Laser beam cladding represents a technology, which allows producing high quality coatings, compared with other thermal coating processes. For example, a good metallic bonding between coating and base material, a fine microstructure and good mechanical properties due to the rapid cooling are only some of the numerous advantages. Moreover, the very low dilution allows obtaining the desired metallurgic properties in a one-layer cladding, for example. Nevertheless the spreading of laser cladding in industrial production is very limited, as on the one side the process efficiency is very low and on the other hand the investment costs are very high compared to the actual benefits.
The flexibility and the effectiveness of laser cladding can be largely improved through free forming (shaping) of the coating. The geometric shape of the coating seam is mainly defined by gravity and the surface tension of the melt. An additional force, as for example Lorentź force, can optimize the geometry in order to improve the process properties. Wide coatings seams, for example, allow a low number of overlapping layers when coating large areas. Slim coatings on the contrary are advantageous when generating 3-dimensional structures. Lorentz forces can be induced when a magnetic field is applied and contemporarily a current flows through the processed area. First investigations with a permanent magnet have already been published and show the success of the strategy, even if the effects are restricted due to the fact, that a part of the current flows in the cold material.
High frequency magnetic fields allow inducing a current flow on the surface due to the skin effect. The current interacts with the magnetic field and generates magnetic forces in the surface layer of the melt pool. These additional forces make it possible to shape the coating geometry to the requirements of the application. This paper will deal with the experimental setup as well as with the optimization of form and geometry of the inductor. Furthermore, the physical background of the technique, the influence of different process conditions will be discussed and confirmed by experimental investigation.