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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 1 9 2 6 aluminum’s behavior during trimming would occupy the best tooling minds at Ford and the aluminum suppliers for more than a decade. With two hoods and a produc- tion rate approaching 300,000 units per year, Ford was now the undisputed leader in aluminum parts production. For the next five years, Ford would ac- count for roughly 90% of the alumi- num ABS on the road in the U.S. If this sounds impressive, the actual numbers were still very modest: Ford’s buy was only about 6000 tons per year, with the parts themselves representing about 3500 tons and 2500 tons leaving the stamping plant as scrap. More sobering yet, aluminum represented only about 1% of the capacity of the stamping plant to which the production was sin- gle sourced. At the time, Ford U.S. oper- ated eight stamping plants. While the high value of aluminum scrap was well understood, the best that could be done in terms of segre- gation was to reverse the conveyor un- derneath the press line. When running an aluminum part, the spur conveyor under the press would direct the pre- cious aluminum scrap into tubs rather than to the central spine conveyor that carried all the steel scrap to the shred- der/compactor. The tubs would then be towed to a collection point and picked up by a scrap dealer to be sold on the secondary aluminum market. The solu- tion was low investment, but labor in- tensive and somewhat hazardous. The basement of a stamping plant is not intended for vehicular traffic, making the trips down narrow aisleways tricky and unpleasant. VEXING TECHNOLOGY ISSUES The level of technology for alumi- num part manufacturing still left much to be desired. For example, welded downstanding flanges not only crippled styling, but increased part weight. Also, the molding hiding the pinch welds at the windshield was both unaesthetic and expensive. The poor productivity revealed by the recent launch added to the urgency to solve the issues that still forced aluminum ABS to be processed differently from steel. While the new al- loys had shown the capacity to mimic steel’s ability for hemming outer skins over inner panels, there was no accept- able solution for actually joining the two parts and ensuring the dimension- al stability of the assembly. Steel parts could be resistance spot welded using specialized tooling that left almost no damage on the visible surface—not so for aluminum. Steel parts could also be adhesively bonded directly after stamping without any special surface preparation or cleaning. Again, not so for aluminum. It was imperative for the next generation of aluminum parts to conform to the steel process. Ford assembled a multidiscipli- nary task force to find a solution. At the kickoff, all the major adhesive sup- pliers acknowledged that none of their existing products could bond alumi- num sheet without surface preparation. The lead researcher from a prestigious aerospace adhesive supplier told the Ford engineers they should prepare to integrate a cleaning system in their pro- cess, much like Volvo had done five years earlier. Spurred on by manage- ment, the team would have none of it. They approached the problem by look- ing at the aluminum sheet, its surface, the stamping lubricants, and the adhe- sives as a system. The first step was a screening of adhesives and lubricants to find the most promising combinations. The team then specified which lubricants could be used as well as the maximum application amounts. Adhesive devel- opment then proceeded against a fixed set of lubricants, using the existing steel performance criteria. After three years and 101 prototypes, the results of their efforts were realized in the 1995 trunk lids of the Grand Marquis and Crown Victoria (Fig. 2.) They sported a uni-alloy 6111 design, adhesively bond- ed hems, and resistance spot welded reinforcements. Assembly took place directly after stamping, without any in- termediate cleaning. The following year saw the launch of the Ford Taurus and Mercury Sable trunk lids (Fig. 3), and the hood for the Ford F-150. RENEWED RECYCLING EFFORTS By the end of 1996, Ford was pro- ducing more than 1.5 million stamped aluminum assemblies per year, using more ABS than all of the other car man- ufacturers combined. Another outcome of the development project was a re- newed focus on recycling the stamp- ing scrap. Chicago Heights Stamping Plant (CHSP) now produced about one million assemblies per year, each Fig. 2 — 1995 Ford Crown Victoria trunk lid. Fig. 3 — (a) 1996 Ford Taurus trunk lid; (b) unpainted Taurus trunk lid; (c) Mercury Sable trunk lid inner. (a) (b) (c)