The jet engine was a technological wonder of the 20th century. In the 21st, college students can make one with a printer.
This spring, engineering professor David Sheffler’s class built a one-quarter-size replica of a Rolls-Royce jet engine with a 3D printer that fabricated parts from plastic. The printer created parts accurate to 100th of an inch, nearly the level of precision necessary for a real jet engine. A full-size Rolls-Royce AE3007 turbofan jet engine costs approximately two million dollars. The replica? Only $1,500 for plastic and another $300 for metal bearings, nuts and bolts.
Of course, the engine won’t be used to fly anywhere. Firing the jet engine would melt its plastic parts into a blazing puddle. Also, it doesn’t produce the 8,000 pounds of thrust that its titanium and nickel-cobalt counterpart does. But, using compressed air rather than jet fuel, the replica runs at the same idle speed as a real engine. “We put a strobe light up to it, and the core was spinning 1,500 to 2,000 rpm,” Sheffler told Popular Mechanics.
A 3D printer fabricates a three-dimensional object by printing a series of cross-sectional slices layer by layer. It can print objects made of many materials with different mechanical and physical properties in a single process. To make the parts of the replica engine, Sheffler’s students refined the computer-aided design files—which contained information about those cross-sectional slices. Then the class spent more than 150 hours assembling the printed pieces.
“This class gave students a real hands-on experience in manufacturing and machining parts of a working machine that incorporates principles from their other engineering courses,” says Sheffler. “With this process they were able to see and touch parts that looked just like the real thing. Without the introduction of these 3D printers, this type of experience is simply not possible.”
UVA engineering classes won’t start competing with Rolls-Royce to make engines for the U.S. Air Force’s Unmanned Aerial Vehicles. But now they know firsthand how a jet engine works and how to use a 3D printer—for which the possibilities are practically endless.