Establishing Multivariate Specification Regions for Incoming Materials

We present a methodology for establishing meaningful multivariate specification regions on incoming materials or components. The approach uses multivariate PLS regression models to extract information from databases and to relate the properties of incoming materials, and the process variables, to the quality measures on the customer's product. The specification regions are multivariate in nature and are defined in the latent variable space of the PLS model. However, they are easy to implement in practice, and they can provide much insight into what constitutes acceptable material. The approach is illustrated using a simulated process, and is then used to establish multivariate specification regions for polymer resin properties in an industrial film process.