PC Inspect per control plan
Inspect per control plan · Inspección y ensayos · ISO 1101 + ASME Y14.5
Example in plan
How to interpret it
On the drawing, “Inspect per control plan PC-045 rev. B” states a inspect per control plan requirement.
What controls
Reference from the drawing to an external document, the control plan, which defines for each characteristic what is measured, with which instrument, how often, by whom and where it is recorded. The drawing says what the part must meet; the control plan says how that is demonstrated. It is a process instruction, and without the control plan in hand the note cannot be executed: on its own it does not say how many parts must be measured.
How to verify
Whatever the plan specifies, with calibrated instruments identified in the record. The plan usually distinguishes standard, key and critical characteristics, with different frequencies and methods for each level. Besides the result, the date, shift and operator are recorded, because traceability of who measured and when is part of the control.
Common mistakes when interpreting it
- Working from the drawing only and assuming the inspection frequency.
- Using a control plan from an earlier revision than the current drawing.
- Swapping the specified instrument for another without checking whether it has sufficient resolution and uncertainty for that tolerance.
How to get it in the workshop / if it comes out of tolerance
Start the job by opening the control plan alongside the drawing, and check that the plan revision matches the drawing revision: that is the most common mismatch. From it you get the frequency (every part, every hour, every lot), the instrument and the record format. If the plan calls for a specific instrument, do not substitute another “equivalent” one without approval: measurement capability is part of the control.
If the control plan asks for something impossible in practice (a frequency incompatible with cycle time, or an instrument the shop does not have), escalate it and get the plan changed; do not solve it by skipping it. If the drawing and the plan disagree on a tolerance, the drawing governs and the plan must be corrected. And if a characteristic on the drawing does not appear in the plan, raise it: it is probably an omission in the document.
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