Extrusion-Based Technology in Additive Manufacturing: A Comprehensive Review

Extrusion-based additive manufacturing (EB-AM) is a 3D fabrication process in which the material is heated and extracted through a nozzle before being deposited one layer at a time. It uses two types of technologies: filament and pellet extrusion. Filament extrusion machines entail transforming raw plastic pellets into a spool of filament; hence, these machines use limited materials. Pellet extrusion printers are more complex machines and use a screw inside a barrel. Screw feeds, transports, and melts the material before forcing it to be deposited at the required temperatures. Besides the complexities, a pellet extruder offers lower costs, higher speeds, and a wide variety of materials that can be used. This paper presents the development in extrusion-based 3D printing addressing filament and pellet-based printing issues, including filament breakage, nozzle clogging, in-line rheological monitoring, multi-color printing, material retraction, and cost-effectiveness of pellet-based extrusion additive manufacturing. To improve the material domain for 3D printing and utilize the advantages of filament and pellet-based extrusion, a hybrid form of 3D printer can be developed, capable of printing both filaments and pellet forms of material. This review work is intended to help young researchers in the field of EB-AM to understand the advances of this technology and its related complexities.