Directed Energy Deposition
In the case of directed energy deposition (DED), powder or metal wire is used with an energy source to add material or to fuse a material onto an existing part or to create a new part. Here are the three types of energy-directed deposition:
- • Laser DED: Laser DED deposits powder on the material while the beam is melting at the same time. This process can produce much faster build-up speeds than traditional laser powder bed fusion.
- • Arc DED: An EWI specialty that is more dynamic than any other additive manufacturing process. Arc DED is suitable for large constructions. The advantage for manufacturers is that there are existing arc-welding robots and power supply systems.
- • Electron Beam DED: EB-DED allows incredibly quick production of large parts, which gives it an advantage over other additive manufacturing types. The process is used in heavy machinery, manufacturing, mining, and aerospace industries to produce large, low-volume components.
Binder jetting additive manufacturing uses an ink-jet printing head to print a binder on a powder that “binds” the metal particles together in a green state. The parts are then extracted from the powder bed and must undergo a de-binding and sintering process (in the oven) to make the parts completely dense and rough. Parts usually shrink by 20-25% during sintering.
This type of additive manufacturing connects the sheets of material to form part of it. There are two types of sheet lamination additive production:
- • Ultrasonic Additive Manufacturing: This type of sheet lamination uses ultrasonic vibrations to weld metal tapes together until it is capable of forming objects.
- • Friction Stir Welding: Using friction stir welding improves the properties of the material when each layer is stirred. This creates diffusion and reduces the size of the grain for a secure bond.
Filament or thermoplastic material is used for the production of parts in material extrusion. The filament (or thermoplastic) is heated in this process, and then layered continuously through the nozzle to produce the final product or component. New items are available inside the plastic “rods” which are extruded with metal filler. The parts then move through the process of de-binding and sintering to produce metal bits, like binder jetting.
In this additive manufacturing process, new materials are available that have a metal filler inside the plastic rods which are extruded. The parts then move through the debinding and sintering process, like binder jetting, to create metal pieces.
In contrast to other types of additive manufacturing, vat photopolymerization uses liquid resin. This photopolymer resin is applied layer by layer, and then the UV light hardens the resin to make the final part or object.
Designing for 3D Printing
All parts produced using a 3D printer must be designed using some kind of CAD software. This type of production depends mainly on the quality of the design of the CAD and also on the precision of the printer. There are several types of CAD software available, some of which are free, others require you to purchase the software or have a membership or subscription. Selecting what kind of CAD software is perfect for you will depend on what you are designing. However, any of the free CAD software packages will do for beginners who simply want to learn CAD and create basic shapes and features.
The following points must be kept in mind when designing a part to be printed in 3D:
- • The part needs to be a solid part, that is, not just a surface; it needs to have a real volume.
- • The production of very small or delicate features may not be properly printed, depending on the type of 3D printer that will be used.
- • Supports will be required for parts with overhanging features to be properly printed. This should be taken into account as the help needs to be removed after the model has been cleaned. This may not be an issue unless the part is very delicate, because it might break.
- • Be sure to calibrate the 3D printer before using it; it is essential to ensure that the part is properly attached to the built-in plate. If it isn’t, the component may be lost at some point and the whole print job may be destroyed.
- • Some thought should be given to the orientation of the component, since some printers are more accurate on the X and Y axes than the Z-axis (Figures 8.1 to 8.3).