Operating principles of membrane pressesThe pressure in a membrane press is generated by hydraulic cylinders, which can act from above or from below (see construction veneer press). There are different ways to transfer the pressure from the pressure plate to the membrane or the coating medium. An exception is the principle of "only vacuum", it does not necessarily have a hydraulic system. Only overpressureBetween pressure plate and membrane an overpressure is generated, which presses the membrane to the coating material and the coating material to the workpiece. Only vacuumUnderneath the coating material, a vacuum is applied. The room pressure presses the coating material and the membrane to the workpiece. Vacuum and overpressureBoth technical methods are combined, the maximum achievable pressing power is increased. Presses with double membraneTop and bottom of the press are equipped with a membrane. The overpressure can be generated with air or a fluid (liquid system). So, both sides of the workpiece can be coated simultaneously. Especially suitable for veneer processing. Presses without membraneIn vacuum and/or overpressure it is also possible to press without a membrane. The film replaces the function of the membrane. This technical principle cannot be used for veneer, because of its air permeability. It is suitable e.g. for high gloss films, because their sensitive surface should not get in contact with a membrane. Examples
Liquid-systemThe mode of operation is similar to overpressure. Instead of air, the pressure to the membrane is generated with a fluid, e.g. oil. Compared to (air) overpressure, the liquid-system is more demanding (e.g. when changing the membrane), but offers the following advantages:
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