Estimation of measurement uncertainty of 3-D metal printed specimen of H13 tool steel fabricated via metal fused filament fabrication process using 3D scanner

Abstract

This work has presented dimensional characterization and a “Guide to the Expression of Uncertainty in Measurement” (GUM) compliant measurement uncertainty evaluation of metal parts fabricated by metal fused filament fabrication process (M-FFF). A high-resolution handheld optical 3D scanner has been used for dimensional measurement of the printed specimens. Four different geometries have been printed from H13 tool steel, washed, sintered, and then digitally inspected to investigate dimensional deviations and further quantify the reliability of scanner-based metrology. Each specimen has been scanned three times, and dimensional deviation analyses have been conducted by means of CAD-to-scan comparisons using Artec Studio 19. Systematic deviations based on printing-induced shrinkage, surface topology, and scanning conditions have been revealed, and measured deviations across all samples have ranged from –0.999 mm to +0.989 mm. Measurement uncertainty has been estimated via both Type A (repeatability) and Type B (instrument and environmental factors) contributions. The following factors have been considered for Type B uncertainty evaluation: scanner point accuracy, resolution, alignment error, thermal expansion, and distance-dependent error. Repeatability and alignment/registration error have been identified as the main uncertainty contribution factors. The combined standard uncertainty has resulted in 122.7 μm, with an expanded uncertainty of approximately ±0.247 mm at k=2.015, 95% confidence level. It has been concluded that the presented and validated uncertainty budget offers a realistic tolerance band for industrial qualification of MFFF components, while enhancing the reliability of non-contact optical metrology. The findings have allowed a robust framework to be established for metrology-driven process validation, quality assurance, and industrial adoption of MFFF, which caters for very diverse applications, ranging from aerospace, automotive, and tooling to medical devices, part repairing, complex part dimension measurement and defense manufacturing.