Fused deposition modeling (FDM) is a common additive manufacturing (AM) technology able to fabricate physical prototypes directly from virtual model without geometrical complexity limitations. Initially used to create concept models to help product design stage, FDM developed as regard materials, accuracy, and the overall quality of the output improved, becoming suitable for end use. At present, it is employed in process chains to significantly shorten product development times and costs and to produce parts in small and medium batch. A critical drawback which inhibits its diffusion is the obtainable accuracy. Only few indications, relating the dimensional deviations, exist, and they are conflicting each other, not allowing a reliable prediction. In this paper, a geometrical model of the filament, dependent upon the deposition angle and layer thickness, has been developed in order to predict the obtainable part dimensions. The model has been validated by an experimental campaign. The specimens have been investigated by means of profilometer analysis in order to study macrogeometrical and microgeometrical aspects. Finally, a case study highlighted the reliability of the model. The direct implication of this work is the capability, in process planning, to know in advance if the FDM part dimensions will satisfy the specification and the component will fit with others. Moreover, this model can be employed to choose the suitable manufacturing strategy in order to comply with industrial constrains and scopes. © 2014 Springer-Verlag London

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Purpose – The purpose of this paper is to study the integration between this technology and barrel finishing (BF) operation to improve part surface quality. Fused deposition modeling (FDM) processes have limitation in term of accuracy and surface finishing. Hence, post-processing operations are needed. A theoretical and experimental investigations have been carried out. Design/methodology/approach – A geometrical model of the profile under the action of machining is proposed. The model takes into account FDM formulation and allows to predict the surface morphology achievable by BF. The MR needed in the model is obtained by a particular profilometer methodology, based on the alignment of Firestone–Abbot (F–A) curves. The experimental performed on a suitable geometry validated geometrical model. Profilometer and dimensional measurements have been used to assess the output of the coupled technologies in terms of surface roughness and accuracy. Findings – The coupling of FDM and BF has been assessed and characterized in terms of obtained part surfaces and dimension evolution. Deposition angle strongly affects the BF removal speed and alters nominal dimensions of part. The geometric profile model gave interesting information about profile morphology and machining mechanism; moreover, the height prevision allows to estimate BF working time to accomplish part requirements. Research limitations/implications – The prediction of the geometric profile as a function of FDM fabrication parameters is a powerful tool which permits to investigate surface properties such as mechanical coupling or tribological aspects. The coupling of BF and FDM has been assessed and now optimization of this process can be performed just evaluating effects of parameters. Practical implications – This research has been focused to an industrial application, and results can be used in a computer-aided manufacturing. The prevision of surface obtainable by this integration is a tool to find the part optimum orientation to accomplish the drawing requirements. Both the experimental findings and the model can guide operator toward a proper process improvement, thus reducing or eliminating expensive trial and error phase in the post-processing operation of FDM prototypes. Originality/value – In this paper, a novel model has been presented. It allows to know in advance profile morphology achievable by a specific surface of a FDM part after a determined BF working time. A particular application of FA curves gives the MR values.

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