Coordinate Measuring Machine Uncertainty - Research Resolving CMM Uncertainties

[Marc]

Guidance on interpretation and implementation Measurement Research Resolving CMM Uncertainties http://www.sme.org/cgi-bin/get-press...c&2&20002798&& DALLAS, TX (7/10/2000).

The International Standards Organization is in the final phases of re-writing its 9000 series quality standard that will include a requirement that manufacturers determine the level of uncertainty they have when measuring the toleranced features of their parts and products. Coordinate measuring machines (CMMs) are capable of precisely measuring features, but there have always been difficulties in assessing the accuracy of those measurements. A new company, called MetroSage, has been formed in California by some of the nation's leading metrology and software researchers to address this tricky, technical challenge. The company is a result of a decade-long research commitment made by the Consortium for Advancement Manufacturing--International (CAM-I). Work conducted by the National Institute of Standards

[Steven Truchon]

Speaking of CMM Uncertainty, I have harbored this possibility for years so I thought I'd toss it out for scrutiny.

Part tolerance= hole location = cylindrical postional tolerance of .002 RFS.

Machine linear accuracy (XY) = +/-.0002
Touch probe accuracy = .0001

Total machine meas error = .0003
Calculated cylindrically (true position formula)= an error zone of .00085 diameter

Using the 10:1 rule of accuracy to tolerance would this CMM configuration only be able to measure Cylindrical Positional Tolerance of .0085 diameter or larger??

Whaddya think?

Steve

[Timmer]

Hi all...this is a quick and vague question thats been passed down to me from about 4 others....understand thats its Friday 10 minutes before I take off for a few days as well! Anyway, I was asked if there was a way that we can determine our uncertainty on the CMM's that we use throughout the plant. I'll provide more infor if necessary, but for now thats all I have! Tim

[Marc]

Sorry that last post was missed.

But - There is a good article at:

http://www.qualitymag.com/CDA/Articl...121654,00.html

I'm not sure about Quality Magazine links or how quickly they expire (if they do).

Software and calculations are a recognized contributor in the uncertainty of the measured characteristic. Source: ISO/TS 14253-2:1999(E)

[bmccabe]

I’m amazed at how often the Cove’s archives have helped me, and also how often the utterly unknown standard proves to be the missing piece of the puzzle. We waist so much time re-inventing-the-wheel, I always pleased to find my work has already been done.

Mark, what is your opinion of ISO 14253 and ISO/CD TS 15530?
Are they worth the price?
We have some grant money to spend; is there any training available for either of these?

[cbearden]

I've always heard you can be as high as 4:1 and be ok.....So the answer to your question, Stephen.....is "Yes" you can.

'course I could be wrong.....

ZeissUser