FDM stands for Fused Deposition Modeling. It is a type of 3D printing process that can be understood as drawing with a specific “hot-glue” gun. It is also rebranded with an open source community like Fused Filament Fabrication, abbreviated FFF. It works by extruding a material to first point through a nozzle for crossing the section of an object, and then vertically move up, and keep repeating the process for all respective new layers.
The printer has a nozzle, which also contains the resistive heater that will melt plastic, while it flow through a tip, before forming the layers, which also contributes to what make the printer so productive. The plastic that is extruded would then be instantly hardened, as its bonding to layer that is beneath it. Repeating such process would builds up the object, one layer at a time, until all layers are covered.
The kind of the printing quality with this technology is largely dependent on height of the layer, because the thinner cross sections are, then the lesser the chance they would be noticed, which make the objects smoother. It is typical for FDM cross section’s resolution to be between 75 and 300 microns. Its technology is also common in desktop 3D printers, and is not that expensive, for professional printers.