Control Charts for Weibull Processes With Standards Given

When the traditional median and range chart limits from s-normal theory are applied to Weibull processes, the risk (the probability of a single point falling outside the control limits) is substantially different from the 0.003 a control chart user might have hoped for. This paper presents new limits for Weibull median and range charts, and proposes two additional control charts. These charts are essentially no more difficult to construct and all have risk 0.003.