To ensure safe processing, work pieces are automatically clamped to the processing table by means of suction heads. A stable and constant minimum vacuum must be generated to ensure that work pieces are held securely in place during mechanical processing.
Before or after processing, wood must be protected against the destructive effects of environmental influences such as heat, moisture, insects and micro-organisms. The practice of soaking the wood in a preservative solution is widespread, but has the disadvantage that the liquid penetrates only a few millimetres into the wood. Complete protection is possible, however, if the wood is degassed and dried with the aid of a vacuum pump. The preservative agent then penetrates much deeper and optimizes the protective effect.
The use of vacuum dryers in conventional wood drying chambers can reduce a typical drying time from several weeks to a mere 3 to 4 days. During the drying process, pressure in the chamber is gradually reduced to the minimum. The chamber is pressurized with steam and the air is extracted to prevent cracks and colour changes in the wood that can be caused by too high an oxygen content. Radial fans circulate the steam and convey the heat to the wood. Further steam condensate will be exhausted from the drying chamber.