Additive Manufacturing: Directed Energy Deposition
A type of metal additive manufacturing process, directed energy deposition (DED) uses either powders or wires to create finished parts. Unlike most other AM processes, DED is commonly used to repair components or add additional material, rather than simply create new parts.
Types of directed energy deposition, or other names for the process, include directed metal deposition (DMD), laser metal deposition (LMD), laser-engineered net shaping (LENS), and laser consolidation (LC).
DED uses a deposition head to feed either powder or wire into a laser (or electron) beam that melts the material, thereby building up the surface of the part. Because it is not melting material that has already been laid down (such as in powder bed fusion), DED can build on existing parts. Powders can also be mixed, utilizing different material properties. Using different, compatible materials can increase wear, corrosion, and oxidation resistance, one of the benefits of DED.
Limited in size only by the beam manipulation system, another benefit is that DED can produce relatively large parts, as shown in the top right image above: Sciaky (a US 3D printing company) can make 5-meter-large parts in a variety of different materials. Because of the method of deposition, there is also little to no waste involved. However, DED is also a relatively slow process, which takes much longer than other methods to produce parts.
Credit:claudia gabriela marques vieira. Studland Bay, Dorset.
An endangered species of seahorse is under threat from a proposal to drill for oil off the Dorset coast. The species achieved protection in 2008 under the Wildlife and Countryside Act 1981, however in 2017 only 14 spin and short snouted seahorses were recorded around Studland Bay.
A proposal to drill an exploratory well 6km off the Dorset Coast, near Studland Bay, has been submitted by Corallian Energy to the UK Government. A decision is expected by 19 February. The proposal has angered environmentalists and conservationists who fear exploratory drilling could permanently damage the ecosystem.
The Seahorse Trust believes drilling in the area would disturb the seahorses’ environment. Director Neil Garrick-Maidment commented, ‘The latest seahorse sighting was just half a mile from where they are planning to drill, another was seen just under a mile in another direction and a third was two miles away from it.
‘Studland Bay has to become a Marine Conservation Zone because of the environmental impact the anchoring has caused and now we have the threat of an oil spill on the doorstep.’
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