A vacuum table is a table that uses suction to hold a workpiece in place during machining. It may also be used to hold fabric, paper, or plastic in place while it is being cut or printed on. The strength of the vacuum needed depends on the type, size, and thickness of the material being worked on. Vacuum tables can be bought prefabricated or made by fitting a vacuum unit onto a regular work table.
Essentially, a vacuum table is a box with a vacuum pump connected to it. The top of the box has hundreds of tiny holes. When turned on, the vacuum pump creates a vacuum inside the box. This pulls air down through the holes to fill the void. The suction created is strong enough to hold the workpiece in place even when cutting or shaping tools are pushing against it.
To get a picture of how a vacuum table works, imagine an an air hockey table. The surface of the table has hundreds of tiny holes through which a pump forces air. The air creates a cushion for the puck, making it float. This allows the puck to move with much less resistance than it could on the table alone.
Suppose that, instead of pushing air out the pump, the table sucked air through the holes; this would create a vacuum. Instead of floating, the puck would be pulled flat against the table. If the vacuum force were strong enough, it would be difficult or impossible to move the puck without first turning off the vacuum.
When choosing a pump for a vacuum table, operators should keep in mind that smaller the workpiece, the stronger the force needed to hold it down. This is because, if a workpiece is small, the vacuum has less area to pull against. If a material is permeable, like sheer fabric, air will simply flow through it, and the vacuum may not be able to grip the material firmly enough to keep it from moving.
Though a vacuum table is much more expensive than a simple table and clamp system, many craftspeople find they are worth the expense. As there are no clamps to attach and detach each time the piece is moved, work goes much faster. There is also nothing to get in the way of the cutting or carving equipment as clamps might. Material held by a vacuum table system always lies flat. There is no risk that a wrinkle or buckle will ruin the cut.