The dimensional and geometrical quality of additively manufactured parts must be increased to match industrial requirements before they can be incorporated to mass production. Such an objective has a great relevance in the case of features of linear size that are affected by dimensional or geometrical tolerances. This work proposes a design for additive manufacturing strategy that uses the re-parameterization of part design to minimize shape deviations from cylindrical geometries. An analysis of shape deviations in the frequency domain is used to define a re-parameterization strategy, imposing a bi-univocal correspondence between verification parameters and design parameters. Then, the significance of variations in the process and design factors upon part quality is analyzed using design of experiments to determine the appropriate extension for modelling form deviation. Finally, local deviations are mapped for design parameters, and a new part design including local compensations is obtained. This strategy has been evaluated upon glossy surfaces manufactured in a Vero™ material by polymer jetting. The results of the proposed example showed a relevant improvement in dimensional quality, as well as a reduction of geometrical deviations, outperforming the results obtained with a conventional scaling compensation.

A notable constraint to the industrial application of additive manufacturing processes is the lack of geometric accuracy of the parts produced. In-situ inspection systems, therefore, need to be developed to detect and compensate for any geometric deviations that appear during the process. This article proposes a noncontact system for the digitization of deposited material layers, based on a contact image sensor extracted from a low-cost flatbed paper scanner. The viability of using this sensor for such a purpose was analyzed by integrating it in a tailor-made test bench with the dual capability of fused filament fabrication and digitizing of deposited layers. The integration procedure includes analysis of the sensor's operating principle, development of the hardware and control routines required for PC operation, and image processing. To validate the integration, two specimen parts were built and digitized in the test bench. The measurements performed on the captured images showed low discrepancies with respect to those obtained on a coordinate measuring machine.

One of the limiting factors for industrial application of additive manufacturing (AM) is the lack of geometrical accuracy of manufactured parts. To improve precision, non-contact sensors should be integrated into AM machines, capable of performing in-situ inspection of the part and being able to detect and compensate for the actual geometrical errors. A non-contact digitizing system is proposed in this work for the inspection of the deposited material layers, based on a Contact Image Sensor (CIS) extracted from a commercial flatbed paper scanner. In order to integrate this sensor in an AM machine, a methodology was developed that includes the sensor operation analysis, the design of the necessary hardware and software to be externally controlled and the subsequent processing of the captured images. Results prove that the CIS sensor can be integrated in any device external to the original scanner.

Material Extrusion (MEX) currently stands as the most widespread Additive Manufacturing (AM) process, but part quality deficiencies remain a barrier to its generalized industrial adoption. Quality control in MEX is a complex task as extrusion performance impacts the consistency of mechanical properties and the surface finish, dimensional accuracy, and geometric precision of manufactured parts. Recognizing the need for early-stage process monitoring, this study explores the potential of integrating Laser Triangulation Sensors (LTS) into MEX/P manufacturing equipment for layer-wise 3D inspections. Using a double-bridge architecture, an LTS-based sub-micrometric inspection system operates independently from the manufacturing process, enabling comprehensive digitization and autonomous reconstruction of the target layer’s topography. Surface texture is then computed using standardized indicators and a new approach that provides insight into layer quality uniformity. A case study evaluating two alternative extruder head designs demonstrates the efficacy of this integrated approach for layer quality characterization. Implementing a generalized layer-wise procedure based on this integration can significantly mitigate quality issues in MEX manufacturing and optimize process parameter configurations for enhanced performance.

Additive manufacturing (AM) has faced challenges in achieving the part accuracy required for industrial adoption. Most research has focused on offline inspection of geometric deviations in test parts. This paper introduces a novel approach to enhance part accuracy and process control in Polymer Extrusion AM (MEX/P) by integrating in-situ digitising and compensation systems. A custom 3D-printing test bench was developed for this purpose, incorporating a laser-stripe sensor for real-time measurement of layer contours during the printing process. The paper details the integration procedure, including sensor installation, calibration, and validation test. To validate the system accuracy, irregular-shaped test parts were scanned using the integrated sensor and compared to ground truth measurements from a Coordinate Measuring Machine. The results demonstrated close agreement between the two measurement methods. The methodology was applied to a case study, wherein digitised layer contours were recognised and their geometric deviations from the nominal contours were measured and compensated for. This process also accounted for the thermal shrinkage experienced by the part during cooling. This resulted in a significant improvement in part quality, with virtually eliminated average layer contour deviations and a reduction in error dispersion by over 50%. The proposed methodology, validated for parts with uniform complex cross-sections, can be extended to the production of serial components with any layer shape including both outer and inner contours.