No noise, no spattering metal, no smell of burning – actually you would imagine welding to be different. But not when it comes to a machine from Steigerwald Strahltechnik. In the large chamber, the interior of which can be seen through a window, only a glistening strip of light glides along its path. In less than a minute, it has circled around the shaft of an aircraft turbine, on which a huge blade wheel is mounted. Then the light disappears and the seam between the shaft and the wheel looks like it did before. But that’s an illusion: What had been loosely connected parts are now permanently connected, welded with an invisible electron beam that has penetrated deep into the metal. Admittedly, welding with a laser does look more spectacular, with the red light beam and spattering molten metal in the welding seam. The electron beam, on the other hand, performs its work unobtrusively, although in fact it welds metal blocks as thick as bricks.
WELDS EVERYTHING THAT TURNS
Looking back: In 1952 Karl-Heinz Steigerwald presented the first processing machine with electron beams for industry. In 1963 he founded Steigerwald Strahltechnik GmbH, now part of Global Beam Technologies AG. For the first time, these machines enable workpieces to be welded deep inside, not just on the surface. Karl-Heinz Steigerwald is one of the pioneers who helped achieve the economic upturn in post-war Germany with brilliant ideas – just like Oskar Lapp, who in 1958 invented the first industrially manufactured control cable with ÖLFLEX®, which is now also integrated into the modern versions of Steigerwald’s machines. The electron beam penetrates 150 millimetres into the metal. The heat input is low, which is important for components that should not warp with heat – which is also why the welding process looks so unspectacular.
Electron beam welding is often the last processing step for a component, as no subsequent processing of the welding seam is required and nothing is deformed. This is why electron beam welding is widely used in the aerospace industry. “Everything that rotates in jet engines is welded using electron beams”, says Marko Wittig. Mostly using machines from Maisach, as the sales manager emphasises. Although only around 15 plants leave the factory every year, Steigerwald Strahltechnik is the global market leader in this small but important niche. The technology is not only in demand in the air, it is also used on the ground. In the automotive industry for the hardening surfaces in camshafts, increasingly in electromobility, where copper parts for electric motors or power contacts are connected. The vacuum chambers for producing microchips are welded using electron beams, as are the hollow chambers made of niobium, with which research institutes such as the CERN in Geneva or DESY in Hamburg accelerate elementary particles to almost the speed of light. The systems can not only weld, but also drill – at tremendous speed. They shoot up to 3000 holes per second into the metal plates used as filters, for example for plastic recycling. Speed is also absolutely necessary: a filter like this can have 40 million holes.
OLDIES FROM THE 1980'S
Given the enormous power of the machines, it is amazing how durable they are. Some customers still operate oldies from the 1980s without major repairs. The electrical connection systems also contribute to this. “I’ve been at the company for 32 years now and still see machines from us that started operation before my time”, says Wolfgang Rudolf, Head of Technology at Steigerwald. This is probably due to the fact that only cables from LAPP are installed – from ÖLFLEX® control cables to UNITRONIC® data cables, connectors and all kinds of accessories. Nobody can say exactly when the collaboration between Steigerwald and LAPP began – perhaps it was in the 1980s. It is well known at Steigerwald, however, that the relationship is fruitful, based on mutual appreciation and that the high quality of LAPP products has been impressive for years. “LAPP’s field service convinced us to rely entirely on its products and we have not regretted it”, says Rudolf. In addition, Steigerwald’s customers, including an increasing number of automotive manufacturers, keep a list of preferred component suppliers that machine manufacturers must comply with. And as the name LAPP appears on many of these lists for cables, it is the most convenient way for mechanical engineers such as Steigerwald to incorporate LAPP everywhere.