Additive manufacturing, also commonly referred to as 3D Printing is the process of building three dimensional structures or components from the ground up, usually layer by layer. There are seven main categories of additive manufacturing processes, as defined by the ASTM Committee F42 on Additive Manufacturing Technologies. These include:
- Powder Bed Fusion
- Vat Polymerization (Stereolithography)
- Material Extrusion (Fused Deposition Modeling)
- Material Jetting
- Binder Jetting
- Sheet Lamination
Although the above technologies are all classed as additive manufacturing processes, the techniques, equipment and materials used can be quite different, as can their material characterization requirements. For example, the efficiency of powder bed additive manufacturing processes and the quality of finished components is largely dependent on the flow behavior and packing density of the powders used and hence particle size and particle shape are critical parameters.
Microstructure, phase composition and elemental composition are also important properties of the metal or alloy powders. These may impact sintering behavior and hardness of powders as well as the chemical and physical properties of the final components.
For material jetting, extrusion and vat polymerization, where the deposited material is in liquid form, rheological properties are critical since they affect processability of the fluid, the liquid-solid transition of the deposited material and the mechanical properties of the final solid structure. Such properties are dependent on microstructural characteristics such as the molecular structure and molecular weight of polymers and oligomers used, or in the case of filled systems, particle size and particle shape also.