Precise, contactless sealing of pouches
To produce the pods, PVOH film is first deep-drawn into a prefabricated mould, and the resulting chambers are then filled with powder, gel or liquid. To ensure a secure sealing of the products, Harro Höfliger uses a modified inkjet printing head which applies water to the covering film in a precise and controlled way: Single-dosed drops of water solubilize the covering film before it is placed onto the filled base film with a roller. This contactless process avoids contamination of the materials, and the fact that the print pattern equals the outer and inner product contours keeps the final product free of water.
In contrast to heat sealing, with water sealing a much narrower and uninterrupted sealing edge can be achieved. After each sealing process a camera system checks whether the water has been applied evenly which is a precondition for a robust sealed seam.
Producing pods in an efficient way
In the case of necessary machine stops, water sealing also proves to be ideal: A special process sequence prevents unsealed products. After the restart of the machine, the film which got stopped directly under the sealing station is moistened with water again, and production continues resulting in a minimum waste of only a few re-sealed products.