2. Directed Energy
Deposition
• DED is an AM process in which
focused thermal energy is used
to fuse materials by melting as
they are being deposited.
3. Evolution of AM
Ciraud PA (1972) Process and Device for the Manufacture of any Objects Desired from any Meltable Material, FRG Disclosure Publication: 2663777.
• Precursors
Fig. Embodiment of additive manufacturing dated 1972. Metal powder (2) delivery into an
energy source/s (7/7a) to create a part (15) built from a baseplate
Pierre Ciraud’s Invention: 1971
• Concept of Directed Energy Deposition
• Method for manufacturing articles of
any geometry by applying powdered
material
• A Laser, Electron Beam or Plasma
Beam then heats the particles locally
4. Directed Energy Deposition
Figure 1. Resolution vs Part size for different metal AM processes. Based on the figure by DigitalAlloys
https://www.ramlab.com/resources/ded-101/#processes
5. Materials Used and their Delivery Systems
• Materials Used
• Ceramics and Polymers.
• Typically metallics, either wire or powder feed form
• Fe, Ti, Al
• Inconel, Monel, Ti-6-4, Stainless Steels
• Energy sources
• Laser
• Electron beam
• Plasma or Electric arc
• Hybrid - Arc and Laser.
6. The most common DED processes
https://www.ramlab.com/resources/ded-101/#processes
7. LASER METAL DEPOSITION (LMD)
https://www.trumpf.com/en_IN/solutions/applications/additive-manufacturing/laser-metal-deposition/
8. How does it work - Laser Powder BD
• Inert carrier gas •
• Powder size – 20 - 50 μm
• Laser Power – 1 - 36 kW
• Layer – Thickness 0.25 - 0.5 mm
• Width 0.1 - 5 mm
9. How does it work - Laser Powder BD
• Working distance - laser energy density is high enough to form a melt
pool.
• The powder is melted just as it enters the pool not during flight
11. Electron Beam AM (EBAM)
• An electron beam is used instead of a laser, in a vacuum chamber.
• Uses wire or powder feed.
• High speed electron stream bombards the material feed.
• Kinetic energy, turns into heat upon impact, causing fusion
12. How does it work - EBAM
• No bead creation, direct melting of
material.
• 60 KeV KE of Emitted Electrons
• Power concentration – 1kW - 10
MW/mm^2
• Powder size – 45 - 100 μm
• Beam Current Range – 1 - 50 mA
• Layer thickness – 0.07 - 0.15 mm
13. Electron Beam Additive Manufacturing (EBAM)
Process
https://additivemanufacturing.com/2015/10/14/electron-beam-additive-manufacturing-ebam-advantages-of-
wire-am-vs-powder-am/
17. Advantages of WAAM
• Large size
• Additional design freedom
• Low start-up cost
• Wide material availability
• Mechanical Property
https://www.ramlab.com/resources/waam-101/
18. WAAM for repair of metal parts
• Another application of WAAM is the repair metal parts that are
subject to wear in service, such as rails, rotors and dies. The task of
repairing these manually is a tedious, labour-intensive chore that can
be automated with the right amount of monitoring and control.
https://www.ramlab.com/resources/waam-101/
20. Where, When and why DED
• Any metal that can be welded can be 3D printed with DED
• Non-vertical material deposition is possible.
• Build substrate can be a empty flat plate or an existing part onto
which additional geometry will be added
21. Where, When and why DED
• Creating complex shapes
• Cannot be manufactured by other
techniques.
• Adding features to simple shapes
• Complex structures which would
otherwise have a high “buy to-fly”
ratio.
• “Rib-on-plates”
23. Post processing
• The first step is support removal or removal of the part from the
substrate.
• The next and most important step is Heat Treatment.
• – to relieve residual stresses - Annealing
• – to produce desired microstructure - Ageing or Solution Treatment
• The final step is finishing operations
25. Size of structures and design constraints
• Ability to produce small scale features. (overall bad for DED)
– Better in Beam Deposition
– Worse in WAAM / WLAM
• Constraint on part size in WAAM / WLAM
– Large scale parts can be realized using WAAM
– limited in EBAM because of vacuum chamber requirements
26. Wire V/s Powder
• Greater variety and availability of Wire V/s Powder.
• Wire is cheaper than powder.
• Wire is safer than powder and is easier to handle.
• Powder allows for greater resolution and more complex structures.
27. Advantages - summary
• High Deposition Rate
• Dense and strong part
• Multi material range
• Larger parts
• In situ alloying
• Easy material change
31. Friction stir processing
• Friction stirring is a method
of extrusion or plastically
deformation of the material
before it’s melting
temperature by generating
heat due to friction
32. Friction stir additive manufacturing
• FSAM adopted two ways;
• Stacked base FSAM and
• Powder base additive friction stir deposition (AFSD)
In 1971 the Frenchman Pierre Ciraud filed a patent application describing a method for manufacturing articles of any geometry by applying powdered material, e.g. metal powder, onto a substrate and solidifying it by means of a beam of energy, e.g. a laser beam. To produce an object, small particles are applied to a matrix by gravity, magnetostatics, electrostatics,
or positioned by a nozzle located near the matrix. A Laser, Electron Beam or Plasma Beam then heats the particles locally. As a consequence of this heating, the particles adhere to each other to form a continuous layer
DED of metals allows additive manufacturing of large scale metallic components at a much higher deposition rate compared to other AM technologies, such as Powder Bed Fusion (PBF). In general components manufactured with a DED process are characterized by a large part size and relatively low resolution/part complexity when comparing them with PBF. A schematic classification of the AM process according to resolution and part size is proposed in Figure 1.
