Probe calibrations and documenting them

[[Tr...]]

I thought surely this topic had been discussed many times before, so I spent a lot of time searching through previous posts. However, I did not find the information for which I sought. Therefore, I'm here with questions about probe calibration frequency and the documentation thereof. My company operates under the ISO 9001:2015 standard. We have two Zeiss CMMs. Both are older but well-maintained. One is a Contura G2 with a VAST XT scanning probe head. The other machine is a Prismo with the VAST Gold probe head. Neither our gage calibration program nor our quality system specifies a certain calibration frequency for CMM probes, but we are considering this addition. Currently, we calibrate the probes every two to three weeks, more often if we feel it is needed. These CMMs do not run constantly. They are used most days but not every day and only occasionally on multiple-piece runs. I use a probe calibration program and after I run it, I save the results in .pdf format. We've been doing things this way for a very long time, but it seems logical that we should specify the frequency and method of documentation somewhere. However, I don't want to back myself into a corner if it isn't necessary. How are you dealing with these issues?

[[Da...]]

Be careful what you put in writing. The whole basis of ISO 9001 is that you do what you state in your written procedures. When you get incredibly detailed in your written procedures it opens you up to higher chances of the auditor making more findings during their audit. The more basic the procedure the better, essentially. Records of the yearly machine calibration and preventive maintenance should be enough depending on how detailed your procedures are. Just make sure that what is actually being done and what your procedures state match. If they don't, determine whether the written and/or actual procedures should be revised.
I used to work as a quality manager and had to manage, ISO 9001, ISO 13485, and FDA 21 CFR 820 so having simple but complete written procedures that matched the actual processes being performed were key.

[[Tr...]]

Thanks, Dave. That's what my intentions are here. We have a few customers who tend to expect more than the ISO standard requires at times, so we'll need to find a happy place in there somewhere. 😎 My first thought is to avoid obligating myself unnecessarily.

[[Jo...]]

I like Dave's advice. It can be a slippery slope. So now you state procedure is to qualify probes once weekly, then do you state acceptance criteria ? corrective action if fail etc.. This also completely ignores the machine volume check that used to be a ball bar program or golden part. Auditors tend to drill down on questions and the less the better.

[[Tr...]]

There's a minimum allowable sigma that Calypso will accept (I can't remember what it is). That's good enough for the acceptance criteria in my book. I'm definitely going to keep it as simple as possible. I have probe calibration records that go back 8-10 years and I may have shown them to an auditor from our registrar once or twice during that time period. But, I can envision an over-zealous auditor from one of our customers asking about it. I think some documented regular schedule of probe calibration with acceptable results would keep an auditor from digging any deeper.

[[DW...]]

According to page 21 of the Zeiss Sensor Cookbook -

Notice:
1. Regular qualification of all stylus systems (once per shift and at least once per week) is recommended.
2. After collisions or changes to the stylus systems (e.g. replacement of a stylus), qualification is necessary again.

I would add - Qualify the stylus system any time a measurement comes into question. On more than one occasion, I have had an operator question the CMM results after getting a report and after much back and forth and rerunning of parts find out the stylus was the culprit.