innovations CASTING
Overcoming Challenges in a 30-Year-Old HVAC Duct
W
hen General Dynamics Land Systems, Ster- ling Heights, Mich., needed to
update the heating, ventilation and air conditioning (HVAC) system on the Abrams M1A1 tank, it faced a few ob- stacles. General Dynamics approached Barron Industries, Oxford, Mich., with the potential project, but the invest- ment casting fi rm decided to no-quote. T e 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. T e next problem: General Dynam-
ics had an example of the part and its blueprint from 1983, but no model. Previously an aluminum fabrication, the duct helps cool electronics on the Abrams tank. T anks to ongoing rede- signs of surrounding components, the duct faced restrictive spatial require- ments 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. “The information we received
The component helps cool electronics in the Abrams M1A1 tank, which is used by both the U.S. Marine Corps and U.S. Army.
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 inspec- tion personnel. That put everybody on the same page.” After generating a model from
the nearly 30-year-old blueprints and part, Barron engineers received minor changes from the customer, including
the relocation of an outlet to accom- modate additional changes in the vehicle’s design. Production began on the 13.39-in. x 8.27-in. x 4.33-in. duct, with special attention focused on the tapered “necked down” section of the 1.25-lb. casting, which presented the biggest challenge. “It’s such a long, narrow passage
way, in order to apply the ceramic coat- ing and stucco sand, the articulations within the robot program required some modifi cations,” Barron said. “It required some part-specifi c process engineering.” T e ceramic removal also proved
challenging. Engineers developed a special nozzle for the water jet blasting operation to ensure the thin-walled duct remained fully intact. Castings were pressure tested, and wall thickness was verifi ed via radiography. “Because of its placement within
the already crowded engine compart- ment, this is not an easy part to install and remove,” Barron said. “When we deliver it to [General Dynamics], we believe that they will never have to touch it again after installation.”
The duct’s thin walls in the tapered section of the 1.25-lb. casting presented a number of challenges.
48 | METAL CASTING DESIGN & PURCHASING | Sept/Oct 2013
For more information, go to www.
barron-industries.com.com.
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