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The steplessly adjustable window plate system, developed and patented by GEISS, is the most successful development of the latest generation! This system consists of 4 separate plates that are infinitely movable towards each other, replaces the fixed window plate and has already been installed by GEISS in over 400 machines!


The advantages speak for itself:

  • no further investment for different plate apertures for new moulds,
  • no storage capacity for different plate apertures,
  • reduction of retooling times when changing moulds with different sizes, 
  • a correctly tempered window plate, moreover of the right size, is always available in the machine,
  • the infinitely adjustable window plate set meets any requirement. It can always be tempered ready for the sheet loader and can be removed easily since it does not need any fixtures. 

      The steplessly adjustable window plate system by GEISS  


The window plate system includes 4 separate plates movable against each other like in a diaphragm. Our invention allows the stepless adjustment of both axes independently from one another! Except for our smallest sizes, the strokes are always the same. That machine axis which is directed from left to right (generally the longer axis) allows for example for our T series a reduction by 1000 mm and the short axis over the width of the machine by 500 mm! This means for example that in a thermoforming machine size 1800 x 1100 mm (an unusual size) the window plate system can be reduced to a minimum size of (1800 - 1000 =) 800 x (1100 - 500 =) 600 mm. The window plate aperture is always 40 mm smaller. This clamping edge of 20 mm all around is a feature common to all machines of our line and is independent of machine size and type and of the degree of automation of the plant!

This range of adjustment is generally sufficient. After all, the machine surface is reduced steplessly to 24% of its maximum size! Yet smaller sheets may result in an uneconomical use of such a big machine. There are cases, though, in particular with yet bigger machine surfaces, where this range of adjustment is not sufficient. In this case the window plate set may be replaced by another set that allows for still smaller sizes however the stroke always remains at 1000 x  500 mm!).

The experience gathered over many years with this equipment brings about yet another effect which at first was in the background: since the customer need no longer worry about window plates of existing machines, he can completely disregard any consideration for the past when choosing further plants. He simply chooses that size he considers to be optimal. We recall our possibilities of the parametric design.

The motorised adjustment of this option is standard, any size can be selected from the operator's desk. Further steps of automation are described in our option 45). Option 11) describes in detail the interchangeable plate sets.


Please note


Prior to taking a final decision for the nominal size of the thermoforming machine you should thoroughly investigate the strategic possibilities of the adjustable window plate system.

One set of the steplessly adjustable window plate system has always an adjustment range of 1000 (from left to right) x 500 mm. This originally purely technical and ergonomic feature offers on principle 3 possibilities to proceed. First you should realise that the minimum dimensions of the first window plate set do by no means exhaust the possibilities of adjustment of your machine. Option 11) specifies the minimum size necessary for the steplessly adjustable window plate system as conditioned by the machine size.

You realise that the minimum size of the first set - or the main window plate set - can be chosen much smaller. What can be done now and which possibilities are open to you? 

Your point is that the new plant must cover the whole size range from the minimum as conditioned by the design up to the maximum, without ever again having to think or worry about any window plates. You can then make full use of all of the possibilities of this sophisticated invention. Our Option 11)  specifies also how many window plate sets are required to cover all - and really all - sizes, steplessly. We will then determine for you the gradation of these window plate sets. Please take into consideration that in this case it will again be necessary to exchange steplessly adjustable window plate sets, as in earlier times the fixed window plates. Clever planning can help you drastically reduce the number of changes, but was it not your intention NEVER EVER to have to change window plates?


Our parametric design, as you will know, offers you the possibility to freely choose the nominal size of the machine. Why not give up the idea of some standard size and thoroughly review the sheet sizes processed so far or to be processed in future. Is it possible to handle all jobs with a single steplessly adjustable set (or with very few sets only)? This strategic variant involves some work - and will no doubt also impose some restrictions upon you - yet the result can be a more flexible and cheaper machine! If the outcome is a quite unusual machine size, don't let this bewilder you, because it is exactly the size you need!

Many customers want to order the new machine with some scope, hence somewhat bigger than would be necessary at the moment. Yet quotations have already been submitted or strategic targets point in this direction. Here too we have a useful way to use a somewhat bigger machine without the need to choose a minimum size that is too big. Choose the window plate set to cover the current demand but disregard the maximum machine size and wait what the future really holds.

Please consider that the possibility to use the standard fixed window plates remains unchanged! Even if a size is really "exotic" or if a particular small size simply cannot be handled. The range of settings of the stepless clamp frame is much wider since it has been developed in accordance with another technology (and indeed cannot be used as a window plate).

Every quotation has something positive, but also drawbacks. The more thoroughly you examine it, the more satisfied you will be and the greater the competitive edge will be! The enormous possibilities of the steplessly adjustable window plate system have decisively changed the market of the vacuum forming machines! The share of standard sizes has substantially decreased with regard to special sizes. Don't be afraid of special sizes! Our parametric design ensures that you won't get a prototype even when ordering a "non-standard size"! Parametrics is the automated design on the basis of an expert system. Each size is developed in the same way, be it standard size or special!



The various formats can thus be fitted quickly and easily. Further advantages:

  • temperature control throughout,
  • prepared for the feeding machine,
  • easy to remove since not fixed in any way,
  • the window plate need not be changed when changing the format,
  • manufacture and storing of window plates no longer necessary,
  • the clamping system is kept at operating temperature when changing format, i.e. no more "frame heating".  



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