Media-Tight Welding of Die Cast Aluminum Parts
The Fraunhofer IWS developed Remoweld Flex, a laser welding process that can weld components made of die cast aluminum in a media-tight manner.
In addition to the Fraunhofer Institute for Material and Beam Technology IWS, Maschinenfabrik Arnold from Ravensburg was also involved in the development of the Remoweld Flex technology. The new process is ideal wherever materials that are difficult to weld are involved and components previously had to be sealed by conventional means - and in some cases manually. An example is the production of electric cars. In these vehicles, batteries and other electrical control units must be cooled. However, the electrical system must not come into contact with the cooling water, otherwise short circuits will occur. This is why control units are often protected by housings made of lightweight die cast aluminum. Following assembly, they are encapsulated by screwed-on covers and plastic seals. Although this is cumbersome, it has hardly been possible to solve it in any other way so far. Die cast aluminum could previously not be welded reliably enough to be watertight. The reason for this is gas-filled cavities in die cast aluminum. If a classical laser cuts these cavities, the effect resembles an abruptly opened balloon: The enclosed gas suddenly escapes from the cavity and simultaneously ejects the molten metal that the laser has just produced. If the seam cools down in this state, defects remain. Ultimately these small leaks could allow water to penetrate the electrical system.
Fine Laser Beam Swings Rapidly Over the Material
The IWS developers have found a way to weld aluminum castings safely and watertight: In the Remoweld Flex working head, the laser beam with a small beam diameter of only about a tenth of a millimeter swings rapidly over the material. One could think of this as the use of a precision needle instead of a coarse burner, explains Dirk Dittrich. This light needle oscillates several thousand times per second in the weld pool. The ESL2-100 module, a system technology developed at the Fraunhofer IWS to integrate laser scanners directly into the plant control system (PLC), controls the movement precisely and quickly by oscillating along the desired contours. This results in a very even and above all watertight weld seam. This is made possible by a well-coordinated interaction of laser scanners, mirror optics, real-time controls and other system components.
Important Step Towards Industry 4.0
The laser modules can be expanded flexibly. For example, they can be coupled with high-speed cameras to ensure real-time quality control. The system also records numerous sensor data during the welding process, which can provide indications of optimization potential. In this respect, the Remoweld Flex technology is also an important step towards Industry 4.0.
This article was first published by konstruktionspraxis.
Original by Dorothee Quitter / Translation by Alexander Stark
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