Pressure foundation

The printing foundation is an essential part of letterpress printing machines . In flat-forming and punching machines, the foundation carries the printing form.

In the simplest case, the pressure foundation consists of a flat plate on which the shape (lead, wood, cliché etc.) is arranged in order to then rub or print it off.

A distinction is made between:

horizontal foundations : the form is with the printing side on top (flat-form machines, extraction presses, lithography presses)

vertical foundations : the mold is clamped on a vertical plate (flat-forming machine Miehle-vertical, etc.)

Inclined foundations : foundations that are partly inclined to the vertical (e.g. OHT automatic punching machines)

Movable foundations : printing form carriers whose position changes during the printing cycle (e.g. Liberty crucibles)

The strength and deflection stiffness of the pressure foundation essentially determine the failure of large-scale printing work. Platen printing machines, in particular, require heavily built foundations made of cast iron or steel . In the case of cylinder rotary machines , one does not speak of the foundation, but of the impression cylinder or forme cylinder . Flatform machines still have fixed foundations (very rare construction) and movable foundations (mostly mounted on a cart).