Economic Design of X̄ Control Charts Assuming Weibull In-Control Times

Abstract

A computer program is presented that determines the economically optimal design parameters for X̄ control charts where the amount of time the process remains in control has a Weibull distribution. Results of both uniform and non-uniform inspection schemes are presented. For a uniform inspection scheme, the lengths of the sampling intervals are constant. For a non-uniform inspection scheme, however, the lengths of the sampling intervals are chosen to maintain a constant integrated hazard rate over each sampling interval. A single assignable cause model is assumed. The optimal values of the design parameters, sample size, sampling intervals, and control limit coefficient are determined by minimizing the expected cost per unit time.

• Economic Design
• Variable Sampling Intervals
• Weibull Shock Model
• X̄ Chart

Additional information

Notes on contributors

M. A. Rahim

Dr. Rahim is a Professor of Quantitative Methods. He is a member of ASQC.