On establishing CCC charts

Abstract

The Cumulative Conformance Count (CCC) chart has been used for monitoring high yield processes with very low process fraction nonconforming. Current work has yet to provide a systematic treatment for establishing the chart particularly when the parameter is estimated. We extend the results from the recent studies by Tang and Cheong [1], and Yang et al. [2] so that engineers are able to construct the CCC chart under different sampling and estimation conditions. We first outline the statistical properties of the CCC chart. We then give new insights on the behaviours of CCC chart when the parameter is estimated. We propose some procedures for constructing the CCC chart when the process fraction nonconforming is given, when it is estimated sequentially, and when it is estimated with a fixed sample size. The proposed steps are implemented using data from a high yield process which, in some degree, demonstrate the effectiveness of the scheme. © RAMS Consultants.