Laser mends minirisses

New laser welding robot works with the highest precision

Laser welding robot © Fraunhofer-Gesellschaft
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If an aircraft turbine is damaged or an injection mold is used to make coffee machines or car taps, it becomes expensive. But that could change soon. Researchers at the Fraunhofer Institute for Material and Beam Technology (IWS) have developed a laser system that quickly and precisely eliminates tiny cracks in the components.

At first glance, coffee machines, car taps and aircraft turbines have nothing in common. And yet she calls Steffen Nowotny from the IWS in the same breath: "The new laser welding robot can repair expensive components such as turbines as well as complex tools, such as inserts for injection molding."

A flexible robot arm directs laser light exactly to the part of the component to be repaired: the crack or the broken corner. The energy of the laser beam makes the surface melt. Point by point, the light beam scans the workpiece to be machined and creates microscopic puddles no larger than a few tenths of a millimeter.

At the same time, a gas stream blows powder onto the surface, which joins the melt. Since the granules are very small - the diameter is in the range of micrometers - they melt completely in the laser beam and combine in a very short time very firmly with the base material.

New plant can work better on surfaces

"The laser process is very flexible and we can use metals such as titanium, nickel or cobalt, hard metals and even ceramics, depending on the component and application, so that cracks in tools can be closed or chipped edges can be added, " explains Nowotny. "We can faithfully reconstruct a few millimeters of material - enough to repair the filigree blades or panes of aircraft turbines damaged by the impact of a bird, for example." display

Laser cladding has been used for several years. With the new system, however, the surfaces can be processed more precisely than before. The Fraunhofer researchers use an innovative beam source, the fiber laser. It can apply material of unprecedented accuracy without straining the component. In this way, metal structures can be produced with a resolution of only 100 microns, which corresponds approximately to the thickness of a hair.

The robotic system for surfacing with the highest precision will be on show at the Euromold 2006 in Frankfurt from November 29 to December 2, 2006.

(idw - Fraunhofer-Gesellschaft, 08.11.2006 - DLO)