With this version, a thread is used to pull in the welding rod on the screw1. In the process, it passes a feed-in sleeve2 preventing the rod from twisting. Once inserted, the knife3 cuts the rod. The screw spiral moves the rod forward. Heat penetrates the extrusion unit from the outside, starting the plasticizing process and helping it continue during operation. The external heat is generated by the hot gas appliance4 in the form of hot air which then flows around the extrusion unit in the preheating chamber5. Frictional heat is also generated by the compression and friction. This causes the weld filler metal to be plasticized and to be mixed into a homogeneous mass. The extrudate then exits the nozzle6. This technology gives the FUSION extruder a simple and robust design.