When the blocked filter is replaced, the pressure suddenly drops and the temperature of the molten material may also drop, causing a change in the size of the product. In order to maintain the same size of the product, the screw speed of the extruder can be adjusted, and the linear speed of the extruder can also be adjusted. These variations may not cause serious problems when extruding a round product, but changes in the temperature of the molten material may affect the form factor of the product when extruding a flat or irregularly shaped product. For example, in a flat mold, the cooler molten material may cause the center of the sheet to be thinner and the periphery to be thicker. This can be corrected by automatic or manual adjustment of the mold. LED Lens - Optical Reflection Element Plastic COB lighting lens,Compound eye array lens,Plastic COB Reflector Lens Dongguan Lianlong Photoelectric Technology Co., Ltd , https://www.lianlonggd.com
Behind the filter inverter, a gear pump that ensures that the molten material enters the mold stably can prevent the above problems. However, the temperature change that occurs after the molten material is replaced by the filter still needs to be solved by adjusting the mold. At the same time, since the gear pump is easily damaged by hard impurities, the gear pump also needs to be protected by a fine filter.
Some hard PVC processors are reluctant to use filters because the filter will increase the temperature of the PVC molten material and tend to degrade. This requires materials with better thermal stability, which increases the cost of the material. If you use a PVC-specific filter converter, it will also increase the cost. Therefore, most rigid PVC processors either shun the filter or use a coarse filter without a converter to filter only the larger particles.