CT Inspection (Industrial X-ray Computed Tomography)
Non-destructive internal and external metrology with industrial X-ray CT - the only technology that sees inside additively manufactured, cast or assembled parts without cutting them.
How it works
Industrial CT rotates a part between an X-ray source and a detector, capturing hundreds to thousands of 2D projections. Reconstruction software (Feldkamp / iterative algorithms) turns projections into a 3D voxel volume. Surface determination extracts a mesh from the voxels, which is then measured against CAD like any other scan - with the critical advantage that internal features are visible.
Typical accuracy
Metrology-grade CT systems (Zeiss METROTOM, Nikon MCT / XT H, Werth TomoScope, Waygate v|tome|x) achieve E-value MPEs in the 4-9 microns + L/100 range on well-conditioned parts, per VDI/VDE 2630.
Applications
- Additive manufacturing porosity, lattice and internal channel inspection
- Casting and moulding porosity, inclusion and wall-thickness analysis
- Assembled products - measure internals without disassembly
- Electronics: solder joints, BGA voiding, wire-bond integrity
- First-article inspection of complex AM and cast parts
- Failure analysis and root-cause investigation
Strengths
- • Sees inside the part - the only NDT/metrology technology that does
- • Full-volume measurement, not just accessible surfaces
- • Combines dimensional metrology with porosity, wall thickness and defect analysis
- • Non-destructive - critical for aerospace, medical and legacy parts
Limitations
- • Slow: full scans typically 30 minutes to several hours
- • Material and thickness limit penetration - dense/thick steel needs high-energy sources
- • Beam-hardening and scatter artefacts need careful correction
- • Capital cost and shielded room installation are significant
Why CT has moved from NDT into metrology
Ten years ago CT was primarily a defect-detection tool. Metrology-grade systems, VDI/VDE 2630 certification and improved surface-determination algorithms have moved it into the mainstream dimensional world - especially for additive manufacturing where internal geometry cannot be measured any other way.
Additive manufacturing and CT
AM parts are the killer application for CT: internal lattices, conformal cooling channels, wall thickness and porosity all matter and cannot be seen without cutting the part in half. A single CT scan gives dimensional conformance, porosity distribution and lattice fidelity in one dataset.
In-house vs outsourced CT
Not every UK manufacturer needs an in-house CT system. Bureau services (including several of our partners) are the pragmatic entry point for occasional AM or casting inspection. We help clients build a business case that compares outsourced cost, turnaround and IP risk against capital ownership.
Buying considerations
- Source: microfocus vs nanofocus, voltage (up to 225-450 kV or MeV linac)
- Detector: flat-panel vs curved, pixel pitch and dynamic range
- Metrology certification per VDI/VDE 2630 - not just NDT-grade
- Sample size and weight envelope, plus temperature-controlled enclosure
- Software: VGSTUDIO MAX, Zeiss GOM Volume Inspect, Nikon CT Pro / Inspect-X
- Radiation compliance - IRR17, HSE registration and local rules
FAQs
How thick a steel part can CT scan?+
Roughly 40-60 mm of steel on a 225 kV microfocus source, 100+ mm on a 300-450 kV system, and much thicker with linac sources. Aluminium, plastics and composites penetrate at much lower energies.
Is CT accurate enough for aerospace metrology?+
Yes - CT is now accepted for a growing range of aerospace AM and casting inspection tasks, provided the system is metrology-certified per VDI/VDE 2630 and the measurement plan includes calibrated reference artefacts.