1.Principle of "Temperature First, Speed Second":
Prior to any adjustment, it is imperative to ensure that all temperature zones (especially the barrel and die) have been fully heated up and stabilized. Adjusting the screw speed before the temperature stabilizes can easily lead to uneven plasticization, machine blockage or screw damage.
2.Principle of "Fine-Tune in Small Steps and Observe Feedback":It is recommended to increase or decrease the speed by 3-5 RPM for each adjustment and observe for at least 10-15 minutes. Make the next adjustment only after the melt pressure, operating current and pipe parison appearance have stabilized. Avoid drastic and sudden speed adjustments at all costs.
3.Principle of "Coordinated Matching and Close Monitoring of Traction":The screw speed and traction speed must be adjusted in a linked manner to maintain a constant traction ratio (usually slightly greater than 1), which is the lifeline for ensuring the wall thickness and dimensional accuracy of pipes. After adjusting the screw speed, the traction speed shall be fine-tuned proportionally immediately.
4.Principle of "Pressure as the Criterion and Risk Prevention as the Priority":For used equipment, melt pressure is the most important indicator for safety and operational status. The normal production pressure shall be within the range of 30-70% of the equipment's maximum allowable pressure. When adjusting the screw speed, if the pressure approaches the upper limit or fluctuates drastically, speed-up shall be stopped immediately and the causes shall be investigated (common causes: screen blockage, local overheating, increased backflow caused by screw wear).
In summary, the essence of adjustment is to strike a balance among output, quality and equipment safety. For used extruders, it is recommended to start at a relatively low speed (e.g., 50% of the rated speed) and optimize gradually on the premise of producing qualified products. The commissioning process must be repeated every time the raw materials or dies are replaced.