What is the difference between self-inspection and final inspection?

Self-inspection is done by the operator during production, to correct drift at once. Final inspection, often by the quality department, checks the finished part before delivery.

How often should parts be checked?

There is no single rule. The first part after a set-up is always checked, then at a frequency based on risk (tool wear, tight dimension, defect history), for example one part in ten.

Should every dimension on the drawing be checked?

No. Self-inspection covers the characteristics produced at the operation and those likely to drift. Checking every dimension is the job of the first article inspection (FAI) report.

Operator inspection sheet: build it from the drawing

Updated October 14, 2026

The operator inspection sheet (self-inspection plan) tells the machinist what to measure on the part, with which gauge, how often and between which limits. Done well, it catches drift before it turns into scrap.

What an inspection sheet contains

Part number, drawing revision and the operation concerned.
The characteristics to check, identified by their balloon number on the drawing.
For each one: nominal size, min and max.
The measuring instrument: calliper, micrometer, plug gauge, thread ring gauge…
The frequency: first part, one part in n, at every tool change.
Boxes to record measurements and what to do if a value is out of tolerance.

Step-by-step method

Start from the ballooned drawing: every characteristic already has a number.
Keep the characteristics produced at the operation, critical or hard-to-hold ones first.
Work out the min and max of each dimension, including general tolerances (ISO 2768) and fits (ISO 286).
Choose the instrument: its resolution should be about ten times finer than the tolerance band.
Set the frequency by risk: more often for a critical dimension or a fast-wearing tool.
Have the sheet approved, then post it at the machine with the ballooned drawing.

Common mistakes

Copying dimensions by hand from the drawing: a wrong min or max goes unnoticed.
Too many characteristics: the operator no longer has time to measure everything and the sheet is left blank.
An unsuitable instrument, such as a calliper for a ±0.01 mm tolerance.
A sheet that is not updated when the drawing revision changes.

Generate the sheet automatically

Bulleur PARFAIT produces the self-inspection plan as an Excel file together with the ballooned drawing: balloon numbers, dimensions, calculated min and max, ready to print. All that is left is to choose gauges and frequencies.

Frequently asked questions

What is the difference between self-inspection and final inspection?: Self-inspection is done by the operator during production, to correct drift at once. Final inspection, often by the quality department, checks the finished part before delivery.
How often should parts be checked?: There is no single rule. The first part after a set-up is always checked, then at a frequency based on risk (tool wear, tight dimension, defect history), for example one part in ten.
Should every dimension on the drawing be checked?: No. Self-inspection covers the characteristics produced at the operation and those likely to drift. Checking every dimension is the job of the first article inspection (FAI) report.