Additive Manufacturing with powder and light
LMD (Laser Metal Deposition), often also referred to as DED (Direct Energy Deposition), laser cladding or laser deposition welding, is a proven technology for producing high-quality layers and structures from metallic materials. The process uses fine metal powders that can be transported in a precisely dosed amount with a carrier gas. This powder / gas mixture is directed onto the surface of a workpiece using special nozzles. A high-energy laser beam is also focused on the same place, so that the metal powder melts. The resulting melt pool can now be guided over the workpiece surface and solidifies almost instantly. In this way, metal layers or complete three-dimensional structures can be created line by line. Since argon is used as the carrier gas and an additional protective gas shields the weld pool, any influence from ambient oxygen is avoided.
Since structures can be built up with this method, it is referred to as Additive Manufacturing (AM). This makes the fundamental difference to conventional (subtractive) manufacturing clear: the latter begins with a valuable block of metal, from which everything is removed that is not part of the component that is to be manufactured. Put simply, these conventional processes produce an extremely large amount of waste just to make one workpiece. Additive manufacturing is completely different: it brings exactly the material that is needed to exactly the place where it belongs. And this with impressive efficiency, since almost all of the powder used is converted into usable metal, and since the desired geometries can be produced with only a few tenths of a millimeter oversize. LUNOVU machine systems use LMD technology in a unique, intelligent machine environment and thus provide the tools to revolutionize industrial production. Coatings can be applied to complex 3D components, worn workpieces can be repaired or complex three-dimensional components can be created out of “nothing” – a resource-saving and sustainable technology that often enables previously unthinkable applications.
In addition to LMD, there are other additive manufacturing technologies and processes. Many of them have already found areas of application. However, the LMD process has a number of impressive advantages over other technologies:
- Low heat input into the base material
- Low degree of mixing
- High material utilization of up to 90% of the powder used
- Near net shape processes
- Precise controllability
- Possibility to produce material mixtures / gradients
LUNOVU uses a specially developed technology in its LMD systems, which allows three-dimensional surfaces to be optically captured. The paths that the nozzle must move is then automatically calculated in order to achieve the desired additive structure. This extends the possibilities of the LUNOVU – LMD:
- Application of coatings on arbitrary 3D surfaces
- Repair and modification of components that are not documented by CAD models
- Build of 3D structures on existing 3D components
The LMD process is also characterized by the fact that a large number of materials can be used. In addition to a wide range of steels, the most widely used materials include nickel and cobalt-based alloys, aluminum alloys, titanium alloys and special hard materials based on carbide particles, for example. Furthermore, alloys and mixtures can be produced specifically in the process by precisely dosing different types of powder and mixing them close to the processing nozzle. This way, even components with variable material compositions can be manufactured so that material properties can be set individually for specific component areas. LMD technology is also predestined for new materials and material research. On the one hand through the possibility of producing multi-component materials directly in the LMD system, and on the other hand through modified material properties by controlling the heat input or the cooling rates. In recent research, examples of such materials are, for example, the so-called high entropy alloys, which consist of five or more components with similar atomic proportions.