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3D Printing and Additive Manufacturing In Brief

Understand what is 3D printing and how it differs from other MFG techniques


The terms 3D printing and additive manufacturing are generally used interchangeably. They refer to a group of new technologies and processes that allow parts, models, and (in some cases) assemblies to be built from nothing.

Additive manufacturing is often best explained by how it differs from other types of production. For example:

  • Metal machining is a common and proven form of manufacturing: you start with a block of metal and cut away all of the parts that are unnecessary. Additive manufacturing, on the other hand, builds up only what is needed.
  • Injection molding requires the creation of a mold (usually machined from a large block of aluminum or steel). Molten plastic is then injected into the mold to form parts. Tooling like that is expensive, but additive manufacturing requires little-to-no upfront setup or tooling costs. Furthermore, it's now possible to 3D print injection mold tooling!

In contrast, 3D printing works by slicing an object into thin layers, sometimes as thin as 16 microns (0.0006in), and building each layer in succession. This unique manner of creating things allows for amazing new design opportunities and geometries and open new opportunities. For instance:

  • Parts can now be made that have incredibly complex internal structures that cut out weight while maintaining structural integrity
  • Many design constraints (like requiring draft and eliminating undercuts) that limit other processes are obsolete
  • Original masters for traditional casting processes can be produced easily and quickly

3D printing is currently a hot topic. It's a rapidly growing field and is expected to dramatically affect the way things are made in the near future. Some experts believe it will help reinvigorate American manufacturing, while others believe it will democratize productions of goods and every house will have its own 3D printer.

Whatever the future holds, below is a brief glossary of terms that will help you navigate the world of additive manufacturing.


Common Acronyms

  • FDM: short for fused deposition modeling (tradmarked by Stratsys) and also known as fused filament fabrication (FFF). See: material extrusion, thermoplastic
  • SLS: short for selective laser sintering. See: powder bed fusion
  • DMLS: short for direct metal laser sintering. See: powder bed fusion
  • SLA: short for stereolithography apparatus. See: vat photopolymerization

Types of additive manufacturing

  • Vat photopolymerization: this process builds parts by using light to selectively cure a vat of photopolymer. Stereolithography is the classic example of this type of process
  • Material jetting: this process builds parts by depositing small droplets of photopolymer (similar to an inkjet printer) which are then cured by exposure to light. See MultiJet and PolyJet use for examples of this process type
  • Binder jetting: this process creates objects by squirting a binding agent into a powdered material. See ColorJet and Metal Printing for examples of this process type
  • Material extrusion: this process creates objects by extruding a thin strand of thermoplastic to build layers. It is often likened to a tube of toothpaste or a syringe. See Fused Deposition Modeling
  • Powder bed fusion: this process melts fine layers of powderized plastic or metal into solid objects using a laser. See Selective Laser Sintering and Direct Metal Laser SIntering
  • Sheet lamination: this process builds parts by cutting sheet of material and binding them together in layers.
  • Directed energy deposition: In this process, parts are built or repaired by using focused thermal energy to fuse materials as they are deposited.

Engineering Terms

  • Thermoplastic: plastic that softens when heated and solidifies when cooled
  • Photopolymer: a liquid plastic that hardens permanently when exposed to light