Structured light is a line-of-sight method. If the geometry that matters is inside a casting, a welded assembly, or a cooling passage, no amount of exterior scanning reconstructs it. Industrial computed tomography (CT) measures through the volume.
When we recommend CT
- Internal features that drive function (passages, undercuts, trapped cores)
- Assemblies you cannot or should not tear down
- Porosity or wall-thickness questions alongside dimensional work
- Small parts where a single CT volume is cheaper than a fixture farm
CT is not automatically “more accurate than CMM.” Voxel size, material, and reconstruction settings dominate. For tight external datums we still correlate with CMM or an optical scan of the exterior.
How it shows up in a Bolton Works quote
You will see CT as a line item when the photos or CAD show hidden geometry, not as a bundled mystery. Exterior-only jobs stay on structured light and CMM — see metrology.
If you think the issue is inside the part, say so in the quote brief. That one sentence changes the method.
— Bolton Works