Economic design of a two-stage control chart based on both performance and surrogate variables
✍ Scribed by Jooho Lee; Woo-Joo Kwon
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 154 KB
- Volume
- 46
- Category
- Article
- ISSN
- 0894-069X
No coin nor oath required. For personal study only.
✦ Synopsis
The traditional approach to economic design of control charts is based on the assumption that a process is monitored using only a performance variable. If, however, the performance variable is costly to measure and a less expensive surrogate variable is available, the process may be more efficiently controlled by using both performance and surrogate variables. In this article we propose a model for economic design of a two-stage control chart which uses a highly correlated surrogate variable together with a performance variable. The process is assumed to be monitored by the surrogate variable until it signals out-of-control behavior, then by the performance variable until it signals out-of-control behavior or maintains in-control signals for a prespecified amount of time, and the two variables are used in alternating fashion. An algorithm based on the direct search method of Hooke and Jeeves [6] is used to find the optimum values of design parameters. The proposed model is applied to the end-closure welding process for nuclear fuel to compute the amount of reduction in cost compared with the current control procedure.