What is the effect of the extruder's porous board and filter?
The filter is the impurities in the melt, and the porous plate is the baffle of the filter, which makes the pressure yield more uniform
The porous plate is also called a shunt plate. It is commonly used in combination with the filter, which is supported by the porous plate and is fitted to the front of the machine. Their function is to put the barrel by screw drive forward rotation movement within the plasticizing molten material, after filter and porous plate into linear movement, prevent the impurity in the molten material through; In addition, due to the barrier of the porous plate and filter, the resistance of the molten material is added, and the quality of the material in the cylinder is improved.
In the back of the filter converter, a gear pump that ensures that molten material is stabilized into the mold can prevent the problem from occurring. However, the temperature changes that occur after the melt material is replaced by the filter will still need to be solved by adjusting the mould. Meanwhile, the gear pump also needs to be protected by a careful filter because the gear pump is easily damaged by hard impurities. Some hard PVC processors do not wish to use the reason of the filter, filter can make PVC plastic melt temperature and prone to degradation, so you need to thermal stability and better materials, thus increasing the cost of materials. The use of PVC for filters can also increase costs. So most of the hard PVC processors either avoid the use of the filter, or use a crude filter without a converter, which filters only the larger particles.
The effect of double screw extruder filter on plastic extrusion is: Double screw extruder filter is very large. When a blocking filter is replaced, the pressure drops suddenly and the temperature of the molten material may fall, causing a change in the size of the product. So technically, in order to maintain the product of the same size, one approach is to adjust the twin screw extruder screw speed, another approach is to adjust the linear velocity of twin screw extruder. When extrusion round products, these changes may not cause serious problems, but in the extrusion flat or irregular shape of the products, plastic melt temperature changes may affect the appearance of product size. For example, in a flat mold, the cooler melt material may make the center of the strip thin, and the surrounding area is thicker. The solution is to adjust the automatic or manual adjustment of the mould.