In house CMM calibration

[[Ro...]]

We get our CMM calibrated from Zeiss yearly, but one of engineers wants us to start calibrating more often in house. Does anybody do this and if so how and with what. Gage department suggested a gage block but how would you clamp it. Thanks in advance

[[Th...]]

Do you mean probes calibration or the actual CMM axes? We calibrate all probes weekly but I think only Zeiss calibration tech can do the full CMM calibration.

[[La...]]

Imagine having someone come in with incredibly accurate equipment and calibrate your machine and then Engineering suggests to calibrate 'with a gage block'. Geez.

Consider maybe validating your CMM results with a certified artifact and program, such as this:

https://shop.metrology.zeiss.com/INTERS ... m:artifact

[[Ro...]]

Thinh,
The actual CMM axes. (x-y-z) per engineering.

[[Ro...]]

Even if you use a gage block, ball bar, artifact, etc to measure on the machine, you're only validating the machine accuracy/calibration.

Actual calibration means you'd need to have the ability to adjust the comp/error map that controls the measuring volume of the machine based on the measuring data you get from those artifacts, as well as all the physical adjustments to the machine itself.

[[Ün...]]

Remember that the device has been serviced and there may be parts that are worn or need replacing depending on use.

[[Ow...]]

If they’re just wanting to ensure the CMM is repeating as it should, you might just need a known ‘Master’ part that covers the majority of the axis’s, size and form of the features/characteristics commonly checked on the CMM. For instance, maybe keep the largest or average size part you make or check routinely in the CMM room and check it before calibration, after calibration (to see changes, if any) and after a significant crash.

You have to pay extra to have a calibration that records the CMM “as found” prior to calibration but, maybe that’s enough to satisfy their curiosity or justify the need to have it calibrated more often internally or externally.

Attached is good article covering several methods, material, and practices.

CMM verification and Calibration NPL.pdf

[[Ri...]]

I've created two programs.
Two different sized Triangle measurements. It utilizes three Tooling balls.
They are placed, in a triangle configuration. One LARGE triangle and one SMALL triangle.
The three tooling balls are used in three True Positions set for X,Y,Z axis (Sphere).
They have a tolerance of 0.0003" (Inch) per True Position.
There should be Zero OOT conditions.
Its simple, its quick, and its effective.
You will want an Excel file to collect data all year long (Or use something like ProLink).

Week 1
Set up the LARGE triangle relative to the Z axis. Run the Large Z axis (a random name) program.
Week 2
Set up the LARGE triangle relative to the X axis. Run the Large X axis (a random name) program..
Week 3
Set up the LARGE triangle relative to the Y axis. Run the Large Y axis (a random name) program.
Week 4
Set up the SMALL triangle relative to the Z axis. Run the Small Z axis (a random name) program.
Week 5
Set up the SMALL triangle relative to the X axis. Run the Small X axis (a random name) program.
Week 6
Set up the SMALL triangle relative to the Y axis. Run the Small Y axis (a random name) program.
Week 7
Start the process again, move all fixturing to some random place on the CMM (This is important).

[[Je...]]

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I completely agree with you, Laura. The Zeiss hardware technicians are trained to perform calibration per ISO 10360 with NIST traceable step gauges.

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Jeff Frodermann
Meier Tool & Engineering
Anoka, Minnesota.
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