Additive manufacturing builds titanium prostheses layer by layer — which also means every layer is a new chance for a defect to form. We use eddy-current inspection to find porosity and subsurface flaws that a visual check or a caliper simply cannot see, before the part is released.
A coil sweep flagging a subsurface pore
Additive manufacturing (AM) lets titanium prostheses be built with complex, patient-matched geometries that traditional machining can't achieve — porous surfaces for bone in-growth, lattice structures, patient-specific shapes. But building a part one fused layer at a time also opens the door to porosity, lack-of-fusion voids and microcracks buried inside the metal, invisible from the outside and, for an implant, unacceptable.
A well-established, non-destructive testing method — adapted here to the specific challenge of additively manufactured titanium.
A coil carrying an alternating current is passed close to the titanium surface, inducing small circulating "eddy" currents inside the conductive metal.
Anything that disturbs those currents — a pore, a crack, a change in density — changes the coil's electrical impedance in a measurable, repeatable way.
Software compares the impedance signature against a known-good baseline for the part, and flags the exact location where it deviates.
Unlike X-ray computed tomography, eddy-current inspection uses no ionising radiation and needs no special facility, so it can sit directly on the production floor. It's fast enough to check every part rather than a sample, and it's specifically sensitive to the conductivity changes that porosity and micro-cracking cause in titanium — the defect types that matter most for a load-bearing implant.
Small gas pockets trapped during fusion, which weaken the part locally.
Layers that didn't fully bond, a leading cause of fatigue failure in AM parts.
Fine subsurface cracks that visual and dimensional checks miss entirely.
Inconsistent material density across a build, signalling a process drift worth investigating.
Once a part is printed, a coil sweeps its surfaces and accessible internal channels, building an impedance map of the whole geometry.
The map is checked against the expected signature for that geometry and alloy, calibrated on parts of known, verified quality.
Any deviation is logged against its exact location on the part, producing a per-implant quality record for release and traceability.
Recurring defect patterns are fed back to the print process itself, so the next build starts from a better baseline.
We work with implant manufacturers to calibrate inspection to a specific alloy, geometry and print process.