Non-Destructive Testing (NDT) Providers

How NDT methods qualify AM parts

AM parts can hide defects no surface inspection will catch — sub-surface gas porosity, lack-of-fusion stripes between melt tracks, internal cracks from residual stress, and trapped powder in unvented cavities. Traditional cast and forged parts share many of these failure modes, so the NDT toolkit (CT, ultrasonic, dye penetrant, X-ray, eddy current) was already mature when AM industrialised. What's new is the volume of internal geometry AM parts contain: lattice structures, conformal cooling channels, and topology-optimised webs all need inspection methods that can see inside the part — and that's where industrial CT has become the AM-defining inspection technology.

A typical regulated AM workflow runs three layers of inspection: visual + dimensional (CMM, structured-light scanning) for external geometry; surface NDT (dye penetrant for non-magnetic alloys, magnetic particle for ferrous) for surface-breaking defects; and volumetric NDT (industrial CT, ultrasonic, X-ray) for internal defects. For aerospace and medical first-article qualification, all three are typically performed on every part. For ongoing serial production, a sampling protocol is agreed with the customer — often 100% CT for safety-critical parts, statistical sampling for less-critical work.

NDT methods commonly applied to AM parts

NDT method selection by AM alloy and part class

How to specify NDT for AM parts

Reference the ASTM / ISO standard, not the technique. "Inspect per ASTM E2962 with acceptance criteria per customer drawing" gives the NDT provider an auditable framework to work from and ties the part to a published methodology that any NADCAP-accredited shop can execute.

Verify ASNT certification. NDT inspection results are only as good as the inspector. ASNT (American Society for Non-destructive Testing) certifies inspectors at Levels I, II, and III. For aerospace work, Level II is the minimum for routine inspection; Level III is required for technique development and signoff. Equivalent EN 4179 / NAS 410 certifications apply in European aerospace.

Specify NADCAP for aerospace. NADCAP (National Aerospace and Defence Contractors Accreditation Program) accredits the NDT provider's entire process system — equipment calibration, inspector certification, procedure documentation, customer audit trail. For any AS9100-flowed-down aerospace part, the NDT provider must be NADCAP NDT-accredited.

First-article CT, then sampling. Industrial CT is expensive (£200–£1,500 per part typical, higher for large-section steel and IN718). Standard practice is 100% CT for the first article and a sampling protocol thereafter — agreed in writing with the customer based on part criticality and process maturity.

Lead time and cost expectations for AM NDT

Standard NDT delivers in 3–10 working days from receipt of parts, depending on inspection method mix. Industrial CT scanning of a single small Ti aerospace bracket runs 1–4 hours of machine time; volumetric review and reporting adds another 1–3 days. Surface PT / MPI is faster — typically same-day to 2-day turnaround. Comprehensive first-article inspection packages (CT + PT + CMM + dimensional report) typically take 1–2 weeks.

Indicative pricing varies sharply by method: surface PT / MPI: £30–£90 / €35–€105 per part; X-ray / DR: £80–£200 / €95–€235 per part; industrial CT: £200–£1,500 / €240–€1,750 per part depending on alloy, size, voxel resolution, and reporting depth. CMM dimensional inspection is typically charged hourly (£70–£150 / €85–€175 per hour). Production sampling protocols dramatically reduce per-part cost compared with 100% inspection.

Related processes & materials

Frequently asked questions