Edge quality in Fused Deposition Modeling: I. Definition and analysis

Purpose – To discuss the problem of the geometric accuracy of edges in parts manufactured by the FDM process, as a preliminary step for an experimental investigation. Design/methodology/approach – Three geometric variables (inclination, included and incidence angle) were defined for an edge. The influence of each variable on the geometric errors was explained with reference to specific causes related to physical phenomena and process constraints. Findings – Occurrence conditions for all causes were determined and visualized in a process map, which was also developed into a software procedure for the diagnosis of quality issues on digital models of the parts. Research limitations/implications – The process map was developed by only empirical considerations and does not allow to predict the amount of geometric errors. In the second part of the paper, experimental tests will help to extend and validate the prediction criteria. Practical implications – As demonstrated by an example, the results allow to predict the occurrence of visible defects on the edges of a part before manufacturing it with a given build orientation. Originality/value – In literature, the geometric accuracy of additively manufactured parts is only related to surface features. The paper shows that the quality of edges depends on additional variables and causes to be carefully controlled by process choice

Edge quality in Fused Deposition Modeling: II. Experimental verification

Purpose – To provide an experimental evaluation of geometric errors on the edges of parts manufactured by the FDM process. Design/methodology/approach – An experimental plan was conducted by building parts in ABS thermoplastic resin on a commercially available machine with given combinations of the three geometric variables (inclination, included and incidence angle) defined in the first part of the paper. Edges on built parts were inspected on a 2D non-contact profilometer to measure position and form errors. Findings – The analysis of measurement results revealed that the edge-related variables have significant influences on the geometric errors. The interpretation of error variations with respect to the different angles confirmed the actual occurrence of the previously discussed error causes. As an additional result, quantitative predictions of the errors were provided as a function of angle values. Research limitations/implications – The experimental results refer to fixed process settings (material, FDM machine, layer thickness, build parameters, scan strategies). Originality/value – The two-part paper is apparently the first to have studied the edges of additively manufactured parts with respect to geometric accuracy, a widely studied topic for surface features