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Aubrey Kagan

Calibration, Part 1

Aubrey Kagan
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antedeluvian
antedeluvian
10/14/2013 9:52:28 AM
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Re: Calibration standards and calibrators
eafpres

Typically involves multiple operators making the same measurement multiple times and assessing how much variation comes from the measurement system and how much comes from the operators.  Those uncertainties then figure into your analysis of actual measurements in terms of confidence interval.

Interesting. We are a small company and we really don't have the resources to tackle this approach. Firstly we try to design the test so that no technical knowledge is required although that is not always possible. Where the test is software based I always create a table of parameters that can be adjusted. Often the test is built around prototype runs and so we don't really have an idea of where the variations will come from especially after we outsource production/test to the Far East.

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eafpres1
eafpres1
10/14/2013 8:38:30 AM
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Re: Calibration standards and calibrators
Hi Aubrey--it should be gauge R&R, although it is interesting how many references use gage R&R.  Anyway, it is the process of testing the repeatability & reproducibility of the measurement system.  Typically involves multiple operators making the same measurement multiple times and assessing how much variation comes from the measurement system and how much comes from the operators.  Those uncertainties then figure into your analysis of actual measurements in terms of confidence interval.

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antedeluvian
antedeluvian
10/11/2013 4:25:50 PM
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Re: Calibration standards and calibrators
eafpres

 One thing you did not mention is a gage R&R on your testers.

 

It's a Friday afternoon (of a long weekend here in Canada) and my brain is possibly a bit slow. I don't believe I am familiar with the term "gage R&R" and "R&R" before a long weekend takes on a different meaning. Could you elaborate please?

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eafpres1
eafpres1
10/11/2013 4:21:35 PM
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Re: Calibration standards and calibrators
Thanks, Aubrey.  Good article, covers everything I have been through on the automotive side.  One thing you did not mention is a gage R&R on your testers.  Do you routinely do that on new test setups?

I also think that for complex test setups you pretty much have to have golden parts, and backups for those.

Your idea of known bad parts is interesting.  I don't think we ever went that route that I can recall.  Doing FMEA on the test setup is also an interesting idea.

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antedeluvian
antedeluvian
10/11/2013 3:59:28 PM
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Re: Calibration standards and calibrators
eafpres

I promised there would be a blog on verifying that your test equipment is working. Here it is: Testing Your Test Equipment

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B_Albing
B_Albing
9/22/2013 7:53:50 PM
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Re: Calibration standards and calibrators
@Scott - that, and 3 barleycorn kernals; and the distance from the king's elbow to to tip of his middle finger. That should cover it.

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B_Albing
B_Albing
9/22/2013 7:51:52 PM
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Re: Calibration standards and calibrators
@eafpres - you're making my head spin....

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B_Albing
B_Albing
9/22/2013 7:48:04 PM
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Re: Calibration standards and calibrators
@eafpres - to just that one point you made - yes! Check you equipment and its calibration before you start gathering data/running a test. I recall overlooking that important step as a young whippersnapper engineer. And wasting my time on a test (and the time of the engineer in charge of the project).

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B_Albing
B_Albing
9/22/2013 7:44:23 PM
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Re: Wisest Thing Written
@Scott - always good to keep from getting Aubrey riled up (he knows where you live). So, good that you agree with his approach.

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RedDerek
RedDerek
9/16/2013 12:52:07 AM
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Master
Re: Wisest Thing Written
But is a straight line straight on a sphere? Is it straight on a CRT? (OK, a bit of aged humor)

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