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27 September 2018 16:40
Metal 3D Printing: What is Direct Energy Deposition?
Direct Energy Deposition (DED) is a series of several similar metal 3D printing technologies that creates parts by melting and fusing material as it is deposited. While it can be used to manufacture new parts, DED is typically used for repairing and rebuilding damaged components. One of the main metal 3D printing technologies, DED is already utilised in key industries like aerospace & defence, oil & gas, as well as the marine industry. In today’s tutorial, we’ll explore the DED process, its benefits and limitations and existing use cases.
How does DED work?
Direct Energy Deposition sometimes goes by several different names, including 3D laser cladding and directed light fabrication. Additionally, certain proprietary technologies modelled on DED are sometimes used interchangeably: Electron Beam Additive Manufacturing (Sciaky), Laser Engineered Net Shaping (Optomec), Rapid Plasma Deposition (Norsk Titanium) or Wire Arc Additive Manufacturing. Although each process works slightly differently, the principle behind them is the same.
In the DED process, the feedstock material, which comes in either metal powder or wire form, is pushed through a feed nozzle where it is melted by a focused heat source (most commonly a laser, but could also be an electron beam or arc) and successively added onto the build platform. Both the heat source and feed nozzle are mounted on a gantry system or robotic arm. The process typically takes place in a hermetically sealed chamber filled with inert gas to better control the material properties and protect the material from unwanted oxidation.
Check out the technology in action:
DED supports a wide range of metals, including:
- Titanium alloys
- Stainless steel
- Maraging steels
- Tool steels
- Aluminium alloys
- Refractory metals (tantalum, tungsten, niobium)
- Superalloys (Inconel, Hastelloy)
- Nickel Copper
- Other speciality materials, composites and functionally graded materials
Notably, the materials used in DED are significantly cheaper than metal powders used in powder-bed metal AM.
Direct Energy Deposition: pros and cons
DED technology has been in use for a number of years now and offers a range of benefits:
- Ideal for repairing parts: The ability to control the grain structure of a part makes DED a good solution for the repair of functional metal parts.
- Larger 3D printed parts: In contrast to powder-bed metal AM processes, which typically produce smaller, high-definition components, some proprietary DED methods can produce larger metal parts – for example, Electron Beam Additive Manufacturing (EBAM) technology, developed by Sciaky, is said to be able to produce parts larger than 6 metres in length.
- High printing speed: Typically, DED machines have high material deposition rates. For example, some DED processes can achieve a speed of up to 11 kg of metal per hour.
- Less material waste: With SLM and DMLS processes, because powder is spread on the build platform and then selectively fused together, this can often leave a lot of unfused powder which has to be reused. In contracts, with DED only the needed amount of material is deposited. Since there is no waste powder to recycle, this results in efficient material usage and cost savings.
- Multi-material capabilities: With DED, powders or wires can be changed or mixed during the building process to create custom alloys. The technology can also be used to create a gradient between two different materials within the same build, achieving stronger material properties for a part.
- High-quality metal parts: DED produces highly dense parts with mechanical properties as good as or better than those of comparable cast or wrought materials. Parts produced with DED can also reach near-net shapes, meaning that they will require little post-processing.
- Hybrid manufacturing capabilities: DED is one of few metal 3D printing technologies apt for integration into machining centres to create a hybrid manufacturing solution. By mounting a deposition nozzle on a multi-axis machining system, highly complex metal parts can be produced faster and with increased flexibility.
What are the limitations of DED?
Some of the limitations of DED include:
- Low resolution: Parts produced with Direct Energy Deposition tend to have low resolution and poor surface finish, thus requiring secondary machining which will add time and cost to the overall process.
- No support structures: DED does not lend itself to creating support structures, which limits the production of parts with certain geometries, for example, overhangs.
- Cost: DED systems are typically very expensive, with costs exceeding $500,000.
Direct Energy Deposition: the machines
In the table below, we’ve summarised the main companies which developed proprietary technologies based on DED process, alongside the available machines and their build volumes.
|Manufacturer||System name||Build volume|
|Sciaky||EBAM® 68||711 x 635 x 1600 mm|
|EBAM® 88||1219 x 89 x 1600 mm|
|EBAM® 110||1778 x 1194 x 1600 mm|
|EBAM®150||2794 x 1575 x 1575 mm|
|EBAM® 300||5791 x 1219 mm x 1219 mm|
|Optomec||LENS 450||100 x 100 x 100 mm|
|LENS MR-7||300 x 300 x 300 mm|
|LENS 850-R||900 x 1500 x 900 mm|
|LENS 860 Hybrid||860 x 600 x 610 mm|
|BeAM||Modulo 250||400 x 250 x 300|
|Modulo 400||650 x 400 x 400|
|Magic 800||1200 x 800 x 800|
|InnsTek||MX-600||450 x 600 x 350 mm|
|MX-1000||1,000 x 800 x 650 mm|
|MX-Grande||4,000 x 1,000 x 1,000 mm|
|DMG Mori (Hybrid)||LASERTEC 65 3D||735 x 650 x 560 mm|
Common use cases
DED has been successfully applied in various industries, including aerospace, oil & gas, defence, marine and architecture. Aerospace manufacturers are increasingly using the technology to produce structural parts for satellites and military aircraft. Lockheed Martin Space, for example, has recently qualified Sciaky’s EBAM process to build titanium fuel tanks domes for satellites. By using the technology, the company was able to reduce production time for the component by 87% and cut lead time from two years to three months.
DED is being considered for structural parts for commercial aircraft as well. One example is recently FAA-approved aircraft titanium parts for Boeing 787 Dreamliner, manufactured by Norsk Titanium. The Norwegian company used its proprietary Rapid Plasma Deposition technology, a form of DED technology, which helped to achieve a considerable improvement in buy-to-fly ratio compared with conventional manufacturing methods. Now, as titanium parts enter series production, Boeing expects to cut its production costs by $2 to $3 million per aeroplane.
In addition to producing metal parts, DED technology is well-suited for repairing damaged parts. Thanks to the strong metallurgical bond and fine, uniform microstructures DED can produce, components like turbine blades and injection moulding tool inserts can be reconditioned. By repairing worn parts, moulds or dies, DED allows significantly reducing downtime and costs associated with part’s replacement whilst extending the life of the part.
Furthermore, DED can be used to modify parts. For example, by using the technology to deposit a wear resistant hard-facing layer, wear and corrosion resistance of a part can be improved.
The future of DED
DED offers numerous advantages for industries that require the creation or efficient repair of high-value equipment and bespoke metal parts, especially those of a larger size. Looking into the future, we expect the scope of applications for the technology to expand, particularly due to the exciting trend of hybrid manufacturing. Through its integration with conventional manufacturing technologies, DED could bring advances to industries on the lookout for innovative and cost-effective production opportunities.