Filament fabrication and subsequent additive manufacturing, debinding, and sintering for extrusion-based metal additive manufacturing and their applications: A review

Additive manufacturing (AM) is suitable for fabricating components made from expensive, high-strength metallic materials, which can be designed and created with minimal material waste during the layer-upon-layer addition process. The development of new products has already made great use of AM technology for prototyping. Today, components created by AM are used directly in the finished product, and in some instances, AM components are used as spare parts across numerous industries. However, the cost of currently available metal additive manufacturing (AM) machines for metals based on selective laser melting and the cost of part manufacture is very high. Furthermore, the processes used by these technologies produce waste metal powder, creating an adverse effect on the environment. As a result, there is an increasing demand for new techniques with environmental friendliness, high mass production rates, and low production costs. In light of this, extrusion-based metal AM techniques, which utilize the fused filament fabrication (FFF) approach, are a great alternative to the current laser-based metal AM solutions. The extrusion-based metal printing technique uses customized filaments with metal particles distributed in a sacrificial polymeric binder. A FFF printer is utilized to 3D print the green part. The polymeric binder is removed from the printed parts using a catalytic solvent or debinder (depending on the step). The final metallic parts are obtained after the sintering stage. This article thoroughly discusses all aspects of filament fabrication, AM of green parts, debinding, sintering, and post-processing of green and sintered parts in extrusion-based metal AM.