Common Faults of Twin-Screw Extruders

During operation, twin-screw extruders inevitably encounter issues. What are the most common problems? Unstable die pressure, failure to start the main motor, fluctuating main motor current, and low lubricating oil pressure. Below is a detailed overview.

1. Instability in the head pressure

Cause: The main motor speed or the feed motor speed is uneven, resulting in fluctuations in the feed rate.

Remedial measures: Inspect the main motor control system and bearings. Inspect the feed system motor and its control system.

2. The main motor cannot start.

Cause: There is an error in the driving program. The main motor’s thread is malfunctioning, and the fuse may have blown.

Remedial measures: Inspect the control program and restart the equipment in the correct startup sequence. Check the main motor circuit. Verify that the lubrication oil pump has started, and confirm the status of interlocks associated with the main motor. If residual induced voltage remains in the variable frequency drive, disconnect the main power supply, wait for 5 minutes, and then restart. Ensure that the emergency stop button has been reset.

3. The host current is unstable.

Causes: uneven feeding, damage or inadequate lubrication of the main motor bearings, failure of a heating element in a particular section, lack of heating, improper screw adjustment shims, phase misalignment, or component interference.

Troubleshooting steps: Inspect the feeder and eliminate any malfunctions. Overhaul the main motor and replace the bearings if necessary. Verify that all heating elements are functioning properly, and replace the heaters if required. Check the adjustment shims, and retract the screw to inspect for any interference.

4. Lubricating oil pressure is too low.

Cause: The pressure-setting value of the lubrication system’s pressure regulator is too low. Oil pump malfunction or blockage in the oil suction line.

Remedial measures: Inspect and adjust the pressure regulating valve of the lubrication oil system. Check the oil pump and the suction line.

The above is an overview of common malfunctions encountered by manufacturers of twin-screw extruders. Operators are encouraged to refer to this information when performing routine inspections, and to consult the suggested troubleshooting procedures if any of these issues arise. We hope this will prove helpful.

A plastic sealing strip extruder is what we commonly refer to as a plastic extruder. Since many sealing strips in our daily lives are made of PVC, it is also called a plastic sealing strip extruder or an elastomer‑plastic extruder.

The applications of plastic extruders are not limited to the extrusion production of plastic sealing strips; they can also be used for extruding products such as plastic pipes and electrical wires. When manufacturing plastic products, it is essential to first adjust the raw material formulation based on the desired product quality and cost.

We use a mixer to blend the raw materials according to the formulation’s ingredient ratios. Once the ingredients are uniformly combined, they can be fed into a plastic pelletizing machine to produce the desired plastic pellets. A plastic pelletizing machine is a type of extruder, so its production process is similar to that of a plastic extrusion line. After the pellets are produced, they are loaded into the extruder’s hopper. From there, the pellets pass through the feeding system into the barrel, where the screw performs shearing, compression, and compounding, among other processing steps. The material is then extruded through the die at the head of the extruder to form the sealing strip in the required shape. Following water‑cooling, the final product is complete. Since product dimensions vary, the appropriate extruder model must be selected based on the specific application.

Hebei Shuangda Rubber & Plastics Machinery Co., Ltd. is a modern enterprise integrating research and development, manufacturing, and sales of complete sets of extrusion equipment for rubber, silicone, and plastics. The company’s main products include rubber extruders, rubber hose extrusion lines, three‑layer composite sealing strip extrusion lines, silicone sealing strip production lines, plastic sealing strip production lines, plastic profile extrusion lines, plastic pipe extrusion lines, elastomer extruders, and other extrusion equipment, as well as production machinery for engineering seals, automotive seals, wire and cable applications, air‑conditioning hoses, braided hoses, automotive hoses, waterstop strips, and related products.