Accept, rework or reject: the buyer's view
This guide is for incoming inspection and drawing notes, not for foundry process control. For each defect it gives how it is found, how to write the acceptance limit on the drawing, and what is normally done with a part that fails. The limits themselves are yours to set from the part's function; we do not prefill them. Most disputes start because both sides use one word for two defects, so agree the vocabulary first.
| Defect | Found by | Drawing limit | Usual disposition |
|---|---|---|---|
| Gas porosity | X-ray, sectioning, machined-face inspection | Reference grade per zone; visible pores on machined faces by size and count | Reject in sealing zones; accept elsewhere within limit |
| Shrinkage | X-ray, leak test, sectioning | Reference grade per zone, separate from gas porosity | Reject in load or sealing zones; route review if repeated |
| Cold shut / cold flakes | Visual, dye penetrant, leak test | Not permitted on sealing faces and load paths | Reject on functional surfaces |
| Blisters | Visual, after heat treatment or coating | Size and count per surface class; none on sealing faces | Reject on functional surfaces; may rework cosmetic |
| Cracks and hot tears | Visual, dye penetrant, X-ray | Not permitted | Reject; no weld repair unless agreed in writing |
| Flash | Visual, dimensional | Maximum residual flash height at parting line and holes | Rework by trimming or deburring |
| Warpage | CMM, flatness on a surface plate | Flatness or profile tolerance, in the delivered condition | Straighten if permitted; else reject |
| Ejector-pin marks | Visual, dimensional | Permitted locations and maximum height or depth | Accept within limit; machine if on a functional face |
| Misruns | Visual, dimensional | Not permitted | Reject |
| Inclusions | X-ray, machined faces | Reference grade for foreign material per zone | Reject where exposed by machining on functional faces |
| Soldering | Visual | Surface class limits | Rework cosmetic; reject on functional faces |
Porosity
Gas porosity shows as rounded, smooth-walled voids on a radiograph or a machined face. Write the limit as a reference grade per zone (ASTM E505 for die castings, E155 or E2422 for other castings), plus a visual limit for pores exposed on machined faces: maximum size, count per area and minimum spacing. A pore on a sealing face is judged by the leak test, not by appearance alone.
Shrinkage
Shrinkage voids are ragged and clustered, in thick sections and at junctions. Keep its grade separate from gas porosity on the drawing; they have different causes and different consequences. Shrinkage in a tapped boss often appears only after machining or as a leak. Repeated shrinkage in one zone is a route question: a thicker section may need squeeze casting.
Cold shut and cold flakes
A cold shut is a seam where two metal fronts met without fusing; cold flakes are pre-solidified skins folded into the casting. Both are planes of weakness and, on a pressure part, leak paths. Write "no cold shuts on surfaces A, B, C" rather than a size; detection is visual with dye penetrant where the surface is critical.
Blisters
Blisters are raised bubbles of gas near the surface that expand when the casting is heated: during T6 solution treatment, powder curing or in service. A die casting that is blister-free as cast can blister in the oven, which is why conventional die castings are usually not T6 treated. State the surface classes, the maximum blister size and whether the check is after heat treatment or coating.
Cracks and hot tears
Cracks are normally not permitted anywhere. Specify the detection method for critical regions (visual, dye penetrant, X-ray) and whether weld repair is prohibited; if the drawing is silent, ask us to treat it as prohibited.
Flash
Flash is a thin fin at the parting line, slides or ejector holes. It is a rework item. Specify the maximum residual height after trimming and the edges where a sharp edge or burr is not acceptable.
Warpage
Warpage is distortion from uneven cooling, ejection or heat treatment. Give flatness or profile tolerances in the delivered condition and say whether straightening is permitted. Measure from the agreed datums; warpage measured on a different set of datums is a different result.
Ejector-pin marks
Ejector pins leave round marks, raised or recessed. On the drawing, mark where marks are permitted and their maximum height or depth; on sealing or mating faces, require them to be machined off or relocated during tool design.
Misruns, inclusions and soldering
Misruns (unfilled sections) are rejected. Inclusions are graded with the foreign-material category of the radiographic reference and judged on machined faces where they are exposed. Soldering leaves torn, rough patches where metal stuck to the die; it is a surface-class item. Sand holes, scabbing and burn-on come from sand moulds and do not occur in die or squeeze castings; if you see them, check the part's origin.
When the result is disputed
- Name the defect from the shared table before arguing the limit
- Check the zone, view and condition the requirement refers to
- Re-measure from the agreed datums with the agreed method
- Keep failed parts and images segregated for joint review
- Record any concession as an approval, not a silent change