The common faults and solutions that may occur during the operation of the extrusion granulation unit are as follows:

1、 Main motor system malfunction

1. The torque of the main motor is too high or too low

   • reasonMalfunctions in the lubricating oil system, poor alignment between the output shaft of the main motor and the inlet/outlet shaft of the gearbox, vibration of the motor and clutch, excessive feed load or poor material melting, etc.
   • solution：
     • Regularly inspect and clean the lubricating oil system, and replace the lubricating oil.
     • Check the alignment between the output shaft of the main motor and the input shaft of the gearbox, and promptly verify the bearings.
     • Conduct electrical testing and inspection to identify the cause of unstable bearing rotor, and adjust the dynamic balance of the clutch.
     • Regularly check the heating and cooling system to ensure uniform feed temperature and good melting state.
     • Control the feeding speed and amount well to ensure stable power of the main motor.

2. The temperature of the main motor bearing is too high

   • reasonPoor bearing lubrication, severe bearing wear, etc.
   • solution：
     • Check and add lubricant to ensure that the bearings are well lubricated.
     • Check the motor bearings and replace them if necessary.

3. The temperature of the main motor winding is too high

   • reasonMotor winding short circuit, motor phase loss operation, etc.
   • solution：
     • Use a multimeter to check the motor winding. If there is a short circuit, repair or replace the motor.
     • Check the three-phase power connection of the motor to ensure normal supply of three-phase electricity and eliminate phase loss faults.

2、 Transmission system malfunction

1. Friction clutch malfunction

   • reasonThe instantaneous starting voltage of the main motor is too low, the friction disc and friction plate are overheated or aged, and the air pressure of the friction disc is too low.
   • solution：
     • When starting the main motor, avoid peak electricity consumption, reduce the feeding load, and restart with a minimum interval of 30 minutes.
     • In summer, when starting the main motor twice or more repeatedly, the interval time should be extended or a fan should be used to force cooling.
     • Use instrument air to blow and wipe off the dust stains on the friction plate and friction disc surface with a cloth. If the wear is severe or there is a "glass like" phenomenon on the surface, the friction plate and friction disc should be replaced.
     • Confirm whether the air pressure value can make the friction disc and friction plate fit together.

2. gearbox failure

   • reasonDeviation of gearbox shift lever position, low outlet pressure of gearbox lubricating oil pump, or high oil temperature.
   • solution：
     • Adjust the gear shift lever position to the correct position.
     • Check the gearbox lubricating oil pump to ensure that the outlet pressure is normal and the oil temperature is within a reasonable range.

3、 Fault in the screw process section of the extrusion granulator

1. Excessive melt pressure

   • reasonHigh mesh size of the filter screen, low melt index and large feeding amount of polypropylene powder, low temperature of each section of the cylinder causing incomplete melting of the material, low opening rate of the template causing obstruction of material extrusion from the machine head, etc.
   • solution：
     • When producing low melt index products, low mesh filters should be used and throttle valve opening should be increased to reduce back pressure.
     • Timely replace the filter screen, monitor the quality of various additives and the ash content in polypropylene powder.
     • Reduce the feeding load.
     • Under the condition of not affecting the quality of extruded products, increase the temperature of each section of the cylinder to raise the temperature of the polypropylene melt and increase the flowability of the material.
     • After the extruder stops, increase the head temperature and maintain it at a constant temperature for a period of time, then thoroughly rinse and clean the template.

2. The screw does not rotate

   • reasonLoose or slipping transmission belt; Gearbox malfunction; Cut off the safety key, etc.
   • solution：
     • Adjust the center distance between the two pulleys and tighten the belt.
     • Check the safety key, analyze the reason for disconnection, and replace the safety key.
     • Inspect and repair the gearbox.

4、 Underwater cutting system malfunction

1. Granulator malfunction

   • reasonExcessive wear of the cutting blade or damage to the cutting edge, excessive vibration of the granulator, and loose fit between the cutting blade and the template.
   • solution：
     • After parking, visually inspect the cutting edge for excessive wear or damage, and if so, replace all cutting blades.
     • Check if the alignment between the cutter shaft and the cutting motor exceeds the tolerance, if the bearing components of the cutter shaft are damaged, and if the dynamic balance of the cutter rotor is unbalanced.
     • Check if there is any gap between the four moving wheels of the cutting cart and the guide rail during operation.

2. Particle water flow rate is too low or too high

   • reasonBlockage of the particle water tank filter and cooler, abnormal inlet and outlet pressure of the particle water pump, etc.
   • solution：
     • Check and confirm if there is any internal leakage of granular water, clean the granular water tank filter and cooler.
     • Check if the inlet and outlet pressure of the granular water pump is normal. If not, inspect the granular water pump and the valves on the pump pipeline.

5、 Other faults

1. Low temperature alarm

   • reasonMalfunction of cooling water solenoid valve, water leakage, instrument malfunction, or excessive throttle opening, etc.
   • solutionNotify the instrument personnel to conduct maintenance and inspect components such as the cooling water solenoid valve and throttle.

2. Interruption alarm

   • reasonThermocouples are disconnected, loose, or malfunctioning.
   • solutionCheck if the thermocouple is disconnected or loose. If it is not disconnected or loose, or if the temperature is too high, notify the instrument personnel for maintenance.

3. Cooling water pump alarm

   • reasonInsufficient water pump pressure, high inlet water temperature of the water pump, overheating of the water pump motor, etc.
   • solution：
     • Check if there is steam in the pipeline and open the front throttle to exhaust the steam.
     • Adjust the water intake to keep the water temperature within a reasonable range.
     • Check if the bearings of the water pump motor or the water pump are faulty, and if necessary, have an electrician or repairman repair them.