The nozzle is the small metal tip at the end of an FDM 3D printer's hotend, with a precise bore—commonly 0.4 mm—through which molten filament is extruded onto the build surface.
The nozzle sets the width of each extruded strand in fused deposition modeling (FDM) 📝3D Printing and therefore governs the trade-off between print speed and detail. Its bore diameter, typically ranging from 0.1 mm to 1.0 mm with 0.4 mm as the industry default, determines how much material is laid down per pass: larger bores deposit more plastic and print faster at the cost of fine detail, while smaller bores capture intricate features but slow printing and clog more readily.
Nozzle material is chosen to match the filament. Brass is the standard, prized for high thermal conductivity and smooth heat transfer, but it wears quickly when fed abrasive composites. Hardened steel, stainless steel, and ruby- or tungsten-tipped nozzles resist abrasion from carbon-fiber, glow, or metal-filled filaments, trading some thermal conductivity for a working life many times longer than brass.
The nozzle threads into the heater block as the final stage of the hotend; it is not the extruder, which is the separate mechanism that pushes filament toward it. Because the nozzle is a common failure point—prone to clogging, wear, and partial blockages—it is treated as a routine consumable and matched to both the material and the target layer resolution.