In conventional laser metal deposition, the laser beam heats up the workpiece locally, creating a weld pool. Fine metal powder is sprayed directly into the weld pool from a nozzle in the processing optics. This fine metal powder melts there and combines with the base material. A layer of approx. 0.2 to 1 millimeter thickness remains. In this way, beads form that are welded to one another, which then form structures on existing base bodies or entire components. If required, many layers can be built up one on top of the other. Laser metal deposition can create high build or volume rates of multiple cm³/min on 3D surfaces, with feed rates of 500 mm/min and as high as multiple meters/minute. To apply lines, areas, and shapes, the automatically controlled processing optics move over the workpiece. An intelligent sensor system ensures that the layer thickness is even everywhere at all times.
Wire Arc Additive Manufacturing (WAAM) is a production process used to 3D print or repair metal parts. It belongs to the Direct Energy Deposition (DED) family of Additive Manufacturing processes. WAAM is executed by depositing layers of metal on top of each other, until a desired 3d shape is created. It is a combination of two production processes: Gas Metal Arc Welding (GMAW) and additive manufacturing. GMAW is a welding process used for joining metal parts using an electric arc, and additive manufacturing is the industrial term for 3D printing. The production of parts using WAAM is carried out by a welding robot integrated with a power source. A welding torch attached to the robot is used to melt the wire feedstock to build 3D parts.
Wire Arc Additive Manufacturing (WAAM) is a production process used to 3D print or repair metal parts. It belongs to the Direct Energy Deposition (DED) family of Additive Manufacturing processes. WAAM is executed by depositing layers of metal on top of each other, until a desired 3d shape is created. It is a combination of two production processes: Gas Metal Arc Welding (GMAW) and additive manufacturing. GMAW is a welding process used for joining metal parts using an electric arc, and additive manufacturing is the industrial term for 3D printing. The production of parts using WAAM is carried out by a welding robot integrated with a power source. A welding torch attached to the robot is used to melt the wire feedstock to build 3D parts.
Wire Arc Additive Manufacturing (WAAM) is a production process used to 3D print or repair metal parts. It belongs to the Direct Energy Deposition (DED) family of Additive Manufacturing processes. WAAM is executed by depositing layers of metal on top of each other, until a desired 3d shape is created. It is a combination of two production processes: Gas Metal Arc Welding (GMAW) and additive manufacturing. GMAW is a welding process used for joining metal parts using an electric arc, and additive manufacturing is the industrial term for 3D printing. The production of parts using WAAM is carried out by a welding robot integrated with a power source. A welding torch attached to the robot is used to melt the wire feedstock to build 3D parts.
Large size The maximum printable size primarily depends on the reach of the welding robot that is used. WAAM offers the capability of manufacturing parts with dimensions over a cubic meter. The maximum printable dimensions can be increased by using robot tracks and welding manipulators.
Additional design freedom WAAM and other additive manufacturing methods allow for the manufacturing of relatively complex shapes. This also means that topological optimization and the production of generative designed parts become more accessible.
Low start-up cost Compared to other DED systems like direct metal laser sintering or electron beam additive manufacturing, WAAM offers a relatively lower cost. Additionally, WAAM offers a higher deposition rate compared to other AM techniques, which also contributes to the cost effectiveness of the process.
Wide material availability WAAM uses a consumable wire as its feedstock. Depending on the application, a multitude of alloys are available in wire form. This offers a wide range of materials and mechanical properties to design and manufacture a part.
Hybrid manufacturing WAAM can be used in combination with other production methods, to add specific features to traditionally manufactured parts.
Combined materials WAAM offers the possibility of designing functionally graded components, where multiple materials can be combined to design a part, for e.g cobalt alloy Stellite 6 and ferroalloy AISI 316L.
Waste reduction Material is only deposited where needed, which can potentially lead to a waste reduction of 50%. This is especially relevant for parts that conventionally are milled out of solid blocks and/or parts that are made out of costly materials, for example titanium. Topological optimization can maximize efficiency in the use of materials.
Mechanical properties WAAM can outperform the mechanical properties of conventional manufacturing processes like casting and forging. Learn more about the mechanical properties of WAAM parts in the materials library.
The main advantages of a WAAM process over the other AM technologies are:
high production rate up to 5 kg/h;
Large build volume (>1x1x1 m) ;
mechanical properties outperform casted and compete with forged material;
low cost of the wire feedstock;
Friction stirring is a method of extrusion or plastically deformation of the material before it’s melting temperature by generating heat due to friction
In stacked type FSAM, the metal plates ot layer are joined one by one. The length of the tool pin is taken longer than the built layer to ensure the joining of two stacked layer at a time. The schematic arrangement of the stacked type FSAM technique and step by step bonding of layers are shown in Fig. 7
In this method, a tool attached with pin and shoulder inserted into the top surface of the overlap sheets which moves forward, resulting in the sheets bonding due to frictional heat and severe plastic deformation. Due to the movement of the tool, a joint is developed by the movement of material from the front of the pin to the back of the pin. As a result, the multilayered sheets are bonded together like a sandwich structure. The thickness of the final product depends upon the thickness of the individual layer, and the number of operations by which sheets/plates are bonded
The mechanism of AFSD is different to stacked type FSAM. The schematic diagram of AFSD is shown in Fig. 8. It consist of a hollow cylindrical tool shoulder (without tool pin) to deliver the feed material like powder or solid rod diretly to the stirring zone. The rapid rotation of the tool shoulder generates the friction heat at the interface of tool shoulder and substrate plate (base plate). Due to the frictional heat, the feed material is heated and softened and plastically deforemed which bonds to the substrate plate at the interface [115]. The continuous bonding of plastically deformed feed material to the substrate plate make the deposition of an addition layer of desired thickness. Subsequently the addition of layers one by one makes a 3D object.
