Solid Free-Form Fabrication

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= one of the two main forms (the other is CNC), of Digital Fabrication


Description

Dianna Pfeiffer:

"Solid free-form fabrication refers to what are currently called rapid prototyping and manufacturing (RP&M), or additive, processes. These tools create complex three-dimensional objects by successively layering up (adding) material into a complex physical form. They are comprised of an enclosed build-chamber, robotic head and material feed system, which is attached to, or includes a computer control interface.

Common methods of solid free-form fabrication are 3D Printing (3DP), Selective Laser Sintering (SLS), Stereo-lithography (SLA), Fused Deposition Modeling (FDM), and Laminated Object Manufacturing (LOM), among others.

Each of these methods automatically details a digital 3D model through the tool’s associated control software as a series of thin, horizontal cross-sections. These slices are then physically built-up from adhered powders of plaster, cornstarch or other resins in 3D Printing, or as laser-fused powders (polymers, ceramics, metal alloys and composites) for SLS. SLA methods are confined to laser-cured liquid resins, while FDM uses extruded filaments of thermosetting materials (ABS, epoxy). LOM adheres cutout cross-sections of paper, polymers, ceramics, or composites. (Schodek 281-293) In the active open-source maker communities of RP&M machines like RepRap, [email protected], and CandyFab, similar processes to FDM and 3DP use materials that users are able to configure themselves, ranging from chocolate to catalyzing plastics.

RP&M are largely hands-off machines in that the processes cannot be modified on the fly while the job is in progress, and are only minimally configurable with the software that controls the machine. Reportedly, only the very costly industrial versions and the relatively cheap DIY open-source varieties encourage user control over the fabrication process. This means the quality of the finished product is largely determined by two factors: the geometry of the digital model before it is sent to the machine and the machine’s default capabilities to handle it.

Two main drawbacks users continue to struggle with in free-form fabrication are imperfect surface resolution that results in stair-stepped vertical curvature, and the overall size constraints of the build chamber. There is also an underlying issue that these processes must overcome, namely that today’s additive processes primarily build objects from a single, inert material. Though developments are on the horizon, it is beyond most of these machine’s current capabilities to create objects, like integrated circuits, from combinations of material properties and behaviors within a single fabrication job.

(Gershenfeld 101) Nevertheless, the diminishing costs of these machines, and their increasingly Digital TOOLS, DISTRIBUTED MAKING & DESIGN desirable output coupled with ease of use have led them to be adopted into numerous environments whether professional, educational, industrial or residential." (http://scholar.lib.vt.edu/theses/available/etd-12152009-131820/unrestricted/Pfeiffer_DV_T_2009.pdf)