What is a vacuum table?

A vacuum table is a work surface on which a workpiece is placed under an airtight sheet or inside a vacuum bag; a pump draws out the air so that atmospheric pressure presses everything down evenly. This lets you glue veneer, laminate and thin layers of wood onto flat, curved or free-form shapes without an expensive counter-mould. In Dutch it is called ‘vacuümtafel’.

How it works

The workpiece sits on or in a mould. A vacuum bag or rubber membrane goes over it. When the pump removes the air underneath, the atmosphere pushes from outside. The theoretical maximum is about 1 bar, roughly 10 tonnes per square metre; in practice you achieve a little less. Because the pressure acts at right angles to the surface everywhere, the material follows concave and convex curves closely.

Vacuum forming

In vacuum forming (thermoforming), a sheet of thermoplastic such as ABS, acrylic (PMMA) or PETG is briefly heated until soft. It is then pulled over or into a mould by sucking out the air between sheet and mould. Once cooled, it keeps its shape. Acrylic baths and shower trays are made this way, usually with a reinforcing layer added underneath.

Application

• Veneering panels, doors and curved furniture parts.
• Bent lamination: pressing thin laminations onto a mould to create a permanent curve.
• Applying HPL or solid surface material to shaped substrates.
• On CNC routers, a vacuum table is also the hold-down bed that clamps sheet material during machining.

Tips and points of attention

• Use a breather layer: a coarse mesh or fabric under the bag lets air escape from everywhere. Without it you get bubbles and loose spots.
• Pick the right glue: for bent work, prefer a glue that cures rigid (such as urea-formaldehyde or epoxy). Ordinary white PVA glue stays slightly elastic, so the curve may spring back after release.
• Limit springback: more, thinner laminations spring back less than a few thick ones.
• Round off sharp edges: sharp corners puncture the bag or telegraph through the veneer.
• Leak test: check without glue first that the vacuum holds.

Related terms

• Veneer
• Counter-mould
• Laminating
• Thermoplastic
• Solid surface

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