Viscometer Gage R&R (GR&R) Questions

[Geoff Withnell]

I would strongly recommend "Evaluating the Measurement Process" by Donald Wheeler. I had a similar problem in measurement some years ago, and his work was very useful in understanding how to evaluate our measurements. It is not available from Quality Press, but I believe Amazon can get it.

Geoff Withnell

[jmarcus - 2008]

Thank you all for your help. I believe we have things in hand for now.

[Rahul Thakur]

In Reply to Parent Post by jmarcus

I'm fairly new to the GR&R process. I've ran two so far with not great results. I've ran a Digital Caliper and a Viscometer. My question is about the viscometer

We don't have many lots of product to choose from, so I figured if I can't have 10 samples and 3 trials I would do 3 samples and 10 trials.

Our product is solvent based, has a tolerance of +/- 30 mPa and it seems to change over the 20 minutes it takes to measure it, not much 2-3 units, but still changes.

I plug it into our GR&R spread sheet and I get numbers in the 40-50%.

I do not understand how the statistical date is working. I would think a 5% change could still be controlled with us knowing that it will change slightly over time.

Plus all the readings were well within Tolerance.

Is there a trick in running GR&R on a product that isn't 100% stable?

Thank you in advance.

The first thing to be checked before undertaking G R&R is whether Viscometer can be considered as a Gauge.Because by a sheer definition of a gauge, it is an instrument with dialed or graduated scale to measure the dimension , capacity etc.Viscosity is neither of these.Secondly G R & R is one of the costiliest MSA technique for an equipment like Viscometer where you have to carry our the measurements in accordance with IP / ASRM standards.And a good GAUGE R&R requires 5*3*3 matrix of 5 parts,3 appraisers & 3 measurements per part per appraisers.

[Jim Wynne]

In Reply to Parent Post by Rahul Thakur

The first thing to be checked before undertaking G R&R is whether Viscometer can be considered as a Gauge.Because by a sheer definition of a gauge, it is an instrument with dialed or graduated scale to measure the dimension , capacity etc.Viscosity is neither of these.

For general manufacturing purposes, a gage is any device that's used to measure something. For viscosity measurement, even a simple Zahn cup qualifies as a gage.

In Reply to Parent Post by Rahul Thakur

Secondly G R & R is one of the costiliest MSA technique for an equipment like Viscometer where you have to carry our the measurements in accordance with IP / ASRM standards.And a good GAUGE R&R requires 5*3*3 matrix of 5 parts,3 appraisers & 3 measurements per part per appraisers.

Further up the thread Miner gave good advice (as usual) with regard to MSA for destructive measurement.

[bobdoering]

If I was to do a GR&R on a viscometer, I would use stable viscosity standards to verify the results. Some materials do continue to change their viscosity as the shear continues. That is not the viscometer's fault. You want to know if the gage and the technique are adequate. If you can get standards about the viscosity range of the usage, and do your random testing, I would think you would get meaningful, repeatable data without going to the destructive testing approach.

[julsbear]

Years ago, I had this same problem. I went with the viscosity standards. If possible choose at least two standards, near the upper and lower portion of the range of what your products cover.