Which Torque Meter do I choose based on CpK studies ?



hi all,

I am assigned to decide which brand of torque meter to choose from depending on the CP & CPK from the data I had collected. I use one torque driver, which is set to 11kgf.cm with specs +/- 0.5kgf.cm. I did 50 times each with 3 different torque meter. can anyone give me advise as the results that I found seems a bit odd.



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Unfortunately, there is not much you can determine from your study. By torque meter, I presume you mean a torque analyzer. This is a measurement device and is properly studied using MSA techniques, not capability studies. The torque driver is a process (not a standard), which is studied using capability.

The problem is that the torque driver is typically less precise than a torque analyzer, so its variability can overshadow that of the analyzer. In your data torque meters A & B have similar variability (test for equal variances), both of which are significantly less than that of C. A & B might be different, but both are influenced by the variability of the driver.

A 1-way ANOVA shows that the means of all three are different, but which one is correct? The range of +- 0.5 includes all three. Only a reference standard could tell which is correct. Were all three calibrated?

I recommend that you perform Bias, Linearity, Stability and R&R studies on this type of measurement device.

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