Meaning
Measurement consistency when a single operator uses the same equipment to evaluate the same dimension on one part multiple times defines the quality of a metrology process. High gauge repeatability ensures that a moulder can trust a single reading to represent the actual state of a production run. It isolates the equipment error from the operator error or the part variation itself.
Without this stability, a quality department cannot distinguish between a process shift and a faulty measurement tool.
Precision Limitation
Precision instruments like digital calipers or coordinate measuring machines require stable environments to maintain their performance levels. Thermal expansion of the tool or the gauge itself can introduce errors that appear as poor gauge repeatability.
Statistical Significance
An assessment often involves ten parts measured three times each by one technician to calculate the standard deviation of the results. This figure is compared to the total tolerance width of the part specification. If the gauge repeatability takes up more than ten percent of the tolerance, the measurement system is usually deemed inadequate for critical dimensions.
Tooling Calibration
Regular calibration against known standards ensures that the mechanical and electronic components of the measurement system remain within their design limits.
