the operation of joining two or more parts together by molten metal is called
Metalworking Welding is a fabrication process that joins materials, usually metals or thermoplastics, by causing coalescence. This is often done by melting the workpieces and adding a filler material to form a pool of molten material that cools to become a strong joint, but sometimes pressure is used in conjunction with heat, or by itself, to produce the weld.
Fused filament fabrication The 3D printer head or 3D printer extruder is a part in material extrusion-type printing responsible for raw material melting and forming it into a continuous profile. A wide variety of materials are extruded, including thermoplastics such as acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), high-impact polystyrene (HIPS), thermoplastic polyurethane (TPU), aliphatic polyamides (nylon),[1] and recently also PEEK.[2] Paste-like materials such as ceramics and chocolate can be extruded using the fused filament process and a paste extruder.[3]