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3.4.1 Forming station top heating
The film is heated and shaped in a single advance as already described. In this device the
heating plate is positioned in the forming die top part. When the device is closed, the film is
pressed against the heating plate by compressed air. When the required pressure has been
reached the film is weak enough and compressed air brings the heated film into the forming
chamber with the appropriately designed bottom plates. When the film reaches the walls of
the forming chamber it cools down and maintains its shape.
The forming bottom die is cooled by water so it will not heat up during the forming process.
After the equalisation of the pressure in and outside the forming chamber by ventilation
valves, the forming station opens and is ready for its next cycle.
3.4.2 Forming station with pre-heating
The bottom film is heated and shaped in two separate stroke lengths.
There is a heating plate at the front end of the forming die top part. The film is pressed
against this plate when the device is closed. The forming die top part heats the film until it is
weak enough to be formed. Then the forming station opens and the film is transported one
stroke length forward. Here one stroke length is approximately half the length of the forming
station. The forming station then closes again and the heated film is now in the second part
of the device. Compressed air with or without vacuum support brings the heated film into the
forming chamber with its designed bottom plates. The film stiffens when it touches the cooled
forming bottom die and maintains its shape. At this forming station the warming up time and
the forming time begin simultaneously, thereby shortening the forming cycle time.
3.4.3 Forming station with plug assist and pre-heating
This process has the same configuration as forming with pre-heat and has also takes place
over two strokes. It is only used to create packages with an extreme depth.
Here the forming process is assist by a (heated)* plug to bring the heated film into the
forming chamber. By using a plug, it results in thicker bottom and corners of the deep
package. Plug assist is usually combined with vacuum or compressed air. The film is cooled
by coming into contact with the cooled bottom part.
* Optional
