Design of the statistical control of low fraction nonconforming processes restricted to small samples
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Data
2007-01-01
Autores
Leiras, Adriana
Epprecht, Eugenio Kahn
Costa, Antonio Fernando Branco [UNESP]
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Resumo
We present the non-conventional design of no charts used for the surveillance of processes characterized by a very low fraction nonconforming, with a costly and/or time-consuming inspection procedure. which makes the inspection of large samples prohibitive. Under these circumstances, the trade-off between the false-alarm rate and the speed with which the chart signals process deteriorations is the basis to design the control chart, once [depending on the sample size) the conventional np chart with three-sigma limits offers little protection against false alarms or is slow in detecting process disturbances. The study was motivated by the real case of a newspapers packaging process. The nominal number of newspapers in the package depends on the newspaper's breadth, and packages with a number of newspapers different from nominal are considered nonconforming.
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Palavras-chave
Control by attributes, Design of control charts, Np charts, Statistical process control
Como citar
Producao, v. 17, n. 1, p. 139-150, 2007.