Plastic extruder Precautions when powering on the device

After reaching the set temperature, the device can be powered on; before turning it on, the print head and… Plastic extruder Tighten the flange bolts once more to compensate for differential thermal expansion between the bolts and the machine head. When tightening the machine-head bolts, proceed diagonally and apply even torque. When tightening the flange nuts on the machine head, ensure uniform tension around all four sides; otherwise, material misalignment may occur.

Turn on the machine, select and press the “Ready to Start” knob, then engage the “Start” knob. Next, slowly turn the screw speed adjustment knob to initiate a gradual start-up, gradually increasing the speed while adding material in small quantities. During feeding, closely monitor the main motor ammeter and all other indicator gauges for any changes in readings. The screw torque must not exceed the red‑marked limit (typically 65%–75% of the torque gauge’s full scale). Before the plastic profile is extruded, no one should stand directly in front of the die opening to prevent injury caused by bolt breakage or foaming due to moist raw materials. Once the plastic exits the die, promptly cool the extrudate, guide it onto the traction unit and the sizing mold, and activate these devices. Then, based on the readings from the control instruments and the desired properties of the extruded product, make appropriate adjustments to bring the entire extrusion process into normal operating condition, replenishing the feed as needed. The plastic extruder uses a metering feeder to supply material uniformly at a constant rate.

When the die discharge is uniform and the plasticization is good, proceed with traction and sizing. Assessing the degree of plasticization relies on experience; generally, it can be judged by the extrudate’s appearance—its surface should be glossy, free of impurities, foam, scorch marks, and discoloration. When you manually squeeze the extrudate to a certain fineness, there should be no burrs or cracks, and it should exhibit some elasticity. At this point, the material is considered well plasticized. If plasticization is inadequate, adjust the screw speed, barrel temperature, and die head temperature as needed until the desired level is achieved.

During the extrusion process, various process parameters shall be checked regularly in accordance with process requirements to ensure they are within normal limits, and process record forms shall be completed. The quality of extruded profiles shall be inspected according to the quality inspection standards, and any issues identified shall be addressed promptly.

Meanwhile, the plastic extrusion system is maintained through both routine and scheduled maintenance.

Precautions for Plastic Extruders During Shutdown

1. Stop feeding material, extrude all the plastic remaining in the extruder until the screw is exposed, then turn off the barrel and die power supplies and cease heating.

2. Turn off the extruder and auxiliary equipment power supplies to stop the screw and auxiliary machines from running;

3. Open the die head connection flange and remove the die head. Clean the die plate and all components of the die head. To prevent damage to the inner surfaces of the die head during cleaning, use steel rods and steel blades to remove residual material, then sand away any plastic adhering to the interior with sandpaper, followed by polishing. Finally, apply machine oil or silicone oil to prevent rust.

For cleaning the screw and barrel, after removing the die head, restart the extruder and feed in a stop‑material (or recycled material) to flush the screw and barrel. During this process, operate the screw at a low speed to minimize wear. Once the stop‑material has been fully extruded into a fine powder, use compressed air to repeatedly blow out any remaining pellets and fines through the feed port and vent ports until no residual material remains inside the barrel. Then reduce the screw speed to zero, stop the extruder, and shut off the main power supply and the main cooling‑water valve.

Safety considerations during extrusion include electrical hazards, thermal risks, rotating machinery, and the handling of heavy components. The plastic extrusion workshop must be equipped with lifting devices to safely install and remove heavy parts such as the die head and screw, thereby ensuring safe production.