Advanced Thermoforming, 2nd Edition

Chapter 43Preprinted Film for Lid Thermoforming

For thermoforming of preprinted film, some knowledge about thermoforming methods is required of all parties involved in the process. The printing demands of manufacturers as well as customers are ever‐increasing. Today an offset of print is no longer acceptable on the thermoformed part. So the thermoforming machine technology has had to become more and more precise. As is true for other kinds of thermoforming applications, it is necessary to take the whole production process into consideration in order to successfully produce thermoformed parts. It is clearly imperative that all participating parties work very closely together, that is, the extruder, printer, and thermoformer. Often it is better that extrusion and thermoforming be carried out in the same company, because then it is possible to immediately address the requirements of extrusion based on knowledge gained during the thermoforming. Even better, the film could also be printed at the same company. However, all three processes are only rarely carried out in the same company.

The film has to have a distortion print on it in order to show the correct image after thermoforming. The film index is controlled by print mark registration and a print mark sensor. A good technique is to integrate the print mark sensor in the thermoforming station, between the forming tool and the transport profile of the film transport. Unfortunately, it is then necessary to extrude the material ...