NSWC Crane Scanning Process to Save Millions
Navy NewsStand
Story Number: NNS080726-01
Release Date: 7/26/2008 8:08:00 AM
By Naval Sea Systems Command Office of Corporate Communications
Crane, Ind. (NNS) -- Engineers and scientists from NAVSEA's Surface Warfare Center Crane (NSWC Crane), recently developed a non-invasive scanning process that is expected to save millions of dollars for the Missile Defense Agency (MDA).
The scanning process is for inspecting critical fire control and missile components for MDA's Ground-Based Midcourse Defense Program (GMD).
NSWC Crane scientists created a computed axial tomography (CT) X-ray scan process that can identify various types of foreign object debris (FOD) inside ground safeing device (GSD) arm/disarm switch (A/D) switches without having to physically open the switch.
This investigative inspection technique guarantees switches are free from FOD before being put inside the missile. As missiles are being built to populate silos, finding these problems before missile emplacement ensures the missile in the silo will not need to be removed for repair.
The increased reliability in the switch is expected to save the government several million dollars in inspection and removal costs.
FOD can consist of wire clippings, insulation, solder balls, cloth ties, epoxy, adhesives or any other small material that can contaminate or make a switch malfunction. NSWC Crane's work in detecting this failure without damaging the GSD A/D switches is important because maintaining an increased reliability of our nation's ground-based interceptors is critical in protecting our country.
John Mietus, of NSWC Crane's Strategic Missions Center, explained that since there was no initial information available on the GSD A/D switch, he and fellow engineer Matt Kay reverse-engineered the switch to determine the root cause for failure.
"Matt assembled a switch, placing various types and sizes of FOD in it."
Using a XYLON CT X-ray machine, they validated that CT-scan was a viable means to non-destructively screen the switches for FOD. Mietus explained that there are three main aspects to the CT-scanning process: data acquisition, data rendering, and analysis.
"The data acquisition process consists of taking multiple scans at regular intervals over a volume (region) of interest," said Mietus. "Each scan corresponds to a single slice of the volume of interest. Once all the scans have been taken, they are stacked to form the volume."
He likens this to individual playing cards, or a slice in his case, that collectively build a whole deck, known in his world as a volume of interest. This stacking of the slices is the data-rendering portion of the process.
"After the data is rendered, the analysis is conducted by visually inspecting the volume as a solid 3-D model or as a 2-D cross section," said Mietus. "All the image information for the switch and casing is in the software."
He added that when the casing information is subtracted from the data, FOD information from inside the switch is readily viewed.
Mietus and Kay documented their results and have continued to refine the process. Their work provided a detailed knowledge of switches and spawned a new pre-screening process being implemented by the manufacturer during production. The cost for implementing the CT X-ray inspection process to examine an existing switch is about $700 to $1,200 per switch. Mietus said that the time and money saved by not having to perform the expensive evolution of pulling missiles from the silos to replace switches that fail is extensive.
The cost of the switch itself is $32,000 so maintaining the high integrity of the switch during manufacturing is also important to the program.
NSWC Crane's Strategic Missions Center is dedicated to developing, deploying and sustaining the technology that ensures that weapons systems are fully reliable and always available to warfighters.
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