Polymer Material Extrusion for Industrial Production: Filament FFF/FDM, Pellet Extrusion and Reactive Screw/Large-Format Extrusion

Polymer material extrusion includes materially different architectures that share selective deposition through a nozzle. In filament-fed systems, the solid filament is both feedstock and force-transfer element. Pellet-fed systems use a screw to convey, melt, mix and pressurise granules. Reactive thermoset systems within this review use a melt-capable screw or large-format extrusion head to convey, thermally condition and pressurise material before controlled gelation or cure during or after deposition. This qualitative engineering review compares those routes from released feedstock to accepted component. It examines conditioning, feeding, melting or mixing, pressure generation, nozzle flow, bead placement, transient starts and stops, inter-road contact, molecular interdiffusion, crystallisation, chemical conversion, fibre orientation, cooling, support removal, finishing, inspection and change control. Primary studies show that bond formation occupies a short thermal window, extrusion can orient and disentangle polymer chains, semi-crystalline transformations can restrict welding, and increased flow changes feature scale, thermal history and motion demand. Pellet and filament routes can produce similar extrudates without producing equivalent parts, while reactive screw or large-format extrusion introduces feed-state, residence, gel-time, exotherm and cure-shrinkage constraints. Large-format and reinforced-polymer routes can increase deposition capacity or stiffness within bounded applications, but may intensify anisotropy, void, surface, nozzle-wear and machining burdens. The resulting selection gate uses accepted-component requirements and complete-cell throughput rather than machine headline values. Construction printing, concrete and macroscopic high-volume production are outside scope.

3Dresyns Engineering Review ER-140, version 0.2. Provider-neutral technical review.