For reliefs of low depth to 3.00mm, there is ge-nerated an emptying of the normal punch, with content of irregular rubber. For reliefs with depth more than 3.00mm, a special em-ptying is generated to support the same thickness of rubber in the whole punch, with uniform content of rubber of 0.7mm. In all the top punches an air exit is mechanized in the corners to allow the deaeration during the final stage of the pressing.
They incorporate between the body of the punch and the coating of rubber a chamber of oil that compensates the heterogeneities in the distribution of the load of the alveoles, to distribute equally the pressure keeping the compactness constant in the whole piece. The quantity of oil inserted in every punch is adapted to the different formats and materials, for what it is not necessary to modify it. Nevertheless, the patent system MOLCER of injection of oil (clear number 9901069), allows to change the quantity and the pressure of the liquid inside the punch. The hydraulic punches made by MOLCER avoid the deformation by wavinesses in the smooth face of the tile after the firing, as it happens with the use of hydraulic conventional punches for floor, wall or porcelain tile, obtaining at the same time a perfect compaction. They exist several types of hydraulic punches:
-Cap system (hydraulic basic) .
-Non-return valve system.
-VUI valve system.