For plastic extruders, operators must be thoroughly familiar with the machine’s structural features in order to properly control processing parameters and operate the equipment safely. Below, Hebei Shuangda Machinery provides you with the safety operating procedures for plastic extruders.

I. Preparations Before Powering On

1. Materials intended for extrusion must meet the required drying specifications and, if necessary, undergo additional drying.

2. Based on the product’s type and dimensions, select the appropriate die specifications for the plastic extruder, then assemble the machine in the prescribed sequence, installing the die flange, die body, die land, perforated plate, and filter screen.

3. Connect the compressed air line, install the core‑mandrel electric heating rod and the nozzle heating coil, and inspect the water‑cooling system.

4. Adjust the gaps at all locations of the die to ensure uniformity, and verify that the centerlines of the plastic extruder’s main unit and auxiliary equipment are aligned.

5. Start up all operating equipment of the plastic extruder, verify that it is functioning properly, and promptly address any malfunctions detected.

6. Turn on the electric heater to evenly heat and raise the temperature of the die head, the machine body, and the auxiliary equipment. Once the temperature of each component is approximately 10°C above the normal operating temperature, maintain a constant temperature for 30–60 minutes to ensure uniformity between the internal and external temperatures of the machine.

II. Power-On Procedure

Starting up a plastic extruder is a critical step in the production process; improper control can damage the screw and die, while excessively high temperatures may cause the plastic to decompose, and too low temperatures can harm the screw, barrel, and die. The startup procedure is as follows:

1. Start the machine at low speed, run it idling, and check for any abnormalities in the screw and the motor; ensure that the ammeter reading does not indicate overload, and verify that the pressure gauge is functioning normally. Do not allow the machine to idle for an extended period to prevent excessive wear between the screw and the barrel.

2. Feed the material gradually and in small quantities; only begin normal feeding once the material has begun to extrude from the die. Before the plastic is fully extruded, no one shall stand in front of the die to prevent accidents resulting in personal injury or death.

3. Immediately after plastic extrusion, the extrudate must be slowly conveyed to the cooling and shaping section using traction equipment, which should be started in advance. Subsequently, based on the readings of the control instruments and the requirements for the extruded product, appropriate adjustments should be made at each stage until the extrusion process reaches a stable, normal operating condition.

Until the state.

4. Cut and sample. Inspect the appearance to ensure it meets specifications, verify that dimensions comply with standards, perform rapid performance testing, and then adjust the extrusion process according to quality requirements to bring the finished product into compliance with the specified standards.

III. Shutdown Procedure

1. Stop feeding material. Extrude all the plastic from the extruder, then turn off the barrel and die power supplies to prepare for the next operation.

2. While turning off the host power, also turn off the power to each auxiliary device.

3. Open the die head connection flange and clean the porous plate and all components of the die head. Use a copper rod or copper sheet during cleaning, and apply a small amount of machine oil afterward. For cleaning the screw and barrel, if necessary, the screw can be pushed out from the rear of the machine; after cleaning, reinstall it. In most cases, a transition piece may be used.

Material change cleanup.

4. When extruding polyolefin plastics, the extruder is typically shut down under full‑load conditions (with material remaining in the barrel). At this time, care should be taken to prevent air from entering the barrel to avoid oxidation of the material, which could compromise product quality during subsequent production. For PVC plastics, a material‑filled shutdown is also permissible. At that point…

First, close the material door and reduce the temperature at the die head connection (flange) by 10–20°C. Stop the machine once all material has been extruded from the barrel.

5. Shut off the main power supply and the main cooling water valve.

IV. Maintenance and Care of Plastic Extruders

1. The cooling water used in the system is typically softened, with a hardness of less than DH, a non-carbonate hardness of less than 2 DH, and a pH value between 7.5 and 8.

2. When starting up, ensure safe startup procedures are followed; first start the feeding device, and when shutting down, stop the feeding device first. Running the equipment with no material is strictly prohibited.

3. After shutdown, promptly clean the barrel, screw, and the feed ports of both the main and auxiliary machines, and inspect for any agglomerates. It is strictly prohibited to start up at low temperatures or to reverse the machine while material remains in the system.

4. In daily operation, ensure proper lubrication of all lubrication points and the two tandem thrust bearings, and check for leaks at the screw‑seal joints. If any issues are detected, promptly shut down the equipment for maintenance.

5. Regularly inspect the wear of the brushes in the plastic extruder motor and perform timely maintenance or replacement.