A new characterization approach for heat sealing of polymer packaging films identifying optimum sealing parameters using Pareto-based trade-off analysis

摘要

This paper presents a new approach for characterizing heat sealing processes in packaging machines, which identifies all appropriate and optimum sealing parameters subject to given quality criteria. The presented approach is distinct from established methods, such as heat seal curves or response surface plots, in three aspects: It provides an easy-to-read chart indicating optimum and appropriate settings of sealing temperature and dwell time, as well as process robustness for each parameter set. The data points of the charts are generated directly from experiments without using any regression model. The design of experiments features a determinate sequence of tests and no iterative loops are necessary. The approach stems from a 'trade-off' model of heat sealing and a specific multi-objective optimization method. This trade-off model states that improving seam quality, reducing sealing temperature, reducing dwell time, and increasing process robustness are conflicting objectives. This hypothesis is deduced from a literature review and verified by experiments. The optimization method claims that all optimum sealing parameters are part of the solution of a multi-objective optimization problem, the Pareto-frontier. This hypothesis is elaborated into a design of experiments using the normal-boundary-intersection method, and is verified using a peelable seam and tear seam scenario.