Processing unit in machines for the chip removing surface processing of panel-shaped workpieces.

A sanding belt is clamped spirally on a metal cylinder. A soft felt-surface can be attached between cylinder wall and sanding belt.

It is used in drum sanding machines, the precursors of the wide belt sanders, as sanding aggregate affecting the workpiece's surface. Drum sanding machines were replaced by wide belt sanders due to their improved quality level. But manufacturers of lightweight-wood processing technology took over the principle again and used it for their products.