Pressing with vacuum is different from pressing with clamps, veneer presses or other machines. The digital master manual provides you with all the information you need for every vacuum press from Columbus. Here we have summarized the most important things for you:

Press pressure from ALL sides

With conventional presses, the pressing pressure occurs from two sides. However, when vacuum pressing you have to think differently, here the pressing pressure is even ALL SIDES. For this reason, stencils must be closed on all sides, including the BOTTOM SIDE.
A pressing pressure of just under kg/cm² sounds like little at first, but if it acts on a workpiece from all sides, the resulting forces should not be underestimated and can, for example, cause a less stable stencil to implode.
For larger radii (and thicker layers), the distance between the clamps (ribs) of the template can be 60 to 80 mm. For smaller radii and thinner layers, this distance must be reduced accordingly, otherwise waves can form in the workpiece.
To increase stability, transverse reinforcement of the template is required for taller workpieces.

Size of the workpieces/stencil

The distance from the workpiece to the membrane frame or to the next workpiece should be approximately ½ the height of the workpiece. Example: a workpiece with a height of 20 cm should have a distance of 10 cm from the membrane frame on all 4 sides.
During the pressing process, workpieces that are too high or too large can damage the membrane or cause incorrect air to be drawn in (no vacuum is created). The membrane frame should be able to close without applying much force.

Possible forms

Which shapes can be pressed depends primarily on the material and the thickness of the layers used. Bendable plywood and slotted panels (see below) are particularly suitable for form gluing. Otherwise: the smaller the radius, the smaller the layer thickness.

Vertically sloping workpieces

In order to protect the membrane from over-stretching or tearing, very tall workpieces should not fall vertically where no pressing pressure is required. An allowance (e.g. made of Styrofoam) should be included here (see picture).
If the pressing pressure is required on a steep or vertical side, it must be ensured that the membrane can expand below the mold by at least 70 mm. This ensures a high side pressure.

Fixing the layers

To prevent the layers from slipping, they should be secured with adhesive tape.

Protection of the membrane

Sharp corners and edges must be avoided in order not to damage workpieces and membranes. If this is not possible, the membrane must be protected from mechanical damage with felt or fleece.
Attention: an open template, sharp HPL edges or unrecessed fastening material can destroy a membrane within seconds.

In summary: vacuum presses offer an incredibly wide variety of possibilities - but never underestimate the power of the vacuum when implementing your ideas :-)