What a porosity requirement must say
Specify the casting region, the discontinuities assessed, the inspection method, the acceptance criterion and the production stage it applies to. Add the sampling plan, the report and what happens after a failed result. A reference standard on its own, or a phrase such as "low porosity", does not complete the agreement: the requirement has to describe an inspection both parties can perform and read the same way.
- Region. A zone on the drawing or a zone map, with boundaries an inspector can find without asking the designer.
- Condition. As-cast, after heat treatment, after machining, or as supplied.
- Discontinuity. Gas porosity, shrinkage, inclusions; separate criteria where needed.
- Method and reference. Film or digital radiography, CT, sectioning; the reference standard, edition and level.
- Sampling. Lot definition, quantity or frequency, selection method.
- Evidence and response. Images or measurements, part ID, who interprets, and the disposition route.
Choose the reference for the actual examination
Reference radiographs help classify indications; they do not choose a suitable level for your part. ASTM describes E155 as a basis from which application-specific acceptance requirements can be developed. Do not convert a radiographic severity level into a pore diameter or area percentage without a separately justified, agreed measurement.
| Examination | Reference to review | Scope question to resolve |
|---|---|---|
| Film radiography, aluminum castings | ASTM E155 | Material, section thickness, discontinuity category |
| Digital radiography, aluminum castings | ASTM E2422 | Suitability of the digital reference and the system |
| Film radiography, aluminum or magnesium die castings | ASTM E505 | Die-casting reference, thickness range, category |
| Digital radiography, aluminum or magnesium die castings | ASTM E2973 | Digital die-casting reference and examination attributes |
These are references to evaluate, not four interchangeable choices. E505 directs digital die-casting examinations to E2973; E155 directs digital aluminum-casting examinations to E2422. Use the applicable edition and the complete procedure with a qualified inspection team.
Turn a drawing zone into an inspectable requirement
For a machined sealing face, decide whether acceptance is about the finished surface, internal indications, leakage under defined conditions, or a combination. Then record the agreement. If machining opens pores on a finished face, see porosity on machined surfaces for how to accept or disposition them. The fields below are a purchasing aid, not a completed inspection specification.
| Field | Entry the project team completes |
|---|---|
| Part and region | Part number, drawing revision, zone ID and boundaries |
| Assessed condition | As-cast, after heat treatment, after machining, or as supplied |
| Discontinuity | Category, and any separate criteria for other indications |
| Inspection | Procedure ID, method and coverage |
| Acceptance | Reference, edition and level, or a defined numerical criterion |
| Sampling | Lot definition, quantity or frequency, selection |
| Evidence | Images or measurements, part ID, interpretation record |
| Failure response | Containment, review authority, disposition |
If a numerical criterion is needed, define what is measured. An area fraction on a stated section, a projected indication and a three-dimensional volume fraction are not the same result.
Drawing-note templates
Copy and complete. Brackets are left for the values your design authority sets; we do not fill them in for you.
ZONE A (sealing face, see view B): RADIOGRAPHIC INSPECTION PER [standard, edition]. ACCEPTANCE: [category] LEVEL [ ] MAX, CONDITION [after machining]. SAMPLING: [ ] PCS PER LOT, LOT = [definition].
ZONE B (remainder): [level / not inspected].
LEAK TEST: [method], [medium] AT [pressure, unit], REJECT ABOVE [leak rate, unit], AFTER [stage], [100% / sampling].
IMPREGNATION: [NOT PERMITTED / PERMITTED PER (spec) WITH REINSPECTION].
Specify leak acceptance separately
A radiographic classification is not a leak-test result. For a pressure boundary, agree the leakage requirement and the procedure that demonstrates it alongside any internal-integrity examination: test medium, pressure, part condition, reject threshold and units, timing and the tested boundary. See helium leak testing for the report fields.
Check the system can make the decision
An inspection requirement must be achievable by the chosen system. ASTM E2422 calls for agreement that the system can detect and classify the required discontinuities; ask how that will be shown for your regions, not only the equipment model. Record who interprets results, how uncertain results escalate, and agree a referee procedure before the first disputed delivery.
Connect sample approval to lot release
Keep the qualification package separate from routine lot records. Agree what happens on a failed result: how material is held, who reviews it, whether more examination is allowed and who signs a concession. If impregnation or repair is proposed, treat it as a documented decision with reinspection. A change of alloy, geometry, tooling or route re-opens the approval.
Squeeze casting and porosity
Squeeze casting solidifies under pressure and suppresses shrinkage and gas porosity, but no process guarantees zero porosity. A squeeze-cast part is accepted on the same zone-based criteria as any other casting. The A356-T6 squeeze casting page shows where the process is evaluated; the casting inspection plan holds the checks together.