Additive Manufacturing Defined

Nov 16, 2012

ASTM International F42 is the Committee on Additive Manufacturing and the Technical Committee (TC) 261 is the ISO counterpart. Recently, ASTM F42 and ISO TC 261 completed an unprecedented agreement. Each standards body signed a Partner Standards Developing Organization (PSDO) for Additive Manufacturing. The PSDO is an effort “to eliminate duplication of effort while maximizing resource allocation within the additive manufacturing industry” (ASTM News 2011). While the agreement has been in place for only a year now, there have already been some recent deliverables to show for the agreement efforts. Most notably is in agreement of additive terminology.

Most product developers, manufacturing enterprises and average consumers know of the term rapid prototyping and might have been aware of the increased media use of the term 3D printing. As more of the traditional rapid prototyping techniques have matured (in both materials and processes), there is a drive from the additive industry to better differentiate the available processes to raise awareness of rapid technologies’ manufacturing value. Communication was paramount in the awareness effort and clarity was the enabler.

This month I would like to provide those process categories with definitions to help enable more accurate discussions between the additive community and potential customers or end-users of the additive technologies.

The most important first step of classification is to discern what is “additive” in general, then the definitions are better equipped to clarify the available processes within “additive.” By ASTM’s terminology, additive is: a process of joining materials to make objects from 3D model data, usually layer upon layer, as opposed to subtractive manufacturing methodologies. Synonyms: additive fabrication, additive processes, additive techniques, additive layer manufacturing, layer manufacturing, and freeform fabrication.

Now that there is a starting point, the definitions (by process) are presented alphabetically below:

Binder Jetting, n—an additive manufacturing process in which a liquid bonding agent is selectively deposited to join powder materials.

Directed Energy Deposition, n—an additive manufacturing process in which focused thermal energy is used to fuse materials by melting as they are being deposited. DISCUSSION—“Focused thermal energy” means that an energy source (e.g., laser, electron beam, or plasma arc) is focused to melt the materials being deposited.

Material Extrusion, n—an additive manufacturing process in which material is selectively dispensed through a nozzle.

Material Jetting, n—an additive manufacturing process in which droplets of build material are selectively deposited. DISCUSSION—Example materials include photopolymer and wax.

Powder Bed Fusion, n—an additive manufacturing process in which thermal energy selectively fuses regions of a powder bed.

Sheet Lamination, n—an additive manufacturing process in which sheets of material are bonded to form an object.

Vat Photopolymerization, n—an additive manufacturing process in which liquid photopolymer in a vat is selectively cured by light-activated polymerization.

If you have any questions/comments about these additive definitions, please contact me via e-mail (

I am Tim Shinbara, Technical Director at AMT. I will continue to follow the technology developments and potential applications found from IMTS as we move toward IMTS 2014!