4. Classification of AM Processes

Curing liquid resin with light
Example Methods: SLA, DLP, LCD

Vat Photopolymerization is an additive manufacturing process that involves using light to cure liquid resin into solid objects. The light source, often a projector or laser, selectively cures specific areas of the resin to form layers. This process builds the object layer by layer, starting from the bottom of a vat of liquid resin and moving upwards as each layer is solidified.

Imagine a photographer taking a picture in a dark room. They shine a flashlight onto a canvas covered in special paint that only reacts to light. With each flash, the paint hardens, and by the end of the session, they have a complete, vibrant painting formed layer by layer.

Droplets selectively deposited and cured
Example Methods: PolyJet, MultiJet

Material Jetting is a 3D printing technology that works by depositing tiny droplets of material onto a build platform. These droplets are then cured or solidified, layer by layer, to create the final part. This method allows for high accuracy and the possibility to use multiple materials in a single print, enabling color and material variation.

Think of a printer that shoots droplets of ink onto paper. Just like this printer creates text and images piece by piece, Material Jetting builds 3D objects by layering different materials, crafting intricate designs with color and texture while controlling precisely where each droplet lands.

Binder selectively joins powder material (sand, metal, ceramics)

Binder Jetting is a process that involves selectively applying a binding agent onto a bed of powder material. The binder holds the powder particles together at specific locations, forming a solid shape. Once the printing process is complete, the unbonded powder is removed, leaving behind the finished part, which may require additional processing for strength.

Picture a sandcastle being built at the beach. When you mix water with sand, the sand sticks together more effectively. Similarly, in Binder Jetting, a liquid binder acts like the water, joining powder particles to produce a form that you can later take to a stronger structure.

Thermoplastic filament extruded layer by layer
Example Methods: FDM, FFF

Material Extrusion, such as Fused Deposition Modeling (FDM), is a common 3D printing technique where thermoplastic filament is heated until it melts, and then extruded through a nozzle onto a build platform. The material is deposited layer by layer to create a three-dimensional object. As subsequent layers are added, they fuse with the underlying layer, forming a solid structure.

Think of icing a cake with a piping bag. As you squeeze the bag, the icing comes out in a steady stream, allowing you to create different patterns by moving your hand. In Material Extrusion, the printer 'pipes' out melted plastic, layer by layer, to build up the final object in much the same way.

Laser or electron beam fuses powder in a bed
Example Methods: SLS for polymers, SLM/EBM for metals

Powder Bed Fusion is a technique where a laser or electron beam is used to melt and fuse powder particles together. A layer of powder is spread across a build platform, and the laser or beam selectively targets areas to melt and bond the particles. Once a layer is fused, the platform lowers, and a new layer of powder is applied, repeating the process until the part is complete. This method is especially effective for creating complex geometries.

Imagine baking a cake in multiple layers. At every level, you add a layer of batter before baking it until it's firm. In Powder Bed Fusion, the laser is like the oven, melting each layer of powder into a solid cake gradually, until you have a fully formed part.

Stacking and binding sheets (laminated object manufacturing, paper/metal)

Sheet Lamination involves stacking sheets of material, which can be paper or metal, and bonding them together using adhesives or heat. This process allows for the creation of complex shapes by adding layers in a controlled manner. Once the layers are bonded, they can be cut and shaped to finish the part.

Think of building a book out of individual sheets of paper, where you glue or stitch each sheet together at the spine. Each new page helps build the book, just as in Sheet Lamination, where each new layer creates the final object that can be shaped and designed as needed.

Focused energy melts material as itʼs deposited
Example Methods: DED, laser/arc/wire deposition

Directed Energy Deposition (DED) is a process where focused energy, such as a laser or welding arc, is used to melt material as it is deposited onto a surface. This method allows for the addition of material to existing parts, useful for repair or enhancement applications. DED is capable of using various materials, including metals and ceramics.

Imagine a sculptor using a blowtorch to melt metal and add it to a statue. Each deposit of melted metal fuses with the existing piece, adding new features or repairing areas, similar to how DED allows new material to be fused onto a part.

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