Twin Sheet

The so-called Twin-Sheet process is an enhanced type of thermoforming, economical and sparing to natural resources, for the production of rigid hollow bodies of nearly any geometry. The real inventor is Georg Geiss (patent specification of June 1963).

Method of operation

2 thermoplastic sheets are heated in one cycle and by thermoforming simultaneously welded into a hollow body. The weld areas or spots are freely selectable within the workpiece. Even thicker materials are welded environmentally friendly, without solvents or fillers.

The Twin-Sheet process allows to use the same range of materials as in standard thermoforming. In addition, the sheets may have different thickness and colours. Coloured marks on the sheets provide for better logistics.

The cycle times depend on material thickness, as well as on other variables such as times for heating, cooling, and feeding.  

The Twin-Sheet equipment for the automatic feeding of 2 sheets on various levels has so far been integrated in more than 50 GEISS thermoforming machines of our T series. This equipment is available in 4 variations:

  • pneumatic (max. 70 kN)
  • motorised (max. 200 kN)
  • motorised boost (max. 320 kN)
  • locked hydraulically (max. 2 MN).

So far company GEISS has successfully produced the following parts by the Twin-sheet process:

  • suitcase shells,
  • Telecom booth roof,
  • model planes,
  • shower trays,
  • tractor roofs,
  • aircraft water tanks,
  • light domes,
  • trays,
  • tables for buses and aircrafts.


For more informationen about Twin-Sheet-Verfahren please look here.

 Twin-Sheet T9

Ernst Hombach GmbH & Co. KG, Uehlfeld
fm Kunststofftechnik GmbH, Bösel 


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