Non-Destructive Evaluation of Vat-Photopolymerised Parts

Non-destructive evaluation is often presented as a capability that a part either has or does not have. For vat-photopolymerised components that framing fails at the first question, because the useful question is not whether a method can image the part but whether it can detect the specific discontinuity that would make the part unacceptable. This review organises non-destructive evaluation of vat-photopolymerised parts around defect class rather than around instrument, and states what the published evidence does and does not support. The central finding is negative and should be read as the paper’s principal contribution: this review located no probability-of-detection study for any polymer additive-manufacturing process, no computed-tomography-versus-destructive-sectioning validation on a vat-photopolymerised part, and no additive-manufacturing non-destructive-testing standard whose scope includes polymers. The quantitative detectability literature is metallic, and the mechanism that limits detection in metals — attenuation and lack-of-fusion morphology in a high-atomic-number matrix — is not the mechanism that limits it in a low-attenuation crosslinked network. The review’s own central hypothesis is that cure-state defects may present substantially less radiographic contrast than voids or open separations; that hypothesis is not established by any located measurement, and stating it as one would answer the question this review exists to pose. The review therefore separates what can be inspected today with a defensible argument, what can be inspected only with locally generated evidence, and what currently cannot be qualified at all. It proposes an evidence architecture: defect-class definition, seeded or known defect population, resolution and contrast budget, correlation against a destructive reference, and an acceptance threshold expressed against detectability rather than against image appearance. A part that has been scanned is not a part that has been inspected.