Direct Energy Deposition
Process description
Direct Energy Deposition (DED) combines welding with other technologies to produce parts through additive manufacturing. In this process, a high power heat source is used to melt and deposit a feed stock directly onto a plate (typically welding it onto a sacrificial print bed). Each layer is welded onto the last until the part is fully formed. The part must then be cut from the build plate, and post processed, usually through subtractive manufacturing such as milling, to produce a finished product.
DED also has the unique ability to modify existing metal parts. By treating the old part as the print surface, it can build out new layers, similar to printing on a traditional build plate.
Strengths & Weaknesses
The benefits of Direct Energy Deposition:
- Industrial scaling: DED machines are often much larger then other print types, enabling the production of fairly large parts.
- Part modification: DED has the ability to add additional features onto weldable metal parts, allowing for the combination of different manufacturing technologies or repair of broken parts.
The drawbacks of Direct Energy Deposition:
- Surface finish: Although the exact surface finish is dependent on the feed stocked, DED has very poor surface finish in general.
- High energy: The constant melting of metal in the process uses very high amounts of energy.
- Post processing: DED prints often need to be machined to fix geometries and surface finishes.
Machine Property Ranges
| Low | High | |
|---|---|---|
| volume X/Y/Z (mm) | 200/200/200 | 5080/2794/2794 |
| resolution (mm) | 1 | .67 |
| layer height (um) | 800 |
Categories of DED
the two primary factors that effect the deposition of DED printers is going to come from the kind of feed stock, and the variety of heat source used the way that material is supplied to the heat source
Feed type
- wire fed: Wire feeding will give a consistent flow of material to the deposition pool. This means that little material is wasted, but since the amount of material being deposited limits the complexity of parts available. this limited geometry also means that the surface finish is greatly affected.
- powder fed: when using powder methods not all material being deposited ends up being used. this means that the size of the deposition is variable allowing for complex geometries, but a recycling system must be used
energy sources
- laser: laser based ded systems allow for precise control over the hear source. when paired with powder feeding its best used when more complex geometries are needed.
- plasma: due to the development of arc welding technology this tends to be the most energy efficient form of DED. normally paired with wiring feeding. it is best suited for large scale manufacturing.
- electron beam: this is one of the less common heat sources for DED systems. it is very fast, and because it must be done in a vacuum contamination is limited.
Technologies
- WAAM: wire arc additive manufacturing is the generic term for the combination of a plasma energy source and a wire feedstock
- PL: Powder laser is the generic term for a combination
- LENS: created by Optomec Laser engineered net shaping is a proprietary combination of a laser power source and a powder feeding system
- EBAM: created by Sciaky electron beam additive is a propriety combination of a electron beam energy source, and a wire feedstock
- RPD: Created by Norsk titanium rapid plasma deposition is an advanced version of WAAM