Analysis and solutions of ten common malfunctions of extruder

1.The main extruder current is unstable

Causes:
(1) Uneven feeding.
(2) The main motor bearing is damaged or poorly lubricated.
(3) A certain section of the heater fails and does not heat.
(4) The screw adjustment pad is wrong, or the phase is wrong, and the components interfere.
Solutions:
(1) Check the feeder and troubleshoot.
(2) Overhaul the main motor and replace the bearings if necessary.
(3) Check whether the heaters are working normally, and replace the heaters if necessary.
(4) Check the adjustment pad and pull out the screw to check if there is any interference in the screw.

2.The main motor cannot be started

Causes:
(1) There is an error in the boot procedure.
(2) There is a problem with the main motor thread, and the fuse is burned.
(3) The interlocking device related to the main motor works.
Solutions:
(1) Check the program and restart according to the correct boot sequence.
(2) Check the main motor circuit.
(3) Check whether the lubricating oil pump is started, and check the status of the interlocking device related to the main motor. If the oil pump is not turned on, the motor cannot be turned on.
(4) Check whether the emergency button is reset.
(5) The inverter’s induction current has not been discharged, turn off the main power supply and wait for 5 minutes before starting.

3.The machine head is not smooth or blocked

Causes:
(1) A certain section of the heater does not work, and the material is poorly plasticized.
(2) The operating temperature is set too low, or the molecular weight distribution of the plastic is wide and unstable.
(3) There may be foreign objects that are not easy to melt.
Solutions:
(1) Check the heater and replace if necessary.
(2) Verify the set temperature of each section, negotiate with the technician if necessary, and increase the temperature set value.
(3) Clean up and check the extrusion system and machine head.

4.The starting current of the main motor is too high

Causes:
(1) The heating time is insufficient and the torque is high.
(2) A certain section of heater does not work.
Solutions:
(1) Extend the heating time or check whether the heaters of each section are working normally.

5.The main motor makes an abnormal sound

Causes:
(1) The main motor bearing is damaged.
(2) A certain thyristor in the thyristor rectifier circuit of the main motor is damaged.
Solutions:
(1) Replace the main motor bearing.
(2) Check the thyristor rectifier circuit, and replace the thyristor component if necessary.

6.The main motor bearing temperature rise is too high

Causes:
(1) Poor bearing lubrication.
(2) The bearing is seriously worn.
Solutions:
(1) Check and add lubricant.
(2) Check the motor bearings and replace them if necessary.

7.The head pressure is unstable

Causes:
(1) The rotation speed of the main motor is uneven.
(2) The speed of the feeding motor is uneven and the feeding amount fluctuates.
Solutions:
(1) Check the main motor control system and bearings.
(2) Check the feeding system motor and control system.

8.Low lubricating oil pressure

Causes:
(1) The pressure setting value of the pressure regulating valve of the lubricating oil system is too low.
(2) The oil pump is faulty or the oil suction pipe is blocked.
Solutions:
(1) Check and adjust the pressure regulating valve of the lubricating oil system.
(2) Check the oil pump and oil suction pipe.

9.The automatic screen changer is slow or not working

Causes:
(1) Low air or oil pressure.
(2) Air cylinder (or hydraulic station) leaks.
Solutions:
(1) Check the power system of the screen changer.
(2) Check the sealing condition of the cylinder or hydraulic cylinder.

10.The safety pin or safety key is cut off

Causes:
(1) The torque of the extrusion system is too large.
(2) The main motor and the input bearing are not concentric.
Solutions:
(1) Check whether there is metal and other objects in the extrusion system that jam the screw. At the beginning, check whether the warm-up time or the warm-up value meets the requirements.
(2) Adjust the main motor.

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