A. Gauge Repeatability and Reproducibility (GR&R) is the determination of the accuracy of a measurement by ascertaining its repeatability - the consistency of measurements taken by the same operator - and reproducibility - the consistency of measurements taken by different operators.
There are five major elements of a measurement system that contribute to errors in a measurement process: the standard, the part being measured, the instrument, the operator, and the environment. All of these elements affect the measurement reading obtained. Overall measurement errors are minimized if the errors contributed by each of these elements are minimized.
There are various ways by which the GR&R of a measuring system may be assessed. A common method is to first measure variations due to the measuring equipment. Variations are calculated from measurement data obtained by the same operator taking measurements using the same equipment under the same conditions. Subsequently variations are calculated from different operators taking measurements using the same equipment under the same conditions. Variations may also be calculated from measurement data obtained from several different parts. An overall GR&R value, called the %R&R, is calculated from these combined variations.
The measuring system is considered satisfactory if the %R&R is less than 10%. A %R&R between 10% and 30% may also be acceptable, depending on what it would take to improve the system variability. A %R&R of more than 30%, however, should prompt an investigation into how the R&R of the measuring system could be further improved.
There are five major elements of a measurement system that contribute to errors in a measurement process: the standard, the part being measured, the instrument, the operator, and the environment. All of these elements affect the measurement reading obtained. Overall measurement errors are minimized if the errors contributed by each of these elements are minimized.
There are various ways by which the GR&R of a measuring system may be assessed. A common method is to first measure variations due to the measuring equipment. Variations are calculated from measurement data obtained by the same operator taking measurements using the same equipment under the same conditions. Subsequently variations are calculated from different operators taking measurements using the same equipment under the same conditions. Variations may also be calculated from measurement data obtained from several different parts. An overall GR&R value, called the %R&R, is calculated from these combined variations.
The measuring system is considered satisfactory if the %R&R is less than 10%. A %R&R between 10% and 30% may also be acceptable, depending on what it would take to improve the system variability. A %R&R of more than 30%, however, should prompt an investigation into how the R&R of the measuring system could be further improved.
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