ProtoCAM: Additive Manufacturing, 3D Printing and Rapid Prototyping.

How the Additive Manufacturing Process Works

AskProtomanAdditive manufacturing is a form of prototyping or production that functions by adding materials to build a form (think rolling a snowman), rather than subtracting materials (think ice carving). Even the most common form of additive manufacturing, 3D printing, essentially just stacks 2D layers in the same way motion pictures are actually a series of stills.

All additive manufacturing technologies share this same basic functionality – and no matter the technology, all projects begin with a CAD file that is digitally sliced into layers as thin as 0.0006 inches. From there, the actual process of layering or building can be accomplished in a number of different ways:

Stereolithography (SLA)

  1. SLA LayersA metal plate is submerged just below the surface of a vat of photo-sensitive polymer resin.
  2. An ultraviolet laser traces the CAD pattern onto the surface. Wherever the laser hits, the uppermost layer of the resin hardens.
  3. The metal plate is lowered incrementally after each layer so it, again, sits just below the surface of the liquid – and the next layer is built on top of the previous, creating the part from the bottom up.

Selective Laser Sintering (SLS) and Direct Metal Laser Sintering (DMLS)

  1. SLSSLS and DMLS are similar to SLA, but rather than liquid resin, the base material is a powdered material (such as nylon, metals and elastomers) that has been rolled onto a surface.
  2. The granular material is fused together (or “sintered”) with the heat from an infrared laser beam.
  3. A roller deposits thin powder layers on top of the previously sintered piece, and laser sintering continues until a 3D piece based on a CAD model is produced.

PolyJet 3D Printing

  1. PolyJetImagine how an inkjet printer works: spraying droplets of ink onto paper in a particular pattern. PolyJet 3D printing is similar.
  2. In PolyJet 3D printing (and all industrial 3D printing), droplets of liquid photopolymer are jetted from various nozzles onto a build tray following the CAD pattern.
  3. The liquid resin is instantly cured by UV light, allowing the nozzles to spray the next layer directly onto the previous one.

Fused Deposition Modeling (FDM)

  1. FDMIn FDM, melted plastic filaments are extruded through a nozzle (think of how a hot glue gun works) onto a support structure based on CAD cross sections.
  2. As each thermoplastic material layer dries, the base is lowered so the next layer can be applied directly onto the previous one.
  3. The support structure is removed by hand once the part or prototype comes off the machine.

Urethane and Metal Castings

  1. Casting is primarily used for rapidly creating small-run copies of existing prototypes or parts.
  2. A mold or “cast” is created with a cavity in the shape of the final part.
  3. Various materials can then be injected into the mold’s void. Once the material hardens, the mold is removed, leaving only the finished piece.

Which technology a customer chooses is determined by what final attributes are most important to a project. Read last month’s Ask ProtoMAN for details on how to determine which technology is best suited for a particular project.

Still not sure what additive manufacturing technique is right for you? Our engineers would be happy to chat about your project. Click here to get in touch today.