Taking the guesswork out of thermoforming
Thermoforming is a method of processing plastic sheets by heating them (‘thermo’) to make them pliable and them ‘forming’ them into useful shapes for specific products, including cups, lids, trays as well as dashboards and refrigerator liners. Plug-assists are used to help stretch the plastic materials. Currently, the thermoform process parameters and plug properties for use in developing a specific product are largely determined by trial and error, making the process highly inefficient and simultaneously stifling innovation and competitiveness. The ‘Plug materials influence on final part quality in thermoforming process’ (Plugin) project was designed to develop a user-friendly database of plug/sheet combinations from extensive literature searches, simulation trials and actual thermoforming tests carried out by industrial partners. The goal was to promote faster time to market, optimisation of product properties and reduced material and energy costs for the thermoform industry. Specifically, extensive collaboration among consortium members resulted in a ‘Plug Selector’ expert system of rules regarding selection and operation of plug materials for thermoforming. Virtual trials or simulations exhibited high correlation with industrial test measurements, demonstrating improved predictive capability and significant reduction in the dependence on trial and error methods. The final expert system was implemented using Adobe Authorware 7, due to its user-friendly web-based interface. Currently, it is password accessible only by partners in the Plugin project. However, a bootable, stand-alone CD has also been developed with the goal of widespread dissemination in the future. Continued simulation and industrial trial implementation will expand the database to a much wider range of plug/sheet combinations and process settings. Thus, the Plugin project made significant advances in scientific determination of thermoform process parameters and plug properties. The database should greatly decrease costs and time while increasing future competitiveness of European small and medium thermoform enterprises.
