Reverse Engineering a 30-Year-Old HVAC Duct
Heights, Mich., needed to update the heating, ventilation and air condition- ing (HVAC) system on the Abrams M1A1 tank, it faced a few obstacles. General Dynamics approached Barron Industries, Oxford, Mich., with the potential project, but the investment casting firm decided to no-quote. Te part’s complexity and relatively small order—only a few dozen would be needed annually—led Barron to assume it couldn’t be competitive price-wise. But General Dynamics, which has worked with Barron since the 1980s, encouraged the engineers to take a second look, and they were awarded the bid. Te next problem: General
W
Dynamics had an example of the part and its blueprint from 1983, but no model. Previously an aluminum fabri-
hen General Dynamics Land Systems, Sterling
cation, the duct helps cool electronics on the Abrams tank. Tanks to ongo- ing redesigns of surrounding compo- nents, the duct faced restrictive spatial requirements and multiple attachment points, which made investment casting the logical choice for production. “We had to reverse engineer it,” said
Bruce Barron, president and CEO. “Te information we received was minimal, so we generated our own 3-D model data imported from our coordinate-measuring machine. Really, once we could generate a 3-D file, we had something that could be utilized by the toolmaker, process engineer, machinist and final inspection
The duct’s thin walls in the tapered section of the 1.25-lb. casting presented a number of challenges.
42 | MODERN CASTING August 2015
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