Calibration shows the instrument was good on one day. Interim checks show it stayed good, and they shrink the window of an impact assessment from months to days.
| Instrument | Interim check we use | How often | Recorded where |
|---|---|---|---|
| Calipers and micrometers | Zero check; one gauge block near the most-used size | Start of shift; weekly block check | Check sheet at the station |
| Height gauges | A gauge block near the most-used height | Daily | Lab start-up sheet |
| Bore gauges | Set and check on the ring master | Before each use | Not recorded unless the setting is off |
| CMM | Probe qualification; a reference artifact measured and charted | Each start-up; weekly | CMM log; artifact chart |
| Torque tools | Check on a torque analyzer | Before critical work | Torque check log |
A failed interim check is treated like an out-of-tolerance calibration: stop using the instrument, quarantine it, and open an assessment from the last good check. This is where interim checks pay for themselves: the window is one day, not six months.
Handling, storage and conditions
- Instruments are stored in their cases or protected racks, away from coolant and chips, and never loose in a drawer with other tools.
- Dropped instruments go to the quarantine box until checked, whatever they read afterward.
- Measurements near the limit of a tight tolerance are made with the part and the gauge at the same temperature, near the reference temperature; parts fresh from the machine are allowed to soak.
- Adjustable instruments are protected from adjustment that would invalidate the setting (seals or tamper-evident labels where adjustment is possible).
Training the people who measure
Most measurement errors are made by people using good instruments in different ways. Competence for measuring is part of each role's competence (7.2), and it is cheap to build:
| Role | What they need to be able to do | How we show it |
|---|---|---|
| Operators who self-inspect | Choose the right instrument; zero and check it; measure the feature where the drawing means; record the instrument ID | Sign-off by an inspector on three real parts; included in gauge studies |
| Inspectors | All of the above, plus reading the drawing's datums, temperature effects, attribute gauges, and when to stop a gauge | Practical test on boundary parts; attribute agreement studies |
| Calibration coordinator | Reading a certificate; checking traceability and uncertainty; the out-of-tolerance path | Supervised review of the first ten certificates |
| Quality engineers | Impact assessments; gauge study design and interpretation; uncertainty basics | A worked assessment and study reviewed by the quality manager |
| CMM programmers | Datum setup, program verification, change control | A verified program reviewed by a second programmer |
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A management aid, not certification or a registrar audit. Using it does not by itself show conformity to AS9100D or any other standard, and your customers' requirements may add to it.
Clause numbers refer to AS9100D (SAE AS9100 Rev D) unless another document is named. The standards' text is not reproduced here: use your own licensed copy.
Aegis Insights are our own guidance, labeled wherever they appear: how we approach this work, not a requirement of any standard or customer.