1. The positioning of the mouth template is not accurate. Due to the inaccurate positioning of the template in the die head, the gap between the die is uneven, resulting in different degrees of Ballas effect, and the wall thickness of the pipe is uneven after cooling. Countermeasures: correct the positioning pins between the templates and adjust the die gap. 2. The molding length of the die is short. The determination of the molding length of the die is the key to the design of the extruder head. For different pipes, use the forming length to adjust the speed to make the material flow uniform at the outlet. Otherwise, the pipe will appear uneven thickness and wrinkles. Countermeasures: Refer to the relevant manuals and appropriately lengthen the die forming length. 3. Uneven heating of the die. Due to the uneven heating temperature of the die head heating plate or the heating ring, the viscosity of the polymer solution in the die head is inconsistent, and after cooling and shrinking, uneven wall thickness occurs. Countermeasure: Adjust the temperature of the heating plate or heating ring. 4. Die wear is uneven. The die is the part that forms the surface of the pipe, which is in direct contact with the material and will cause wear and corrosion. The uneven wear of the die is caused by the different material flow rate, flow rate, wall pressure and resistance in different parts of the inner wall of the die and the diverter cone. The plastic can get a certain shape and size after passing through the die. Therefore, die wear will directly lead to uneven thickness. Countermeasure: Use the method of "throttling and open source" to repair the gap of the mouth template or the angle of the diverter cone. 5. The material contains impurities that block the flow channel. The blockage of the flow channel makes the flow rate at the outlet of the die uneven, and the material is not stable, resulting in uneven wall thickness of the pipe. Countermeasures: Pay attention to the cleaning of raw materials, and clean up impurities in the flow channel of the die.
