FDM
Fused deposition modeling [FDM] is a form of 3D printing where plastic in the form of filament or pellets is extruded through a nozzle and deposited in layers to form the final product.
Functionally, FDM is limited in the possible quality of prints. Surfaces are frequently possible to print within 0.1mm or ~0.005in, but surface quality is much lower. This means parts are nominally correct when averaged over a few square centimeters like when measuring with calipers, but in reality the parts do not operate like a plastic part machined to a 0.1mm tolerance. This surface quality is limited by the layer height, the effect of the nozzle dragging across top surfaces, and shrinkage. A typical layer height is 0.2mm with a lower bound of around 0.1mm. Even at this extrusion height, the surface will retain artifacts from the plastic squishing out of the nozzle which creates very fine rounded corners.
Achievement of maximum resolution on an FDM printer is dependent on the quality of filament, the speed of the print, and the calibration of the machine. With a well calibrated printer and a quality filament, much of the quality comes down to speed. Maximum accuracy occurs at lower speeds. This produces a balancing act between acceptable accuracy for the application and time spent printing. Technologies like input shaping can allow for printing at much higher speeds without negatively impacting quality.
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