The terms 3-D 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 directly from computer-aided design (CAD) or building information modeling (BIM) data.

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

This is done by slicing an object into thin strips — sometimes as thin as 8 microns (0.0003 in) — and building each layer in succession. This unique manner of creating things allows for amazing new designs and geometries and opens 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
  • Additively manufactured parts can be post-processed with traditional processes to improve functionality or aesthetics
  • Original masters for traditional casting processes can be produced easily and quickly

3-D 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 think it will help reinvigorate American manufacturing, while others believe it will democratize productions of goods and that every house will have its own 3-D 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 and thermoplastic
  • SLS: short for selective laser sintering, typically in plastic. See: powder bed fusion
  • DMLS: short for direct metal laser sintering. See: powder bed fusion
  • SLA: short for stereolithography apparatus. See: vat photopolymerization
  • HSS: short for high-speed sintering of heat-sensitive carbon black ink. See: powder bed fusion
  • SLM: short for selective laser melting. See: powder bed fusion
  • BAAM: short for big area additive manufacturing, refers to large-scale machines used in construction or manufacturing to produce large prints.
  • EBM: short for electron beam melting. See: powder bed fusion

Types of additive manufacturing

  • Vat photopolymerization: builds parts by using light to selectively cure a vat of photopolymer.
  • Material jetting: builds parts by depositing small droplets of photopolymer (similar to an inkjet printer), which are then cured by exposure to light.
  • Binder jetting: creates objects by squirting a binding agent into a powderized material.
  • Material extrusion: creates objects by extruding a thin strand of thermoplastic to build layers. It is often likened to a tube of toothpaste or a syringe.
  • Powder bed fusion: melts fine layers of powderized plastic or metal into solid objects using a laser.
  • Sheet lamination: builds parts by trimming sheet of material and binding them together in layers.
  • Directed energy deposition: 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