This is the case with 3D printers that use brass nozzles in their print heads. Fusion3, on the other hand, made the decision to use E3D all-metal hotend and incorporate a hardened steel nozzle. Unlike brass nozzles, hardened steel nozzles do not degrade when using abrasive filaments. For some infused materials, especially those that incorporate metals that are irregularly sized, we recommend using the optional .6MM print head.