TL;DR
Probe qualification failure means the CMM cannot establish a reliable stylus reference and should not be used for inspection until resolved. Clean the reference sphere and inspect the stylus before re-qualifying.
What you might see
- qualification routine aborts with a probe error
- form error on the reference sphere exceeds the acceptance tolerance
- qualification results inconsistent between runs
- stylus shows visible contamination or damage
Likely causes
Reference sphere contaminated with oil film, fingerprints, or part dust
Stylus tip chipped or scratched from contact with a part edge
Probe head or extension not fully seated and locked in the rack
Thermal gradient across the CMM volume from nearby heat sources
Required tools
- Lint-free cloths and isopropyl alcohol
- Cotton gloves for reference sphere handling
- Magnification loupe
- Replacement stylus (matching material and length)
Safety first
- Do not apply force to the CMM stylus or probe head. CMMs are precision instruments and physical contact beyond gentle cleaning can shift the calibration.
- Ensure the CMM room HVAC is stable before qualification. Drafts or temperature changes during qualification will produce unreliable results.
Procedure
- 1
Clean the reference sphere with a clean lint-free cloth and isopropyl alcohol. Do not use abrasive cleaners. Handle the sphere with clean cotton gloves after cleaning.[1]
- 2
Inspect the ruby stylus ball under a magnification loupe for chips, flat spots, or contamination. Replace any damaged stylus.
- 3
Verify the probe head is fully seated in the probe changer rack and the kinematic coupling is clean and free of debris.[1]
- 4
Check the CMM room temperature. Zeiss CMMs require a stable temperature between 18 and 22 C with less than 1 C per hour variation. If temperature is outside range, allow stabilization before qualifying.
- 5
Re-run the probe qualification routine. If the result passes, document the new qualification values.
- 6
If qualification still fails, substitute a known-good stylus and re-test. If the known-good stylus passes, the original stylus is defective.
- 7
If qualification fails with multiple styli, suspect the probe head. Contact Zeiss service for probe head inspection.
Sources
Zeiss Zeiss CONTURA / PRISMO Coordinate Measuring Machine (CMM) general technical documentation, Zeiss
Zeiss CONTURA / PRISMO CMM operator and qualification documentation (general)
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