Measurement system analysis of viscosity: a Six-Sigma gage repeatability and reproducibility analysis

Abstract

Different viscometer techniques are used to measure the viscosity; however, the repeatability and reproducibility of these measurement systems have not been investigated. Literature suggests that viscometers exhibit measurement variations that can be categorised into variations due to the process, the gage, and the operators. To explore the sources of variations in viscometers, a Six-Sigma gage repeatability and reproducibility (GR&R) study is conducted. GR&R studies utilise two-way ANOVA to separate measurement variation into different components to find the precision-to-tolerance, signal-to-noise ratios and the true process capability index. A software is built to demonstrate the newly introduced measurement assessment chart that pinpoints the suggested but necessary corrective actions. The results of a real industrial data show that rotational viscometers are more reliable than orifice viscometers, however, with moderate capability due to their modest signal-to-noise ratio. The model, assessment chart and the software can be used to assess other gages.