Laser Metal Deposition (LMD) 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.
Wire Deposition Process
Finished Part after Machining
Wire Deposition through Central Nozzle
Close-up picture of the Nozzle
Powder Deposition through Conical Nozzle
Additec’s Wire LMD-WP (Wire Powder) 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. In addition, it is also possible to deposit wire and powder at the same time to create a new alloy of the two components.
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.
Laser metal deposition lends itself to a range of applications:
Near net shape manufactuing
Using the process to additively generate complex parts from the ground up. Also known as metal 3D printing or free form fabrication. This way of producing parts affords a high level of design freedom, and eliminates complex CNC programming or time consuming casting. Futher it is even possible to blend different materials / alloys within a single component using multiple Additec material feeders.
Coating exisisting components with a protective layer. Our process is well suited for it, due to low dilution of the base metal, allowing thinner coats to effectively protect the base metal. Cladding processes are commonly used in the Oil and Gas industry, but are increasingly adopted by other industries as well.
Feature Addition / Hybrid manufacturing
When integrated into a milling machine or manufacturing process chain, our deposition process can be used to add features to components that would otherwise require unfavorably large stock or be difficult to cast as single piece.
Replacing high value components completely can be costly and inefficient. Laser metal deposition introduces a way to reliably rebuild worn areas of components with minimal distortion.