Laser metal Deposition refers to a welding process where a material is introduced into a meltpool, created by a high power laser. LMD falls into the range of Directed Energy Deposition (DED) processes. Typically the filler material introduced is a powder, injected through a conical ring nozzle around the laser beam. The added material creates a weld bead, which then coats the underlying metal. The process is used in cladding applications, where the wear resistance of components is increased, in repair applications where material is added to worn components, or in freeform manufacturing of complicated geometries (3D Printing). Compared to other types of welding LMD results in a smaller heat affected zone, low dilution and low residual stresses in the components.
Additec’s Wire LMD process works in much the same way, however instead of having one laser beam that enters through the center of the deposition head, we use multiple fiber coupled diode laser sources that are distributed evenly around central axis of the head. This frees up the central path for solid filler material, and allows for the unidirectional processing of common mig welding wires. Around the wire orifice our deposition head also features a conical powder nozzle. This way, no functionality is lost compared to conventional laser cladding heads.
When using powder is better:
While we strongly favor running wire prints, powder is still be more suiteable for some applications:
When adding material to a highly irregular surface, where a precise nozzle to part distance is not available as can happen when coating or repairing certain parts, powder will be a better choice.
Also while many alloys are available as wire, some of the more exotic materials may only be available in powdered form.
Annother reason for keeping and supporting powder deposition functionality on our deposition head digital alloying, where two or more materials are mixed in different ratios throughout the deposition process. An interesting middle ground is also the digital alloying of powder and wire at the same time, which is at this point only possible on our deposition system.
More is Less:
Splitting up the laser sources and optics into multiple discrete units reduces the stress on the optical system to a minimum and results in long lifetimes of the optical components. The clean process also contributes to that. All optics are shielded with positive pressure argon and replacements are easy to aquire either through Additec or common optical vendors. Supply information is included in the product manual.