Common causes of failure of injection molding machines and how to deal with them

Fault
Cause
Treatment

I. Motor does not run

1. electrical power supply fuse is blown.

2. poor start button connector.

3. tripped overload relay.

4. Main circuit failure, bad disconnector.

Replace the fuse.

Repair or replace the relevant parts.

II. Buzzing sound and no rotation

Missing phase

Check the power supply.

III. Oil pump makes abnormal

1. Suction side inhaling air.

2. Oil filter is blocked.

3. wear in the pump.

4. Oil level is too low.

1. Repair the joints on the suction side. 2.

2. Clean the filter. 3.

3. Repair the oil pump. 4.

IV. Add enough oil.

No action

1. main pressure valve malfunction.

2. amplifier board failure.

3. motor. Faulty oil pump connection flange.

4. The servo valve solenoid coil is glued down.

1. Repair the main pressure valve and amplifier board.

2. Repair the connector. 3.

3. Install the solenoid coil. 5.

V. No mold closing

1. top retreat not in place.

2. the safety door is not closed.

3. the robot does not give the closing signal.

4. Position scale data failure.

5. The directional valve does not operate.

1. Check if the backstop is terminated.

2. Check the circuit of the safety door. Oil circuit. Mechanical fuse. 3.

3. Check the robot position electricity. 4.

4. Check the position scale.

5. Check whether the valve body has a power supply and whether there is jamming.

VI. Not open the mold

1. malfunction of directional valve.

2. insufficient pressure.

3. mechanical jamming of cranking hand.

4. Position scale malfunction.

1. Check the valve body.

2. Adjust open die pressure service.

3. Repair the crank arm.

4. repair the position ruler. 7.

VII. No ejecting

1. No ejector signal from robot.

2. mold opening is not completed.

3. Solenoid valve failure.

1. Check the robot. 2.

2. Check whether the mold opening is completed.

3. Repair the solenoid valve. 8.

VIII. Pressure does not rise or rises slowly

1. pressure regulating valve is not tight enough.

2. air inside the hydraulic cylinder.

3. Faulty regulator.

1. Remove and inspect.

2. Exhaust the air.

3. Check and repair.

IX. Not ejecting

1. poor solenoid valve operation.

2. poor pressure adjustment valve.

3. foreign objects blocking the nozzle.

4. The nozzle is too cold and the material tube temperature is low.

1. Check the solenoid valve. 2.

2. Check the safety valve. 3.

3. Check the nozzle. 4.

4. Check the temperature of each section.

X. No filling

1. bad solenoid valve.

2. bad back pressure adjustment.

3. bad temperature of the material tube.

4. The melted glue is moving but not feeding.

1. Check the backpressure valve. 2.

2. Check the temperature. 3.

3. Screw broken or not slipping. 11.

XI. Electric heat is not normal

1. electrical disconnector malfunction.

2. bad heating ring.

3. bad thermocouple.

4. electric wire short circuit or grounding.

1. replace the damaged accessories.

2. repair the electric wire.

XII. Oil temperature is too high. Oil leakage

1. using pressure is too high 140KGF/CM2.

2. oil pump wear or oil viscosity is too high.

3. insufficient oil quantity.

4. Cooler blockage.

5. The oil cylinder screw is loose.

1. Check the pump and reduce the viscosity.

2. Add enough hydraulic oil. 3.

3. Clean the cooler. 4.

4. tighten the screws. 13.

XIII. Directional valve. 

Pressure valve noise

1. improper adjustment pressure, spring resonance.

2. the valve core is stuck.

3. aging solenoid coil.

4. No solenoid force.

1. Readjust OK.

2. Clean.

3. Replace parts.

4. poor wiring or insufficient voltage check and repair.