News

Trade news

Company news

FAQ

Common Malfunctions of Plastic Granulators and Their Solutions

Time：

2018-10-10

Common Faults and Troubleshooting Measures for Plastic Granulators: Excessive Main Motor Torque Cause Analysis: Faults in the oil lubrication system, misalignment between the main motor’s output shaft and the gearbox input shaft, or vibrations from the motor and clutch can all damage the main motor bearings, resulting in excessive torque. Additionally, an overly heavy feed load or poor material melting can also lead to elevated motor torque. Remedial Measures: Regularly inspect and clean the lubrication system; use vibration analyzers and infrared thermometers to monitor the main motor bearings and generate trend charts. Periodically check the alignment between the main motor’s output shaft and the gearbox input shaft, especially after initial startup or following a bearing replacement, and continue monitoring for at least three months.

Common Faults and Troubleshooting Measures for Plastic Granulators: Excessive Main Motor Torque — Root Cause Analysis: Malfunctions in the oil‑lubrication system, misalignment between the main motor’s output shaft and the gearbox input/output shaft, or vibrations from the motor and clutch can all damage the main motor bearings, resulting in excessive torque. Additionally, an overly heavy feed load or poor material melting can also lead to elevated main motor torque.

Remedial measures: Conduct regular inspections and cleanings of the lubrication oil system, and use a vibration analyzer and an infrared thermometer to monitor the main motor bearings, generating trend charts.

Regularly inspect the alignment between the main motor’s output shaft and the gearbox’s input shaft; perform this check upon initial startup or after three months of operation following bearing replacement. Conduct electrical tests to identify the cause of rotor imbalance, and carry out vibration‑velocity measurements on the coupling; if readings exceed specified limits, re‑balance the rotor. Periodically examine the barrel heating and cooling systems to ensure uniform heating and thorough melting of the material. If, at startup, both the main motor power curve and the melt pressure curve spike momentarily, this indicates that the feed rate is temporarily too high—reduce the feed rate accordingly. Low main motor torque: A malfunction in the feeding system causing the twin screws to run dry can result in abnormally low motor torque. Remedy: Verify whether the additive‑feeding system or the primary material‑discharge system is faulty, and clear any blockages in the plastic pelletizing machine.

Friction Clutch Malfunction: Cause Analysis:

1. The clutch may disengage due to factors such as excessively low instantaneous starting voltage of the main motor, overheating of the friction disc and friction plates, aging of these components, or insufficient air pressure in the friction disc.

2. The instrument air pressure of the friction clutch is too high;

3. The speed difference in the friction clutch is too large. Remedial measures: When starting the main motor, avoid peak‑load periods and reduce the feed rate; ensure a minimum restart interval of 30 minutes. During summer, if the main motor is restarted more than twice in succession, extend the interval or use a fan to forcibly cool the system. Clean the surfaces of the friction plates and discs by blowing with an instrument‑grade air stream and wiping away any surface dust with a cloth. If wear is severe or the surface exhibits “glassing,” replace the friction discs and plates. Verify that the air pressure is sufficient to ensure proper contact between the friction disc and friction plates.

Screw‑section malfunctions include: excessively high melt pressure upstream and downstream of the throttling valve; excessively high melt pressure at the die head; an excessive pressure differential across the screen changer; and failure of the feed valve to rotate, among others. Corrective measures: if, during startup, both the main motor power curve and the melt pressure curve exhibit a sudden spike, this indicates that the feed rate in the feeding system has temporarily become too high; the feed rate should be reduced.