Effects of 3D-printing processing parameters on FFF parts' porosity: outlook and trends

The filament material extrusion (ME) process manufactures functional components for a wide range of personalized applications in medicine, fashion and remanufacturing cases, or customized batch production for aviation and automotive industries. Therefore, structural and welding parameters affect porosity during 3D printing and are of paramount interest concerning the parts' mechanical response to static and dynamic loadings. This work aims to arrange the literature's experimental findings of crucial processing parameters' effects on the fused filament fabrication (FFF) part's porosity and structural strength. Therefore, the materials and structure parameters, including the filament material properties, deposited strand geometry, infill rate, infill pattern design type and orientation, and part orientation, as well as welding parameters such as material flow, nozzle temperature, bed temperature, printing feed, and environmental conditions, are critically reviewed and study in profoundness regarding porosity and mechanical loading of 3D printed parts. Experimental studies are critically examined, emphasizing the effects of parameters and interactions between them.