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FDM, SLA, SLS, MEX 3D printing technologies

Knowing a little about the main types of 3D printing technologies can help you decide which road to take.

Key phrases linking here: fdm, sla, sls, mex 3d printing technologies, fdm, sla, sls, mex - Learn more

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Fused deposition modeling (FDM), also known as fused filament fabrication (FFF), is the most widely used. They are 'line drawing" devices that follow the path defined in a G-Code file. Consumer FDM printers work by extruding thermoplastic filaments (such as ABS, PLA or TPM), through a heated nozzle, near-melting the material and applying it layer by layer (to the object that glues itself to a build platform). Industrial printers can extrude all manner of materials, even molten metal.

Material extrusion (e.g. MEX) printers are "paste pushers", the most accessible and practical for ceramics. Material is pushed through a nozzle along a path, depositing in layers on a build platform (which remains stable on a delta printer but moves on others). Pastes can be made from ceramic or metal powders (with optional uV hardeners, binders, dispersants). This technology is also used for concrete, biogels, foods, and more.

SLA (Stereolithography) 3D printers go back to the 1970s. They are "pixel burners". They focus light to selectively cure (harden) the pixels of successive layers of liquid photopolymer resin. Most devices maintain the build platform barely submerged at the liquid’s surface (held in a container or vat, the process is thus called VAT polymerization). The printer employs a uV light source, directing it to specific pixels using projector or shining the light on an LCD panel that can block or permit light at each one (these are thus also called DLP or LCD printers). A laser can also be used - as it rasterizes the slice by turning on whenever it encounters a pixel.

Selective laser sintering (SLS) 3D printers use a laser to selectively sinter small particles of powder into a solid structure. Like SLA, the laser is acting as a pixel-burner. A new thin layer of powder is deposited over already hardened material for each laser pass. The finished object thus exists in a matrix of powder that must be removed.

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