooling. A new 200-mm limiting dome height tool had to be designed and funded, and was built by Ford’s Dearborn Tool and Die team. Meanwhile, Tesla surprised Detroit by showing a complete body-in-white with closures for its upcoming Model S at the North American Auto Show in January 2011 (Fig. 3). It was an alumi- num-intensive design with extensive use of extrusions and castings. As such, it was more akin to an Audi A8 than the sheet-intensive Jaguar XJ. The pace continued to acceler- ate in 2011, and by April, Ford’s Expedi- tion/Navigator models joined the Super Duty truck on the platform. X1 testing came and went, confirming the gener- al design direction. P552’s high volume precluded castings and its design would include 90% aluminum ABS by weight, a single laminated steel part, and strategically placed extrusions (Fig. 4). PART SOURCING In concert with Ford’s purchasing team, the switch to an all-aluminum body enabled a re-think of the part sourcing strat- egy. In 2011, there were virtually no American stamped parts suppliers with significant aluminum ex- pertise, and it would be Ford’s respon- sibility to bring them the necessary technical support. A side effect of the switch to aluminum was a four-fold in- crease in the value of the work in pro- cess. Tomaximize the value of stamping offal, it made sense to concentrate the external sourcing to a select few sup- pliers, centered around Ford’s historic Rouge Complex in Dearborn, Michigan. The complex included the Dearborn Stamping Plant, Dearborn Frame Plant, and the lead assembly plant for P552, the Dearborn Truck Plant. The final sourcing strategy concen- trated 75% of the parts by weight into Dearborn Stamping Plant, setting it up to become the largest all-aluminum stamping plant in the world. To handle this volume, the plant would be upgrad- ed by adding four new press lines (P3 to P6), one high-speed cut-to-length line Fig. 3 — Tesla Model S at the 2011 North American Auto Show, showing the use of extrusions and castings as well as sheet. Courtesy of L. Chappuis. Fig. 4 — Material selection for the 2015 Ford F-150.