The raw materials of Dalian extrusion moulding enter the barrel from the hopper, and under the action of screw rotation, they are conveyed forward to the feeding section through friction and shearing between the inner wall of the barrel and the surface of the screw, where loose solids are conveyed forward and compacted at the same time; in the compression section, the depth of the screw groove becomes shallower and further compacted, while heating outside the barrel and friction and shearing between the screw and the inner wall of the barrel
The melt begins to melt when the material temperature rises, and the compression section ends. The homogenization section makes the material uniform, and extrudes the melt at constant temperature, quantity and pressure, then forms behind the machine head, and gets the product by stereotyping. On the premise of guaranteeing the plasticizing quality, the extrusion temperature should be lowered as far as possible. When the extrudate surface is uniform in color, the extrudate surface also carries light from the die.
It can be confirmed that the plasticizing effect is good. If the extrudate surface is very bright, the extrusion temperature can be reduced appropriately. The temperature of the screw middle zone is high, the feeding section is slightly low and the die head is slightly low. It is especially reminded that die temperature setting is also related to die length (distance from screw top to die outlet).
If the distance is long, the temperature of the die is set a little lower than that of the middle, such as 10-20 C. If the distance is short, even if the same grade of raw material is found to be not dry well, the die must be cleaned after re-drying and extrusion. After changing the material, if the extrudate is not smooth, unstable and easy to break, the die head should be removed and cleaned up.