The common fault of the thermoforming sheet extruder and troubleshooting

Thermoforming products are manufactured on the basis of sheets, which are finished by extruder. The plastic is molded into a uniform melt by an extrusion system, and in this process the pressure built up by the screw continuous extruder head.    

The common faults of extruder and troubleshooting are as follows:

I、 

Main motor bearing temperature rise is too high: 

• cause: (1) bearing lubrication is poor. (2) Bearing wear is serious.
• cause: (1) Check and add lubricant. Check motor bearings and replace them if necessary.
  II、The head pressure is unstable:
• the cause: (1) the main motor speed is not uniform. (2) The feeding motor speed is not uniform, and the feeding amount fluctuates.
• treatment method: (1) Check the main motor control system and bearings. (2) Check the feeding system motor and control system.

III、Lubricating oil pressure lower: 

1、Cause: (1) The pressure setting value of the regulator valve of the lubricating oil system is too low. (2) The oil pump is faulty or the suction pipe is blocked.

2、Treatment method: (1) Check and adjust the lubricating oil system pressure regulating valve. (2) Check the oil pump and suction pipe.

IV、The speed of the automatic screen changer device is slow or ineffective:

• the cause: (1) low air pressure or oil pressure. (2) The cylinder (or hydraulic station) is leaking (or leaking oil).
• treatment method: (1) Check the power system of the net change device. (2) Check the seal of the cylinder or hydraulic cylinder.

V、The safety pin or safety key is cut off:

• the cause: (1) the extrusion system torque is too large (2) the main motor and the input bearing are connected to different hearts
• treatment: (1) Check whether the extrusion system has metal and other things into the stuck screw. At the beginning of the occurrence, check whether the preheating heating time or heating value meets the requirements. (2) Adjust the main motor

VI、Extrusion output suddenly decreased:

1、the cause: (1) the feeding system failure or no material in the hopper. (2) The extrusion system enters the hard stuck screw, so that the material cannot pass.

2、treatment method: (1) Check the feeding system or hopper material level. (2) Check and clean the extrusion system.  

VII、Extruder current(Amp.) instability:

1、production reasons: (1) uneven feeding. (2) Main motor bearing damage or poor lubrication. (3) A certain heater fails and does not heat. (4) The screw adjustment pad is wrong, or the phase is wrong, and the element interferes.

2、treatment method: (1) Check the feeder, troubleshoot. (2) Overhaul the main motor and replace the bearing if necessary. (3) Check whether the heater is working normally, and replace the heater if necessary. (4) Check the adjusting pad and pull out the screw to check whether the screw interferes.

VIII、The main motor can not start: 

• the cause: (1) the driving procedure is wrong. (2) There is a problem with the main motor thread, and whether the fuse is burned. (3) The interlocking device related to the main motor works.
• treatment methods: (1) Check the procedure and restart the car in the correct driving order. (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. Oil pump does not open, motor can not open. (4) The inverter induction is not finished, turn off the main power and wait for 5 minutes before starting. (5) Check whether the emergency button is reset.

IVV、The discharge of the extruder head is not smooth or blocked: 

1、the cause: (1) a certain section of the heater does not work, and the material is not plasticized. (2) The operating temperature setting is low, or the molecular weight distribution of plastics is wide and unstable. (3) There may be foreign bodies that are not easy to melt.

2、Treatment method: (1) Check the heater and replace it if necessary. (2) Verify the set temperature of each section, and negotiate with the technician if necessary to increase the temperature set value. (3) Clean and check the extrusion system and the head.

VV、 The main starting current(Amp.) is too high:

1、cause: (1) insufficient heating time, large torque. (2) A certain heater does not work.

2、treatment methods: (1) The application of hand-turning when driving, if not easy, then extend the heating time or check whether the heater is working normally.
VVI、The main motor makes abnormal sound:

1、the cause: (1) the main motor bearing is damaged. (2) A thyristor in the main motor thyristor rectifier line is damaged.

2、treatment method: (1) Replace the main motor bearing. (2) Check the thyristor rectifier circuit and replace the thyristor element if necessary.