Making three-dimensional solid objects from a digital file through 3D printing has been changing engineering, medicine, education, and has even altered the way that toys are created. Additive manufacturing makes use of 3D printing for industrial purposes, by, according to ISO/ASTM 52900:2015 - Additive manufacturing - General principles – Terminology, “joining materials to make parts from 3D model data, usually layer upon layer”.
Standardized practices for additive manufacturing are important to create conformity amongst the different organizations and industries that use the technology. One major issue has been the ambiguity in the terminology. For example, the word additive manufacturing has been historically interchangeable with “additive fabrication, additive processes, additive techniques, additive layer manufacturing, layer manufacturing, solid freeform fabrication and freeform fabrication”; the standard reduces this to its current single usage. In addition to the definitions of the general principles of additive manufacturing covered in ISO/ASTM52900:2015, the terminology for testing of systems used to 3D print in additive manufacturing processes are addressed in ISO/ASTM 52921:2013 - Standard terminology for additive manufacturing - Coordinate systems and test methodologies.
Additive Manufacturing File Format
Additive manufacturing differs from traditional manufacturing since is much less time- and labor-intensive by eliminating the need for tool production. This is possible as the blueprint of the end product that is fully realized in a physical form is saved on a digital file. ISO/ASTM 52915:2016 - Standard specification for additive manufacturing file format (AMF) Version 1.1 sets a format for the CAD (Computer Aided Design) standard file in AMF (additive manufacturing file format) for all additive manufacturing processes that can be used in any industry. This is meant to replace the past STL format standard, which does not attempt to manage the specific colors and textures used in additive manufacturing. This new format is more specific, but still allows for the mass customization and reduced overall cost that is characteristic of the AM process.
Additive Manufacturing Material Standards
Using additive manufacturing allows layered materials to be made with a variety of materials such as plastic, metal, concrete, and maybe even someday human and other biological tissue. Even though a human ear and other organs have been 3D-printed successfully, there is still much more work that needs to be done with printing human material, but materials frequently used in product manufacturing have been often created through this process. Standards that provide provisions on materials used specifically for additive manufacturing include:
ASTM F3049-14 - Standard Guide for Characterizing Properties of Metal Powders Used for Additive Manufacturing Processes
ASTM F3055-14A - Standard Specification for Additive Manufacturing Nickel Alloy (UNS N07718) with Powder Bed Fusion
ASTM F3056-14E1 - Standard Specification for Additive Manufacturing Nickel Alloy (UNS N06625) with Powder Bed Fusion
Common Plastics Used In Additive Manufacturing
Several plastics are suitable materials to compose products through additive manufacturing. The easiest material to work with is Polylactic Acid (PLA), a biodegradable thermoplastic derived from renewable resources, such as cornstarch, sugar cane, tapioca roots, or potato starch, making it the most environmentally friendly to use. Because of its natural origins, PLA is a popular material used in the additive manufacturing and 3D printing of medical suturing and surgical implants. The human body rarely rejects surgically implanted PLA materials, and they break down within two years.
Another material often used in additive manufacturing is Acrylonitrile Butadiene Styrene (ABS), since it is a low cost plastic that is easy to fabricate. Outside of 3D printing, ABS is often used in food processing applications. Another common use for this material is as the primary component of modern Lego bricks. While Lego mass-produces its products with conventional methods of manufacturing, the company does use 3D printing to create ABS-based testing models prior to distribution. ABS materials and alloys suitable for manufacturing are covered in ASTMD4673-16 - Standard Classification System forAcrylonitrile-Butadiene-Styrene (ABS) Plastics and Alloys Molding and Extrusion Materials.
Polyvinyl Alcohol (PVA), a special plastic that is water soluble, is also occasionally used in certain 3D printers in order to provide a support structure to an object with overhang issues. Once printing is completed, the object can be placed in water to remove the support structure.