Multivariate SPC for recipe preservation of batch processes

The performances of the Hotel ling's T-2 control chart and the squared prediction error control chart based on the multi-way principal component analysis are evaluated for monitoring within batch process variation for the purpose of recipe preservation. A nonlinear model for simulated batch process data is provided. The model allows for cross correlation of error terms at a given time period and serial correlation of error terms across time periods. The performance characterizations of the two monitoring schemes are provided for a variety of levels of cross correlation and serial correlation. The impact of the time period at which process shifts occur is also investigated for the monitoring schemes. The T-2 control chart is recommended for the cases considered. Copyright (C) 2009 John Wiley & Sons, Ltd.