Sunday, May 8, 2011

Camera Sees Through Melting Metal

A new high-speed X-ray video camera, now the fastest in the world, can see through molten metal and watch weld-weakening flaws form in real-time.

With visible light, we could only see the surface of the welding process. You couldn’t see what was happening inside,” said Felix Abt, one of the camera’s designers at the University of Stuttgart. “The only way to see pores that weaken weld seams was to cut the metal into pieces

Automotive companies use robots equipped with high-powered lasers to seam cars together with extreme speed and precision. As laser welding continues to get “more powerful, move faster, go deeper” and increase in use, Abt says, it’s increasingly important to understand the dynamics involved.

To capture the welding process in action, About and his colleague Rudolph Weber use an industrial-strength 4-kilowatt laser, which is roughly 400,000 times more powerful than a DVD drive’s beam. As their laser pummels a hunk of metal moving on a track, a tube fires X-rays through the weld and toward a high-speed video camera.The new X-ray footage isn’t pretty, Abt says, but in a few months he and Weber will tune the camera to increase its clarity. They also plan to imbue welding samples with tracer materials, such as tungsten carbide, that absorb X-rays and improve image contrast.

his is really only the beginning, but we now have the ability to watch processes that lead to porosity in real time while we’re welding


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