Air Force reaps dividends from scanning electron microscope

  • Published
  • By Brandice Armstrong
  • 72nd Air Base Wing Public Affairs
TINKER AIR FORCE BASE, Okla. (AFPN) --  Since receiving the largest-known scanning electron microscope in the world in September 2007, Air Force officials here said the documented savings to date on less than eight components exceeds $70,000. 

Tinker Air Force Base officials project annual savings to the Air Force of up to $1 million, plus the incalculable benefits of mishap avoidance.

Within a 9-foot-by-10-foot-by-12-foot vacuum chamber, the microscope -- Germany's VisiTec Microtechnik GmbH MIRA X -- has a 5-foot-by-5-foot by 5-foot operating volume. It is capable of examining objects 60 inches and larger. Members of the Oklahoma City Air Logistics Center Metallurgical Analysis Laboratory's MIRA X can magnify an object more than 100,000 times and its stage can rotate 360 degrees.

"All the angular manipulations used to view an object are accomplished by moving or rotating the column, so the piece stays still," said Scot Roswurm, a senior materials engineer and acting chief of the 76th Maintenance Support Squadron's Metallurgical Analysis Section. "In addition we have detectors that gather the electron data to provide an image, which are also moveable. So we can look at very complex geometries and even down into some internal cavities and resolve images.

"(The microscope) is an integration of the best elements and components from manufacturers of microscopes from all over the world," Mr. Roswurm said. "In this case, for instance, the column is actually produced by (the Carl Zeiss Corp.), one of the finest optic and imaging companies in the world."

The MIRA X analyzes maintenance wing engine and aircraft components including compressor rotors, damaged fan blades, shafts, spacers and air seals, fan frames, nozzle segments and thermal sprayed parts. Engineers and technicians recently inspected a sheath off of a boom which was 7 feet long with a fracture of nearly the same length.

On average it takes about eight hours to complete a component interrogation, which does not include part cleaning, part set up, chamber pump down or other preliminary procedures. 

The MIRA X provides exciting opportunities, said Russell Howard, the OC-ALC engineering director.

"Not only will it result in significant cost savings and invaluable support to critical aging aircraft issues, but also we look for its advanced and unique capabilities to attract additional workload to Tinker AFB from other government agencies and private industries," Mr. Howard said.

Previously, the lab could only magnify features of a large, intact object 70 to 80 times its original size. Also, prior to the arrival of the MIRA X, lab technicians had to cut parts to approximately 6 inches or less to fit into its largest standard SEM. Propulsion components were often destroyed before final investigative or interrogative results were determined.

"If I can evaluate a large component without cutting it up, I save the time and cost of cutting it," Mr. Roswurm said. "I can also keep the features of interest of components in their proper context, meaning that I don't have to reassemble the pieces after the fact in order recall the position of a crack with respect to its assembly or to accomplish subsequent dimensional analyses."

Conceptualization of the MIRA X at Tinker AFB began more than five years ago when lab engineers brainstormed how a large chamber microscope would benefit the Air Force. Once it was determined that an excellent return on investment was possible, a team of lab, Physical Sciences Flight support section, and Maintenance Support Group officials began researching how to acquire the $3 million microscope and its enclosing facility.

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