Which variable directly affects the quality of the filament deposition in FDM?

The variable that directly affects the quality of filament deposition in Fused Deposition Modeling (FDM) is nozzle speed. The nozzle speed influences how quickly the material is extruded and deposited onto the build surface or previously deposited layers. At the correct speed, the extruded filament can bond effectively with the previous layers and also achieve desired layer adhesion, surface finish, and overall dimensional accuracy.

If the nozzle speed is too fast, it can lead to under-extrusion, where not enough material is deposited, resulting in weak layers or gaps in the model. Conversely, if the speed is too slow, it may cause over-extrusion, leading to excessive material being deposited, which can lead to blobbing or sagging in the print. This balancing act is crucial, as it directly impacts print quality and performance of the final object.

Other factors, like filament diameter, also play a role in printing but are more about compatibility with the nozzle and ensuring the correct amount of material flows. Nozzle shape influences the characteristics of extrusion but does not directly correlate with deposition quality in the same dynamic way as speed. Finally, printing color pertains to aesthetic choices and does not impact the mechanical aspects of filament deposition.