A Multivariate Sensor for Intelligent Polymer Processing

A multivariate sensor is described for intelligent polymer processing that incorporates a piezoelectric ring to acquire melt pressure as well as a thermopile to acquire melt temperature and mold temperature. The mechatronic system analyzes the process states according to mechanistic relations to estimate the melt velocity and melt viscosity. Validation experiments are implemented to characterize the sensor's performance against an array of commercial sensors. Models of product quality with the described sensor far outperform those based on data from commercial sensors. While system identification of the transient thermopile voltage indicates an underdamped response that limited the model fidelity, the existing capability suggests a new standard for mold design that incorporates multivariate sensors into the runner system to provide a consistent set of physical states for process tuning irrespective of molding machine manufacturer and model.