Advanced Thermoforming, 2nd Edition

Chapter 12Thermoforming and Milling of Large‐Scale Formed Parts (Sheet Machine)

Written in cooperation with Manfred Geiss, Geiss AG, Sesslach, Germany

Several thermoforming methods can be used for the thermoforming of large‐scale formed parts, such as those shown in Figure 12.1. The thermoforming methods are based on two different machine principles: open or closed chamber. In the United States mainly rotary machines are used, and these function by the open chamber principle. In other countries linear machines are often preferred for production. Both systems do not, or only to some extent, support the semifinished parts during heating. For the manufacture of large formed parts, with reduction of the original material thickness, neither of these two methods is suitable. The heating of large parts is not the only problem for production. Primarily it must be guaranteed that the large parts can be handled automatically. The correct material flow with regard to parts having a heavy weight and a large surface area must be obtained, with a quick format changeover for increasingly smaller series. For the handling of the parts the static charge must be counteracted. Subsequently, the automatic further processing of the formed parts also needs to be considered.

If for the production of large‐scale formed parts, the pre‐heating or the finish heating is done in a separate station next to the thermoforming station, then a temperature loss will occur during transportation to the actual forming ...