Probe requalification intervals

[[Jo...]]

I've had some heated discussions on this topic, and have been given conflicting information from people at Zeiss as to what their recommendations are.
In this poll, pretend that you are running parts that have very tight tolerances on a variety of characteristics and complex datum structures, they aren't just door wedges.

A Zeiss rep. has recommended at one point that Zeiss's official guidance is that re-qualifications should be done daily to account for environmental variations. At another point I was told that there is no official recommendation at all and that it's essentially Chef's Choice.

Personally, I try to do a geometry re-qualification on most of my most commonly-used probes once a week but have been caught in a few rare instances where I had a part come out bad, re-qualified the probe (with a day or two interval between qualifications) and it was enough to "flip it" to green. We are talking on the micron level though in my case.

So do you all "schedule" yours at regular intervals? What's your jam?

[[Jo...]]

Daily with sigma limits, It is easier than convincing operators that probes must be clean..

[[Mi...]]

We have a unique situation where we have a very large number of CMMs, and they run in a production environment like very expensive gauges....every program is available in 2 or more places.

"as needed" generally means when the machinists get a result they don't believe or when they run the part on a different CMM and get poor correlation, but all of our lab ones have a weekly requirement for the bread and butter probe systems with the limit set to 15 days so the calibration can be missed 1 week.

Some production CMMs get calibrated a few times a week, other's have gone 6 months without presenting a problem that needed calibration.

With more techs I would like to have a weekly calibration for all machines but it would be a full time job just to do that.

[[Cl...]]

In addition to qualifying every Monday morning, we measure (daily) several master Parts.
If any of the master parts dimensions deviate more than 10% of the tolerance from the master
report results, we re-qualify the stylus used for that particular result.

[[Ke...]]

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"Daily to account for environmental factors" is a terrible blanket statement... it really depends on what those environmental factors are. The temperature deviation may be more pronounced between (for example) 7am vs 3pm, rather than a simple "day-to-day" variation. Unfortunately, there is no one size fits all answer.

[[Ri...]]

When I worked in manufacturing, we qualified every shift, and any time there were concerns.

It's all about risk. How long can you "afford" to go between a qualification.

As for the environment, that's a huge factor, temperature swings, but also usage/abuse. Crashes happen, and it's better to not just assume that the data is fine.

You should also re-home your machine ever so often as well.

[[Jo...]]

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Re-homing the machines honestly has not been a thought that had crossed my mind - ironically, because as a machinist that was a thing I would do daily. I could look it up but is there an easy way to do this without a complete shutdown/restart of the machine? I often have many coals in the fire (read: a bunch of programs always open for floor checks) and would prefer to not have to restart frequently if I don't have to.

[[Ju...]]

Shift+Lower Return, then F12 homes the Contura that I operate.

[[To...]]

How many of you run stylus verifications as opposed to stylus qualifications? The downside to always doing a stylus qualification is that you wipe out any evidence of the stylus's integrity. Whereas, a stylus verification shows me the condition of the stylus, good or bad, which then allows me to say that everything inspected since the previous verification has been checked with a good stylus or a bad one.

[[Jo...]]

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I'm heading to the Google machine about this topic. It's not something I'd considered much before.

[[To...]]

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Falls in line with the same thinking of using a "gold master" part to verify your machine between calibrations, especially after a crash, or serious bump...

[[Cl...]]

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Thats why we do the daily master part measurements.

[[Ro...]]

For TX and XTR i say weekly is fine.
For XXT i would say daily.

This is based solely on personal experience and how many times ive had to fix questionable results by requalifying.

[[Da...]]

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And also Re-Link or Calypso restart after, so that it actually pulls the new homing position of a controller.

[[Jo...]]

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Are your master parts inspected and verified by a third party or anything, or are they simply known to be a given size after being checked with a very high level of accuracy in-house? E.g., your shop produces a part is made with precision-ground features and then verified with something like a very high accuracy laser mic and that becomes a "master part".

It's always interesting, and informative for myself, to learn about how other facilities manage and maintain the CMM arm of their Quality departments.

[[Cl...]]

Very simply the master parts are the high volume, tight tolerance production parts measured with the CMM they are normally ran on during production, and the report filed for future reference. This is also done after the CMM's annual calibration. Every day we re-run these master parts and compare them to that initial report. If any of the results vary more than 10% of their tolerance, we re-qualify, and inspect for damage the suspect styli. We run production 24/6 and have found that through analyzing the daily master part results, a weekly stylus qualification is sufficient.

[[Ri...]]

I tend to do a weekly qualification, after running a capability study of the qualifications for at least 20 days straight.
If a measurement issue arises, I then check against an artifact for the affected stylus after cleaning the stylus.
If the artifact is accepted, then the part is recleaned and re-ran as is.

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[[Ri...]]

I feel better after reading a lot of these responses.

I once went to a location where they hadn't qualified a stylus in over a year.

[[Da...]]

We cal all probes on Monday. But after a bump that causes the machine to stop, I require everyone here to re-cal that probe. We run very close tolerances and if a part uses more than one probe, or a Tee shaped probe the "bump" could shift the probe location. I worry about that much more than actual damage to the ball. (unless it was a major strike).