An innovative contact heating method in the thermoforming process

For the production of polymer based technical products, consumer goods, and packages forming technologies such as thermoforming processes are used commonly. The heat required for the thermoforming process is usually conveyed by radiation or contact heaters into the polymer sheet. A defined and homogenous Wall-Thickness-Distribution (WTD) is necessary to ensure the functionality and the mechanical stability of the formed container. This paper provides an overview to an approach of WTD optimization. It is realized via a locally defined inhomogeneous heating of the semi-finished good related to the temperature dependent forming behavior of polymers. A new patented method for heating sheets through contact with ceramic thick-film-based resistor heaters will be presented. The WTD is controlled by a fast and locally defined contact heating of the sheet. Therefore, an optimization algorithm for an optimal temperature setup based on a FE-Model had to be developed as well.