Heidelberg’s Stahlfolder customers now have the opportunity to significantly increase the productivity of their buckle plate folders in the Stahlfolder TH and TD series. This is possible thanks to two new steps introduced by developers at Heidelberg.

The sheet to be folded is simply rotated 90 degrees at the feeder and a new pneumatic twin lay system has been implemented before the second folding unit. As a result of the sheet's shorter feed length at the same press speed, the performance is increased by around 30 per cent depending on sheet format.



Fig. 1: Oblong sheet feed
Productivity can be increased by up to 30 per cent simply by rotating the sheet to be folded at the feeder. 
Before the new pneumatic twin lay system was implemented, the problem of the extra speed generated by oblong feeding impacted on the second unit. Although the reduced feed length had a positive effect on the feeder and first parallel folding unit, the full feed length still had to be transported at the second unit, which was rotated by 90 degrees. This concept demanded very high speeds at the second unit, which sometimes led to problems with reliability and quality of the folding process.

The pneumatic twin lay system now makes it possible on the second folding unit to align and transport folded sheets in parallel using two side lays. This means that twice as many folded sheets can be transported as before, thus enabling customers to halve the speed of the second unit. Oblong sheet feeding into the first parallel folding unit at the same speed increases productivity significantly and, thanks to the low speed of the second unit, also improves the folding quality, which further improves the reliability of the folding process. 



Fig. 2: Oblong feed on folders without a pneumatic system 
In the past, oblong feeding led to problems in speed between the first parallel folding unit with reduced feed length and the second folding unit, which had to transport the full sheet length due to the requisite 90 degree rotation. Pneumatic twin lay systems are ideal for use in folders in the TD and TH series. A buckle plate folder that is one format class bigger than the sheet's format class may be required for the oblong sheet feed process. Pneumatic twin lay systems can be retrofitted on existing folders. This oblong sheet feed makes it possible to change the folding layout, thus providing opportunities for saving paper and time throughout the production process - from prepress to the finished product.



Fig. 3: The system ahead of the second folding unit is the key.
The pneumatic twin lay system makes it possible on the second folding unit to align and transport folded sheets in parallel using two side lays. This halves the speed of the second unit without impacting on the sheet rate. 

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