What if anything do you use to verify accuracy/repeatability of your cmm?

[terry]

We are researching different ways of verifying the calibration of our CMM’s between calibration cycles. The powers at be do not seem think it is necessary to have an artifact on site to verify the calibration. Does ISO require that you have a means to do they just require you to follow your process what ever it is?

[kmcmm]

ISO only requires to calibrate your machine at established intervals in accordance with your procedures. The only requirement I saw in the ISO9000/2000 standard was that you have to have all your gages calibrated to NIST traceable artifact. There was another post on this, do a search on calibration to find the suggestions.

[Shelley Liebman]

We use what we call a baseline part--this is a part that has the tightest tolerances we generally run here, uses one of our longest tips, and uses 4 different angles of our indexing head.
We have had this part for going on 5 years, and it was also measured by our customer on their Zeiss machine.
Directly after each calibration, we measure this part and keep all of our reports.
Anytime we have a concern that our machine might not be giving us good results, we plop this part up there, and compare the current report to all of our historicaly data.
this has saved us many, many, many times, especially when I get a call at 11:30 pm and the night guy has bumped something and needs to know whether or not he needs to re-calibrate tips.

[Virgil UK]

We don't calibrate between the annual calibration dates, but each new CMM production program has to correlated with another third party program. Gage RR is then ran and the upshoot of this is we measure one part and keep the measured data, like yourself, and call this the "gold standard". This is kept under lock in our stds room.

[John Kingston]

I couldn't answer to the poll, as I do what Shelley does. When Hilton Roberts logs in, he is the Guru of this topic. If you search his posts here and at the other PC-DMIS sites, you will learn quite a bit on the topic.

[dwade]

I have in the past used a Renishaw MCG dumping all into stats and monitor the variation. It really did not check the machines accuracy but gave me valuable data that I could use to tell me when something was not right. I have a TP20 take a dump on me once and caught when my data showed extreme variation one morning.

Right now I am startin to use a master part for this running the same part on all 4 of our CMMs.

[MJBolster]

Just a noob still, but I hope to have several artifacts within the next few years.
From what I've read on the forum it's the cat's meow for verifying accuracy. It
seems weird that the big cmm producers haven't tried to sell us something by now but I wouldn't buy it- unless it was really cool.

Mike

[layout tech]

We have 4 CMM's. I have a "Golden Part" for each CMM. I try to run at least twice monthly. Data is stored in Datapage and Csv files. I compare latest run with all runs since last calibration. Dimension does not have to be in "Spec" on original run just measure the same each time you run it. Our QS9000 Auditor asked me about 2 years ago how I knew my CMM's were running accurately. I told him we had them calibrated annually. Last calibration was 6 month's before. He asked how I knew they were still running accurately. I brought out the "Golden Part" and told what it was and that was the end of that. He was satisfied.

It does not have to be a purchased artifact. I use a production part that has had a movable areas either welded or tapped with a screw to prevent movement or changes. I painted It white and labeled "Golden Part- Qc use only"

[#2#]

Well, I don't verify. I haven't had a problem with it yet.

I like the idea of a "golden part". I may try to find something around here to use. I assume the larger the part the better.

[T Miller]

I run the test block that came with the machine.

[Andrew Gardner]

Every once in a while, if things aren't checking right, I'll use gage blocks to check distances at different probe angles and on different areas of the machine. But, not very often.

[Gregl]

I have a Test part that I use, whenever I get a question about accuracy, I run it and compare it to past runs, take about 10 mins, and cuts thur the bull ****, as production will believe my results after that.

[Jeffrey Lovely]

Any one have a spare test block?

[tking]

Any one have a spare test block?

How about 2, the one for this system is long gone, would be nice for walking through some of the tutorials.

TK

[kevinb]

We're going through a bunch of DPD/MBD stuff with a few of our customers, mostly Boeing, and this subject has recently come up. They want our CMMs verified on a regular schedule with the results stored on file for reference. We ordered a Renishaw gauge that should be here any day now. It'll be nice, as I had a tip get bent just slightly enough to throw out precision, but wasn't visually noticible. It would be nice to run a gauge program and find that out before I measure a part.