Aluminum eddy current testing uses electromagnetic responses to investigate a defined inspection question. Agree the material condition, target discontinuity, examined region, procedure and acceptance requirement before requesting a report.
For procurement, a useful result identifies exactly what was inspected and how findings were evaluated. The method name alone cannot establish that every part or internal location is acceptable.
Four scope checks before ordering inspection
- Name the feature and inspection objective.
- Confirm the procedure and relevant reference pieces.
- Identify coverage and limitations.
- Connect findings to the required acceptance decision.
On this page
1. Define the purpose of aluminum eddy current testing
TWI’s eddy current testing overview describes an electromagnetic method for conductive materials. An energized coil interacts with the part; the resulting response is interpreted for the intended inspection.
Specify whether the request concerns a named discontinuity, material conductivity or another characteristic. These are different test objectives. A conductivity reading does not automatically constitute a crack-inspection report.
TWI explains that conductivity, permeability and discontinuities affect the response. The provider therefore needs the actual material and part condition, rather than just the word “aluminum.”
Give the provider the alloy and temper record, product form, drawing revision, geometry and surface condition. State whether the inspection concerns stock, a cut blank or a component after machining or joining.
Our aluminum conductivity guide addresses units and material-property reporting. Keep that objective distinct from the discontinuity inspection discussed here.
2. Ask how the reference pieces support the procedure
Request the procedure identity and revision. Ask the inspection provider how the selected equipment, probe and reference pieces address the specified part and target condition.
TWI describes appropriate reference standards as essential to the procedure. Its discussion relates reference blocks to the material condition and geometry, and uses artificial defects for defect-detection references.
For a buyer, the practical question is whether the reference supports this inspection task. Do not assume that a demonstration on a convenient block establishes suitability for a hollow extrusion, a machined bore or an angled cut face.
Have the qualified inspection team define the method and its required validation. Retain the personnel and process documentation required by the order. This article does not supply a scanning recipe or a universal qualification requirement.
Keep depth and orientation in the review
TWI explains that sensitivity decreases with depth and that frequency affects penetration and sensitivity. A quoted frequency should remain part of the procedure; it is not a universal guarantee of a particular detection depth.
TWI’s advantages and limitations FAQ also explains that defect orientation matters: a planar defect that does not interrupt the current path can be missed. Ask whether the target condition and geometry are addressed by the proposed inspection.
3. Map the examined regions and excluded areas
Mark the required area on the drawing. Identify the relevant surfaces, ends, bores or joints and the stage at which they are examined. Ask the provider to record inaccessible or excluded regions.
Retain the inspected quantity and individual or group identities. A count of inspected pieces does not describe the region examined on each piece. A report for cut ends should not be expanded into a report for the full tube length.
TWI’s FAQ notes that complex geometry can make it harder to distinguish geometry-related signals from defect indications. Use that point to request a procedure-specific explanation, rather than deciding suitability from a photograph.
If an array system is proposed, clarify the actual scan coverage. TWI describes eddy current arrays as multiple sensing elements arranged to cover a larger region in a pass. A wider probe still needs an identified inspection map.
Keep any sampling plan separate from the method selection. The inspection-sampling guide addresses represented quantities and the acceptance plan. Neither a fast scan nor a larger sensor automatically authorizes reduced batch coverage.
4. Read findings with their acceptance basis
TWI emphasizes careful signal interpretation to separate relevant and non-relevant indications. A displayed response should therefore come with the inspection team’s evaluation, not an unsupported defect label.
Request the part identities, procedure, reference information, coverage, recorded findings and applicable acceptance criteria. The report should identify the requirement used for the decision and the person responsible for the disposition.
If the report states that no relevant indications were found, retain its stated scope with that conclusion. It should not become a blanket statement that the entire delivery contains no possible defects.
Keep raw or supporting records required by the procedure available for review. If a finding needs additional evaluation, retain the original result and the agreed next action with the affected part identity.
A penetrant inspection report concerns its own method and surface-access scope. Do not substitute one report for another inspection requirement without the responsible technical owner’s approval.
A fictional calculation: pieces and regions are separate
Assume a fictional delivery of 40 tubes. The inspection plan in this example names two end regions on each tube. There are therefore 40 × 2 = 80 named end regions.
Suppose a development review examines both named ends on eight identified tubes. That covers eight of 40 pieces and 16 of 80 named end regions: 20% in each count. These numbers describe invented coverage only; they do not establish a valid sampling plan or acceptance result.
| Record | Meaning and boundary |
|---|---|
| 8 identified tubes | Does not establish inspection of all 40 pieces. |
| 16 named end regions | Does not establish inspection along each full tube. |
| Reported findings | Need the method, coverage and applicable decision criteria. |
If the requirement later changes to a machined bore, retain a revised scope. An earlier end-region report does not automatically cover the new feature or the condition after further processing.
Connect the inspection scope to the cutting handoff
Identify the supplied stock, cut lengths, quantities and required end condition. Mark any inspection-related surfaces and preserve the material and part identities through cutting and later processing.
Agree when inspection occurs and which party provides the required report. If finishing or machining follows cutting, make the relevant stage visible in the order. Link the report to the actual stage examined.
Send JiurunCut the profile drawing and cut list to discuss the cutting scope. Keep NDT method selection, examination and acceptance with the appointed inspection provider and responsible quality owner.
Common questions
Can eddy current methods be used on aluminum?
Yes, aluminum is conductive. Suitability for a particular inspection still depends on the target condition, geometry and qualified procedure.
Does a conductivity measurement prove the part has no cracks?
No. Identify the actual measurement objective. A material-property result and a discontinuity inspection address different requirements.
Does an array mean every region was inspected?
No automatic conclusion follows. Review the recorded scan area, part identities and excluded regions.
Does no relevant indication mean the entire batch is defect-free?
Keep that conclusion within the named procedure, examined areas and represented quantities. It cannot establish every possible internal or external condition.