Directed Energy Deposition
Directed Energy Deposition (DED) comprises of Additive Manufacturing techniques in which material is added to an existing component or surface. By utilizing a power source with high energy flux density, such as a laser or plasma arc, feedstock material in the form of either powder or wire is melted and fused. Through a relative motion between the processing tool and the surface, the molten material is solidified into beads which are deposited layer upon layer forming the 3D shape. When used with metals, the DED process is usually referred to as direct metal deposition or metal deposition for short.
- Fully dense parts
- 100% material utilization
- Simpler and safer material handling
- Lower feedstock cost
- Very high deposition rates
- Superior surface roughness
- Flexible deposition setup
- Lower maintenance
Powders need to be handled with care. Some metal powders are to be considered explosive if mixed with air and the fine powder particles are hazardous to both people and the environment. Because of this, handling of powders is associated with extra effort, cost and time when compared to wire. Wires are not considered to constitute a health risk and are not explosive nor a fire hazard in air.
Wires are also, when handled with appropriate gloves, not easily contaminated unlike powders. Wire can also be transferred to the processing point without the use of carrier gas.
Due to the ability to feed current through the wire, preheating of the feedstock can be used to add extra energy and thereby allowing for higher deposition rates. This approach can increase the effective energy for melting material without the need for a more powerful primary power source such as a laser or electrical arc. In order to transfer a lot of material to the processing spot for very high deposition rates, one can either use wires with larger dimensions or use several wires in a parallel configuration.
The wire is self-supporting and rigid as opposed to powders. This has the benefit that wire can be fed into the processing point independently of gravitation. This is an important trait when it comes to adding features on existing components with limited access and reorientation possibilities to suit the deposition process. A powder/gas stream in powder-DED on the other hand, can be operated only when close to parallel to the gravitational vector.
Just like powder-DED, wire-DED is capable of coaxial wire feeding making the system flexible in respect to the deposition pattern.
The use of wire as feedstock material benefits from the existing wire delivery systems developed for welding. These are more durable and cheaper to purchase and maintain than their powder counterparts.
To fully exploit the benefits of wire-fed DED it is essential that consistent material properties can be ensured throughout the printed part, repeatedly. This is in fact one of the main challenges with all AM techniques today. At Procada we are therefore specialized in automation and closed-loop process control of metal-wire DED. Our solutions ensure that key process variables are maintained within a qualified process window at all times, resulting in printed parts with highest material integrity. Additionally, our closed-loop control systems support arbitrary deposition patterns including all wire feeding directions. This unique ability of our control systems means that the DED process can now be optimized for each part or feature to be printed. Printing speed does not longer come at the sacrifice of part resolution.