Engineers ‘grow’ prototype with 3-D printer

Published Oct. 16, 2015
By John Parker
Staff Writer

TINKER AIR FORCE BASE, Okla. -- A customer's recent request for Tinker Air Force Base's REACT Office to make a prototype of an aluminum aircraft part was a routine one for the four engineers who work there.

The out-of-the-ordinary aspect was the way they accomplished the job.

Engineers with the base's KC-135 Stratotanker System Program Office noticed that two aluminum seal retainers of different types that were part of an engine fan reverser weren't the right height when they were installed.

To fix the problem, engineers made some drawing changes on the parts' 3-D computer models, including a dimension change on one of the seal retainers. The next step was to make a prototype to see if the issue was solved.

The REACT engineers, part of the 76th Commodities Maintenance Group, loaded the computer model and fired up a ProJet 860Pro 3-D printer to make an exact replica of the revamped seal retainer in gypsum - the same material in home and office drywall.
Inkjet print heads dispensed a binder formula on to four-thousandths-of-an-inch thick layers of gypsum powder. Starting from nothing, each layer of powder supports the one above it and supports the part while it "grows." The printer, which looks similar to a large office copier, took about 13 hours to make the part.

The finished prototype was a hardened-gypsum copy of the part. Its raw material didn't matter because the engineers only needed to find out if the computer models were correct and the parts fit as designed, which they did on the first try. If it hadn't, new prototypes could have been made just as quickly and cheaply.

If the prototyping had used traditional manufacturing techniques, REACT engineer Mark Lucash said, "they would have to send that design to a local manufacturer, who'd get a block of aluminum, get the programmers to program that part, figure out the (machining) tool paths, get it on their schedule and then get it machined until, maybe in six months, if they didn't have too many priorities, they could have that part to test it."

Engineer Todd Bayles added, "You may save thousands or tens of thousands of dollars compared to machining a chunk of metal."

Created in June 2014, the REACT Office in Bldg. 9001 is tasked with both exploring applications for 3-D printing, also called additive manufacturing, and putting it into action. The office includes mechanical engineer Jason Mann and materials science engineer Lt. Aaron Washburn.

The Oklahoma City Air Logistics Center is currently finalizing a strategic plan to make additive manufacturing a major tool in Tinker's industrial future. Other engineering groups at Tinker share additive manufacturing ideas and new breakthroughs through the Tinker Additive Manufacturing Users Group, which includes the 76th Software Maintenance Group, the 76th Propulsion Maintenance Group and others. Engineers currently use more than a dozen 3-D printers on base.

The REACT Office's recent work includes printing small parts that are expected to become approved spares for aircraft, including a cosmetic cockpit panel and an E-3 AWACS sun visor bracket. The long-term vision is to 3-D print essential aircraft parts such as fuel nozzles and fan blades.

"We know parts are going to be manufactured this way eventually," REACT engineer Nate Pitcovich said. "So we're trying to increase our knowledge and experience with the various technologies so that we're prepared when it comes to that. We need to have the knowledge base and the equipment available when that day arrives."