(6) The roller surface should have some medium height; the gap between the three rollers should be equal to or slightly larger than the thickness of the plate.
(7) The temperature control of the forming mold should be stable. When the temperature is high, the molten material flows faster in the mold; when the temperature is low, the molten material flows slower in the mold. Unstable melt flow rate will cause large longitudinal thickness error of plate (sheet) products.
(8) Pay attention to control the temperature of the working surface of the three rollers, the temperature of the feeding roller should be slightly higher, and the temperature of the discharging roller should be slightly lower. If the temperature of the roll surface is too high, the slab is not easy to come off the roll, and the surface of the product is easy to produce horizontal lines; if the temperature is too low, the surface of the product is not glossy. According to this phenomenon, the temperature control of the roller surface should be adjusted in time.
(9) The running speed of the three rollers should be slightly higher than the extrusion speed of the slab from the die mouth, and the working speed of the three rollers should be controlled smoothly, and the running speed that is too fast or too slow has a great influence on the thickness error of the slab.
(10) When polyolefin plastics are extruded to form plates (sheets), the screw should use a sudden change structure, and non-crystalline high polymer resins such as abs should be used to extrude plates (sheets) with gradual changes.
(11) Extrusion molding of plastic boards (sheets), except that polyvinyl chloride, polyethylene and polypropylene resins are generally not dehumidified before extrusion, other plastics (such as ABS, polyamide, etc.) Dehumidification and drying are required before extrusion. Otherwise, it should be extruded with a vented extruder.
