Statistical quality control in micro-manufacturing through multivariate μ-EWMA chart

Micro-manufacturing processes are characterized by high process variability and an increased significance of measurement uncertainty in relation to tight tolerance specifications. Therefore, an approach that separates the superposition of measurement and manufacturing variation is demanded. A novel design for a quality control chart that makes it possible to monitor, control and extract measurement variation from manufacturing variation is proposed. Thus, a definite cause diagnosis on the approval or rejection of micro-components due to errors either in the measurement or in the manufacturing process is possible. The proposed multivariate μ-EWMA chart which is based on weighting each measurement data with its current measurement variation is discussed and benchmarked with traditional control charts.