What are the reasons for the unstable dimensions of the profiles during the extrusion process? What are the solutions?

During the production of profiles, unstable dimensions are often related to the instability of extrusion. The main reasons are as follows:
① Uneven material feeding at the die opening causes fluctuations in the feed of the extruder;
② Inconsistent plasticization, due to changes in operating conditions, the flow state, residence time, shear strength, and heating degree of the material during extrusion change, resulting in a change in plasticization quality;
③ The material in the exhaust section is sucked into the vacuum chamber, causing a decrease in vacuum degree and resulting in instability;
④ The cross-section of the profile is not uniform, which has a significant impact on the stability of the material flow in the die. Due to the different heat, resistance, distance traveled by the material, etc. that each part of the profile receives in the die, instability occurs during the extrusion process;
⑤ Inappropriate temperature control of the die head causes uneven flow of the material in the die head, resulting in unstable profile dimensions;
⑥ There is stagnant material in the die head;
⑦ The cooling of the profile cross-section is uneven;
⑧ The pulling speed is unstable.
There are many factors causing unstable dimensions of profiles during extrusion. In production, corresponding solutions should be taken based on different causes. The measures mainly include:
① Maintain uniform material feeding at the die opening, and cool the hopper seat to prevent the heat from the barrel from being conducted to the hopper, thrust bearing box, and reduction box, causing the temperature of the feeding hopper to be too high and the material to adhere, resulting in feed fluctuations;
② Maintain stable screw rotation speed and barrel and screw temperatures;
③ According to the characteristics of the profile structure, reasonably control the die head temperature to maintain stable material flow in the die head;
④ Timely clean the foreign objects in the die head flow channel to maintain the roughness of the flow channel wall and increase the fluidity of the material;
⑤ Timely inspect and clean the air path of the forming die to avoid blockage and affect the adhesion force of the profile;
⑥ Timely inspection.
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