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<p>Reverse engineering of degraded service components becomes difficult if there is uncertainty in the nominal geometry due to corrosion, fracture or missing material, and original drawings are not available. This study proposes a two-stage dimensional validation procedure for a worn cast-iron foot valve, which can be broken down into reconstruction-stage deviation and fabrication-stage deviation. The valve was scanned with structured light and converted to a watertight mesh of around 3.1&#xa0;million facets. The damaged geometry was recreated in the CAD environment using a combination of NURBS surface fitting, symmetry guided repair and controlled fitting of missing or corroded geometry. A PLA prototype was then fabricated by fused deposition modelling using 0.15&#xa0;mm layer height, 100% infill, and 45&#xa0;mm/s print speed. Dimensional accuracy was evaluated using signed deviation mapping, rigid alignment, and a ± 2&#xa0;mm tolerance band. In Stage 1, the CAD-scan comparison produced an RMS deviation of 2.67&#xa0;mm, with 36.5% of the surface lying within the tolerance band. In Stage 2, the CAD-printed-part comparison showed an RMS deviation of 2.9&#xa0;mm and 35% in-tolerance surface. The small RMS increase of + 0.23&#xa0;mm indicates that, under the selected printing conditions, FDM reproduction introduced only a limited additional global deviation relative to the CAD-scan deviation. The main contribution of this work is the proposed two-stage error-separation strategy, which provides traceable evidence of dimensional error propagation across scanning, CAD repair, and physical prototyping. The workflow is suitable for preliminary geometric prototyping of degraded cast components, while functional reuse requires further datum-based and feature-level validation.</p>

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Two-stage dimensional accuracy verification of a reverse engineered degraded cast iron foot valve using structured-light scanning, CAD repair, and FDM prototyping

  • 期刊论文

  • 发表日期：

    2026年7月7日

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  • Sreeram Reddy Gundeti,
  • Putha Prasad Kumar,
  • Sunanda A,
  • Ravi Kiran Chintalapudi,
  • Sowmya Krishna,
  • J. Jagadesh Kumar

摘要

Reverse engineering of degraded service components becomes difficult if there is uncertainty in the nominal geometry due to corrosion, fracture or missing material, and original drawings are not available. This study proposes a two-stage dimensional validation procedure for a worn cast-iron foot valve, which can be broken down into reconstruction-stage deviation and fabrication-stage deviation. The valve was scanned with structured light and converted to a watertight mesh of around 3.1 million facets. The damaged geometry was recreated in the CAD environment using a combination of NURBS surface fitting, symmetry guided repair and controlled fitting of missing or corroded geometry. A PLA prototype was then fabricated by fused deposition modelling using 0.15 mm layer height, 100% infill, and 45 mm/s print speed. Dimensional accuracy was evaluated using signed deviation mapping, rigid alignment, and a ± 2 mm tolerance band. In Stage 1, the CAD-scan comparison produced an RMS deviation of 2.67 mm, with 36.5% of the surface lying within the tolerance band. In Stage 2, the CAD-printed-part comparison showed an RMS deviation of 2.9 mm and 35% in-tolerance surface. The small RMS increase of + 0.23 mm indicates that, under the selected printing conditions, FDM reproduction introduced only a limited additional global deviation relative to the CAD-scan deviation. The main contribution of this work is the proposed two-stage error-separation strategy, which provides traceable evidence of dimensional error propagation across scanning, CAD repair, and physical prototyping. The workflow is suitable for preliminary geometric prototyping of degraded cast components, while functional reuse requires further datum-based and feature-level validation.