sending out Master Sphere for Calibration?

[[Lo...]]

Does anyone else send out their master sphere for calibration? I know this question has came up in the past however I was unable to find anything on it. We have a customer coming in and one of the items they want to review is the past calibrations of our sphere. We have never sent ours out for calibration as I didn't think Zeiss required or recommended it. Calibrations are done yearly through Zeiss on the CMM. We had this come in an audit a couple years ago. I email Zeiss asking about it, but I didn't get a response. I'm not sure what the end result of the audit was as I wasn't involved in those meetings. I'm just looking for how to explain why we are not sending out the sphere. I know its only used to qualify styli and not the machine, but I don't know if that's truly the correct way to explain it. I don't like when things like this come up. How far do you want to take it. Hell, I've heard that someone somewhere was thinking that you send out the styli for calibration yearly...

[[Aa...]]

Yes, this has been an ongoing discussion. The botttom line is that if you get a traceable calibration on your machine from Zeiss, what you're getting is a calibration of the CMM and Ref Sphere as a system. That should suffice. Your traceability does not come through the calibrated size of the Ref Sphere, but rather through a castellated stepper gauge that Zeiss maintains the traceable calibration of.

[[Is...]]

What about a verification, how do you know if the reference sphere is not damaged, if it has wear or the most basic: if is clean?..
I don’t remember the cost of a calibration, but a new sphere is not expensive and comes with Calibration certificate:

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[[Ro...]]

We have 6 cmm's each with their own cal sphere.
The 5 B&S's can share spheres just by telling the machine what sphere its using, but the Zeiss sphere is different, and also at the dual 45º angles.
So we just get the cal house to put a rush on the Zeiss sphere.
We can send it out and get it back in 1 to 2 days.
It's really not a big deal.

[[Aa...]]

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If you send a sphere out for calibration, do they include verification of no damage, or that it is clean? I would think it much more likely that those would be assured as part of the traceable machine calibration from Zeiss. Damage to the sphere or debris would impact the qualified sizes/positions of the styli used in machine calibration, which would make it more difficult for the calibration to meet the machine calibration specs per ISO 10360.

[[Am...]]

I have not sent out our spheres for calibration, I think doing the yearly calibration for the machine counts as it is a whole system and the Tech's use your sphere for their calibration. When you use the sphere you are just qualify he styli and its not a calibration of the machine.

I am curious how many people send them out an if this is something I need to think about starting to do.

[[Is...]]

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With a cleaver implementation the verification of the Reference sphere could be enough

[[Da...]]

All the Zeiss techs I’ve dealt with used their own reference spheres, and they always keep them calibrated. Having a calibrated sphere is important for the traceability of your machine. Since the techs are not leaving their sphere behind, you should take care to keep yours up to date, otherwise there will be no proof to the customer that your probes will be calibrated properly.
When the techs check your machine, they might compare your ref sphere to theirs, but that’s not a traceable calibration. And yes, the spheres will change very slightly overtime, so expect tiny differences after calibration. The more precise your machine is, the more important is it to know the diameter and form error of your reference sphere.