Gap filter, Perforated plate and Expended metal
A large number of PACO filtering and sieving products need supplementary materials and components to ensure that the full potential of PACO metal wire cloths can be consistently fulfilled throughout their long working lives. These primarily include perforated plate, slotted screens and expanded metal. Essential characteristics of these materials, that are particularly valued for their robustness, are precision and finesse – from the choice of materials through to the manufacturing process.
PACOSLOT slotted tubes are available with a range of 27 mm to 37 mm outer diameters and a length of 800 mm to 2400 mm and slot widths from 25 µ upwards. The particular strength of PACO is in the purity of the production technology, which is why they are frequently chosen by food processors and breweries. The specific design of the slotted tube depends on the selected material and required filtering direction (from outside to inside or vice-versa) as well as, in particular, the hydraulic characteristics and associated mechanical requirements.
Slotted screens also provide a smooth transition between sieves and filters. Because of their roots in designs with larger diameter longitudinal and transverse steel rods, they are traditionally used to separate coarser elements from finer substances, such as water or sand. These days, however, slotted screens are finding their way into applications that require slot sizes of less than 0.1 mm and consequently provide extremely fine results. PACO uses slotted screens for screens as well as hollow-bodied slotted sieves which cover a wide range of potential applications – from classifying and dewatering through to filtering and drying.
Perforated plates are punched on large, capital-intensive machines with a punching force of up to 500 t. But it is at the next stage where the real mastery comes into play: as the sheets become severely deformed during punching, they have to be subsequently processed on a straightening line until they are perfectly plane. And after this, unsuspected tension as well as the welding process can cause the sheets to warp. That is why the complete manufacturing and finishing process has to be extremely precisely monitored. Perforated plate is used by PACO as a supporting element in filter cylinders as well as numerous other filter production applications.
Expanded metal is produced by making cuts in a metal surface and then drawing them away from each other – i.e. by expanding the metal. This produces a type of mesh with openings that can have different shapes: diamonds, long strips, hexagons, squares etc. Expanded metal is similar to perforated plate except that no material is lost in the production process. The idea of the inventor was simply brilliant and brilliantly simple. When rolled, expanded metal can be just as flat as perforated sheets. PACO uses these sheets for the stabilization of filter elements, similar to perforated sheets.