The design and manufacture of punches are now automated and standardized processes, albeit with significant differences depending on the purpose and type of cardboard to be punched (stretched or corrugated) and depending on the type of die-cutter used.
In this article we will find out how to make a die and which are the different steps that make it up.
The process of making a die:
1) The first step foresees that paper converting supplies to the fustellificio a graphic draft of the type of box that will have to be produced with the punch in question;
2) The die-cutter designs the box prototype with a CAD program and makes a sample of it with a plotter. The paper industry controls and tests the prototype and decides its validity;
3) When the prototype is final, we proceed to CAD design of the punch and, in particular, we design:
– the laser cutting of the punch
– the threads and the creasing machine to be processed with automatic bending machines
– gumming of the punch to be processed with water jet or plotter
– the counters or counterplates and extractors to be processed with milling machines
This type of design is carried out by creating files with the extension .CF2 which, through layers of different colors, allow to process in output all the processes designed by attributing a different color to each individual operation to be processed.
After laser cutting of the punch, the threads – relating to the perimeter cut of the box – and the creasers – that determine the bending areas of the box are inserted by hand.
Finally with the phase of gommaggio the die will be complete; this process serves to protect the inserted blades and to facilitate the expulsion during the punching, so as to avoid problems such as paper jams, creation of “angel hair”, pressure recalibration, needle setting etc.
Another fundamental aspect in the die-cutting process of a cardboard box is the choice of which die-cutting machine to use and how many stations it is provided with. In fact it is possible to pass the blank through two other operations:
1) cleaning with an extraction system that knows many technologies such as traditional extraction, dynamic extraction and that linked to new technologies on the market with StripClip®, QuickStrip® etc.
2) layer separation that allows faster stacking of the final product.
The punching in the strict sense takes place with the loading of the punch in the machine, with the preventive “shoplifting”, that is a pressure test of the rollers of the die-cutter on a sheet for the shoplifting. This compensating pressure with special tapes taps is used to thicken and balance the pressure on the whole die. The punch acts as a male in the punching, especially in the areas to be creased, and the female is obtained by means of “counter-rams” which are applied on a steel plate duly cut to the extent of the die-cutting area of the machine. These ropes with the die cords will determine the fold lines of the boxes (creasers).
Here then explained how to produce a die and what are all the steps necessary for this operation.