Metrology Quality Rules Tur-Tar

In this episode, we are going to talk about some quality rules that are often used in calibration to determine the acceptability of measurement standards or systems. For example, in a past episode of the metrology training lab we discussed the calibration of micrometers and recommended Grade 0 gage blocks saying that they were sufficiently accurate.
What do we mean by sufficiently accurate? What calculations can you make to justify the selection of measurement standards or your calibration providers based on quality.
We are going to discuss two of these common ratios, one being the test accuracy ratio or TAR and the other being the test uncertainty ratio or TUR. Sometimes called the TAR and TUR.
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[@465maltbie]

I must have missed something but where did the 10 min number come from? How did you determine that the zero gage block was within that calculation? I listened twice and I think I still must have missed it.

[@dr.jimsalsbury695]

The ±10 µin uncertainty was taken from an example in the ASME B89.1.13 standard. How to estimate uncertainty is beyond the scope of this video, so we just borrowed the value from a recognized source. In order to do TUR calculations, you first need uncertainty. To see how the 10 µin uncertainty was determined, please check out ASME B89.1.13 (in the appendix on measurement uncertainty). Also, see www.mitutoyo.com/mitutoyo-on-demand/decision-rules-tar-and-tur/

[@465maltbie]

Thank you I heard that in the video but I guess I just didnt understand it. I will check out the links. Charles

[@tropicalcasa]

Excellent presentation and use of the correct terms of TUR and TAR. I like that presenter was very objective and professional in terms of the application of the calibrated instrument.

[@dr.jimsalsbury695]

It is comments like this that motivates us to make more videos. Thank you so much.

[@gajanank3812]

Nice

[@israelbarrios1549]

excellent

[@xddrek]

v.good. I couldn't understand that that some accreditation body giving accreditation of a lab have their CMC +-2% in pressure measurement. Then what is the use of that lab. whether ILAC have any guideline on that?

[@davidbeier1562]

When calculating the TUR for determining a ratio 4 to 1, is the resolution of the TI included (0.6R) or repeatability? A 4 to 1 will never be achieved using that method. I was at a NCSL seminar in Cleveland and the presenters said that the resolution should be included. I recall Jim standing up and say it shouldn't only for your CMC but not when determining a TUR. Certain accredited bodies require the resolution be used to calculate TUR. I have seen companies state a process TUR which doen't include any variables resolution or repeatability . What is it and where is the guidance document to prove it one way or another.

[@boatmanfall3n]

JCGM 100:2008 or otherwise known as "The GUM" (Guide to the expression of uncertainty in measurement)