Title
The economic performance of the Shewhart t chart.
Abstract
In the production of small batches of customized parts, high flexibility and frequent switching of production from one product variant to another could not allow for the implementation of a control chart to monitor the process. In fact, when a short-run production should be started, the distribution parameters of the quality characteristics to be monitored are frequentlytextitunknown and the production run is too short to get sufficient Phase I samples. To overcome this problem, the statistical properties of Shewhart t charts monitoring a short production run have been recently discussed in literature. In this paper, we investigate their economic performance: the SPC inspection cost optimization is constrained by the manufacturing and the inspection activities configuration. The decision variables of the problem include the chart design parameters and the size of batches of parts to be worked and released to the local inspection area. A numerical analysis aimed at evaluating the economic performance of the Shewhart t chart vs the Shewhart chart with known parameters has been performed. The expected economic loss associated with the implementation of the Shewhart t chart is acceptable with respect to the ideal condition of the control chart with known parameters when the cost optimization is achieved without a statistical constraint limiting the number of expected false alarms. Finally, the effect of an erroneous initial set-up on the correctness of the inspection cost estimation has been investigated. Copyright (c) 2011 John Wiley & Sons, Ltd.
Year
DOI
Venue
2012
10.1002/qre.1222
QUALITY AND RELIABILITY ENGINEERING INTERNATIONAL
Keywords
Field
DocType
quality control,short production run,Shewhart control chart,unknown process parameters,costs
Decision variables,Correctness,EWMA chart,Cost estimate,Control chart,Chart,Engineering,Shewhart individuals control chart,Limiting,Reliability engineering
Journal
Volume
Issue
ISSN
28
2
0748-8017
Citations 
PageRank 
References 
3
0.59
7
Authors
4
Name
Order
Citations
PageRank
Giovanni Celano19212.38
Philippe Castagliola252961.65
Enrico Trovato3251.95
Sergio Fichera410211.40