100% 100% inspection
100% inspection · Inspección y ensayos · ISO 1101 + ASME Y14.5
Example in plan
How to interpret it
On the drawing, “Inspect 100% of critical dimensions per control plan PC-012” states a 100% inspection requirement.
What controls
Instruction that the specified characteristic be verified on every single part in the lot, with no sampling. It is a requirement on how the characteristic is controlled, not on what the part has to meet: the acceptance criterion is still the dimension and its tolerance. It can apply to a single characteristic on the drawing (the most common case) or to a defined set; if it does not say which ones, the note is ambiguous and must be clarified before releasing production.
How to verify
The instrument is set by the control plan, not by this note; what this note sets is the frequency. In practice, 100% inspection is done with functional gauges, dedicated inspection fixtures or automated in-line measurement, because they are the only methods compatible with cycle time. Whatever the method, it must be calibrated and its measurement capability must be adequate for the tolerance it checks: an instrument with too much uncertainty for that tolerance lets bad parts through no matter how many parts are measured.
Common mistakes when interpreting it
- Taking it to mean every dimension on the drawing must be measured on every part: it applies to the specified characteristics.
- Replacing it with sampling when production is under pressure: inspection frequency is a contractual requirement, not a recommendation.
- Doing 100% inspection without recording results, which leaves no evidence that it was done.
How to get it in the workshop / if it comes out of tolerance
It has a direct impact on cycle time and cost per part, so plan the inspection method: a go/no-go gauge or a dedicated fixture handles 100% inspection in seconds, whereas measuring each part with a micrometer can double the operation time. Have the record sheet ready before you start: 100% inspection with no recorded evidence is worthless when the customer asks for traceability.
If 100% inspection is eating into cycle time, the way forward is to change the inspection method (a gauge or dedicated fixture instead of general-purpose measurement), not to reduce the frequency on your own. If repeated rejects appear, the 100% check is acting as a filter when the problem lies in the process: the process has to be stabilized, because inspection does not improve quality, it only sorts it. And if a bad part is found, review what happened with the earlier parts already delivered.
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