All manufacturing organizations nowadays have a comprehensive measurement instrument calibration process in place, and pay a lot of attention to ensuring that the calibration work is carried out in accordance with procedures. Failing to calibrate the measuring instruments in accordance with requirements would result in the organization falling foul of auditors of the various standards such as ISO 9001, ISO 13485, and FDA regulations. It is greatly surprising then, that so many people, including many of the aforementioned auditors, have so little understanding of the importance of studying the variability of the measuring process. The lack of emphasis in standards such as ISO 9001 and FDA regulations on the need to study measurement system variability, is also a surprise.
Operating a calibration process without Gauge R&R (Gauge Repeatability & Reproducibility) leaves a critical gap in assessing the health of the measuring process; Measurement system variability is not assessed during the calibration process. Routine calibration is, of course, very important. However, I have seen people responsible for the measurement process, shocked when Gauge R&R studies were completed, to learn that the information provided by their carefully calibrated measuring instruments is of little practical use, because the real variability in the manufacturing process that they are attempting to study is smothered by excessive variability in the measuring process.
There are well established methods under the general heading of Gauge R&R available to facilitate the study of measurement system variability. Also, the analytical work can be undertaken with the Gauge R&R modules available in most statistical software packages. Personnel responsible for the measurement process can be readily trained to use modern computer software to design and analyse Gauge R&R studies, which will enable them to see whether the instruments are fit for purpose, and to indicate the direction of corrective actions, should the need arise.
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