Evaluating region-specific defect-induced geometric deformations in monolayer parts to support monitoring of the FFF additive manufacturing process

Abstract The Additive Manufacturing (AM) process of Fused Filament Fabrication (FFF) deals with the manufacturing of parts by adding multiple layers of fused material. The FFF process is often used for rapid prototyping or the fabrication of small batches of highly specific parts. However, FFF’s reliability is comparatively lower than other manufacturing processes. The accuracy of a product’s geometry in the FFF process is significantly influenced by process errors such as nozzle clogging, improper build platform temperature settings, and incorrect leveling calibration, leading to defects like geometric deviation or deformation. In this study, an investigation is performed on the geometric deformations in monolayer parts produced through the FFF process, focusing on the effects of simulated extruder clogs and under-extrusion region-specific induced defects. A dataset composed of images obtained from monolayer parts was produced, and the analysis employed MATLAB’s Image Processing Toolbox to perform histogram-based statistics, area measurements, and pixel-to-millimeter conversion, enabling the assessment of angle divergence and deformation extent across three printing conditions: regular printing, under-extrusion (D1), and retraction (D2). Results from the D1 condition indicate moderate geometric deformation, with 36% of the parts showing angle deviations between 0.6 and 0.8 degrees. Deformations ranged up to 1.8 degrees, and affected areas varied from 10 to over 50 mm², with most concentrated between 30 and 35 mm². These results reveal consistent yet variable impacts of under-extrusion. In contrast, D2 parts exhibited smaller, more centralized defects, with affected areas mostly between 10 and 18 mm², peaking around 14 mm². Despite their smaller size, the central region of the defects poses greater risks to structural integrity. The findings emphasize the criticality of early detection and stringent quality control in the FFF process, revealing that even minor and region-specific initial layer defects can significantly compromise the quality of finished products.