The role of FFF process parameters on impact strength: a review

Fused filament fabrication (FFF) is a widely used additive manufacturing technique which, via plastic filament extrusion, fabricates parts via layer-by-layer build-up. Mechanical properties of parts can be optimised by control of print parameters. Impact strength is an important property which relates to a parts response under dynamic loading. This article reviews the most critical processing parameters affecting impact strength, including build orientation, raster angle, shell thickness, infill density and pattern, layer thickness, nozzle temperature, and print speed. Parameters are observed in literature to directly impact the micro and mesostructure and, as such, impact strength. The lack of standardisation in print and impact technique of FFF parts makes intra-study comparisons of the available literature difficult, whilst interdependencies between print parameters adds additional complexity. Here, a careful analysis of all available literature is conducted, relating observed trends to variations in structure, allowing for impact strength optimisation via print parameter guidelines to be generated.