標題: Process Capability Evaluation for Square Bumps with Mean Shift
作者: Pearn, W. L.
Hung, H. N.
Tai, Y. T.
Hou, H. H.
統計學研究所
工業工程與管理學系
Institute of Statistics
Department of Industrial Engineering and Management
關鍵字: square bump;process capability evaluation;non-central chi-square;mean shift;stability control
公開日期: 1-九月-2011
摘要: Process capability indices have been widely used in manufacturing industries to provide numerical measures of process potential and performance. In in-plant applications, some inevitable process mean shift may be undetected when the statistical process control charts are applied, particularly, in the bumping process for square bumps. Bothe in 2002 provided a statistical reason for considering such a shift in the process mean to accommodate the undetected mean shifts for normally distributed processes when evaluating process capability. In this paper, we consider a bumping process for square bumps in which the data can be formulated as a non-central chi-square distribution, a class of non-normal distributions. To evaluate the popular yield-based process capability C(pk) more accurately, we accommodate the magnitudes of undetected mean shifts using the modified capability evaluation formula and tabulate the detection powers under various subgroup sizes and non-central chi-square parameters. Based on the modified process capability evaluation, we can provide a more reliable process capability evaluation of capability index C(pk) for square bumps and make more correct decisions. For illustration purpose, a real application in a bumping factory which is located on the Science-based Industrial Park in Hsinchu, Taiwan, is presented.
URI: http://hdl.handle.net/11536/14796
ISSN: 0090-3973
期刊: JOURNAL OF TESTING AND EVALUATION
Volume: 39
Issue: 5
起始頁: 918
結束頁: 927
顯示於類別:期刊論文