Statistical process control for short run manufacturing systems

A Shewhart (X) over bar control chart is developed to monitor the process m ean for large production runs. It has not been considered appropriate to mo nitor the process mean using the Shewhart (X) over bar control chart for sm all production runs. In this paper we propose the design of (X) over bar co ntrol chart to monitor the process mean for small production runs. For vari ous combinations of the number of samples and the size of each sample, cont rol coefficients of (X) over bar control chart are computed by numerical me thods. Using these results, the (X) over bar control chart for small produc tion runs is developed to monitor the process mean correctly. Finally, the design procedure of the (X) over bar control chart for small production run s and the results of misusing the Shewhart (X) over bar control chart are i llustrated by an example.