The varnish is at viscosity 150 Pa.s, which translates to 1500 Poise, much too high in viscosity to use something disposable. A 1.32 ml stainless steel pipette comes with the instrument.
In the interim, I've been doing some evaluations of the machine, firstly using the calibration weights. See the first image for the Bias and Linearity check. The instrument reads lower as the tack increases. This isn't of major concern, but there is significant variability in the readings. The second image is the result of 30 day by day checks of the instrument using the 25 unit calibration weight. This is close to the area where we do our testing.
Third and fourth images are from a very short designed experiment that I ran using different temperatures and sample weights. The effect of changing sample weight is obvious.
I suspect that the operators are using the pipette in such a way that air bubbles are present in the sample, reducing the weight of varnish applied. We could talk to them about taking greater care with filling the pipette, but I suspect it may be better to just stipulate that a certain weight be used, even if the density of the sample may change from batch to batch. It's likely that we'll change the test method in just this way.
After that, it would be my intention to push for a Gage test, including all of the operators of the instrument. That way we can potentially see if anyone needs some more training. Any thoughts?
In the interim, I've been doing some evaluations of the machine, firstly using the calibration weights. See the first image for the Bias and Linearity check. The instrument reads lower as the tack increases. This isn't of major concern, but there is significant variability in the readings. The second image is the result of 30 day by day checks of the instrument using the 25 unit calibration weight. This is close to the area where we do our testing.
Third and fourth images are from a very short designed experiment that I ran using different temperatures and sample weights. The effect of changing sample weight is obvious.
I suspect that the operators are using the pipette in such a way that air bubbles are present in the sample, reducing the weight of varnish applied. We could talk to them about taking greater care with filling the pipette, but I suspect it may be better to just stipulate that a certain weight be used, even if the density of the sample may change from batch to batch. It's likely that we'll change the test method in just this way.
After that, it would be my intention to push for a Gage test, including all of the operators of the instrument. That way we can potentially see if anyone needs some more training. Any thoughts?
Attachments
-
37.6 KB Views: 191
-
48.8 KB Views: 164
-
24.2 KB Views: 159
-
23.6 KB Views: 158