Qualification after drives off

[[Pa...]]

Accura and Accura2, VAST Gold in each

My company requires qualification of all styli after drives off, whether it happened due to a collision or a holiday weekend shutdown.  I've felt for a long time that this is unnecessary, particularly in the intentional shutdown scenario. What would change about a stylus or a stylus system (relative to the Master Stylus) during a shutdown?  I've got a couple machines; each has a rack with 21 systems.  They're all very different from one another, meaning I need to use 3 different sphere sizes in a total of 7 positions.  A full qualification of both machines takes just under 3 hours.  This past holiday the pain of lost hours was great enough I think I'm poised to make a change here.

I'd happily verify a couple and get back to work in 15 minutes if there were no findings.

Google's AI bot says there's no reason.  I believe him, but I don't trust him 😉

What do you guys think?

[[Ma...]]

I would calibrate right after crash just that probe system and then regularly, depending on your usage.

You can get into situation, where you have a collision which is not a collision, just a probe which ran into a void.
There is no need to do such calibration after drives are off - they can shut down to conserve air consumption every 15 minutes of inactivity - that would be hilarious to do calibration in this case.

I am running calibration program, which measure before calibration and then after calibration - this can tell you if you have a problem with specific probe ( lose screw and so on )

[[Da...]]

I'm using quite a number of different probe systems. If I did a complete re-qualification every day, I wouldn't do much else. So, I have to be smart about it.

I want to make sure of two things:

1. The probe systems measures the correct diameter. Instead of a whole calibration routine, I run a small routine that measures the reference sphere. That way I can make sure the measured diameter is within limits.
2. If I use multiple probes in one program, I re-calibrate those (and only those) ahead of my first run of the day.

Usually, I check the probes more often than I calibrate them. It's faster and gives you a feeling of security, because I had calibrations that I had to repeat, because the positions among the probe systems were not satisfyingly precise.

Edited 12 hours ago

[[Pa...]]

So far, just as I thought, except I didn't know about the drives shut down after 15 minutes.  That's a new one on me.  Is there a way I can validate this and show it to the people requiring this needless exercise?

Yes, qualification after collision is certainly necessary.

[[No...]]

They only shut down if the CMM is equipped with AirSaver. Then you have a small application on the PC where you can set the timeout and also shut them off manually. The default is 15 minutes.

This thread has a screenshot of the app:

https://qualityforum.zeiss.com/topic/18466-air-saver-help/

[[Je...]]

I would recommend you ask for proof of the claim that verification is needed after CMM shutdown.  In most situations, it is not risk-mitigating or necessary to requalify all styli after a power shutdown.