Before repairing the injection molding machine, you must first fully understand the working principles of the machine, such as electrical, hydraulic and mechanical principles. Secondly, the ancients must follow the four steps of seeing, smelling, asking, and cutting. Keep a clear head, don't be irritable, first find out which fault is in electrical, hydraulic, or mechanical. The simple distinction can be done as follows:

The following are common faults and solutions for reference

Oil pump motor does not start

1. The motor can't rotate and it makes an abnormal sound. Turn off the emergency stop button immediately, check whether the fuse is blown or loose, and then check whether the three-phase power supply of the motor is normal

2. Press the motor start button, there is no possibility for the motor to sound like the button switch, the line of the AC contactor is loose, or the thermal relay acts

3. The oil pump is stuck and the motor does not rotate (the motor has some noise at this time)

4. If the motor is burned out, repair it according to the original specifications and find the cause (such as phase failure, overload, bad AC relay contacts, loose contacts of the motor wire, or unbalanced or unstable three-phase power supply voltage)

The motor can turn, but it can’t be pressured or the big pump can’t be pressured

1. The solenoid coil of the small pump solenoid overflow valve or pressure proportional valve does not suck or the internal valve core is stuck by debris. Remove and clean, and check whether the solenoid coil is burned, the wiring is loose, or the contact is poor

2. The oil pump is damaged, repair or replace the oil pump

3. The oil level is too low, causing the pump to suck

4. Is the oil filter blocked?

5. Whether the motor reverses and commutates

6. There is air in the oil pump, vent it first

7. The main valve core of the overflow valve of the control large pump is stuck, remove the overflow valve and clean it

Out of mold

1. The safety door travel switch wiring is loose or damaged, and the safety door travel is not depressed, check SQ1, SQ2, SQ3

2. SQ4 travel switch is closed

3. The clamping solenoid valve is stuck or the solenoid valve socket is loose

4. The formation switch of the thimble backing is not closed

5. No system pressure: Press (2) to repair

No injection or slow speed

1. The injection pressure is low and the speed is too slow: increase the injection pressure and increase the injection speed

2. The bottom of plastic heating temperature: increase the temperature

3. The nozzle is blocked, remove and heat for cleaning

4. The injection time is too short

5. The injection solenoid valve is stuck

6. The injection solenoid valve must not be powered. Check electrical reasons

Not plasticized or plasticized too slowly

1. The pre-plastic termination travel switch is closed, and the striker of the travel switch is opened.

2. The one-way throttle valve is closed

3. If the material temperature is over the bottom, increase the material temperature

4. The pre-plastic solenoid valve is stuck, remove and clean

5. The pre-plastic pressure is too low, increase the pre-plastic pressure

6. Foreign matter enters the screw and jams the screw. Disassemble the screw and clean the barrel

7. The hydraulic motor is broken and the bearing is stuck

The screw rotates during pre-molding, but does not feed

1. The back pressure is too high

2. The cooling water from the feeding port is insufficient, and the material in the feeding port "bridging"; adjust the water volume and take out the plastic block with sticky structure

3. Lack of material, add material

4. Screw broken

5. The back pressure is adjusted too high, lower the back pressure

Unable to adjust or difficult to adjust

1. The system pressure is too low

2. The tie rod nut of the rear template is stuck due to impurities or lack of lubricating oil; clean the tie rod nut, repair it, and pay attention to the same axial gap of the four nuts when installing, and then add lubricating grease

3. The mold adjusting solenoid valve is stuck or the socket is loose: check and repair

4. The mold adjusting hydraulic motor is damaged, repair or replace

Hydraulic oil temperature is too high

1. The oil pump pressure is too high: reduce the working pressure appropriately according to the plastic molding process

2. Insufficient oil in the oil tank: add enough hydraulic oil

3. The oil cooler has been used for a long time, it is full of scale, and the cooling effect is poor. Clean the cooler

4. The cooling water flow is not large enough, or the temperature of the cooling water is not low enough

Semi-automatic operation failure

The semi-automatic operation of this machine is that the safety door is opened, the stroke switch is closed, and the machine is sent a signal to start the semi-automatic action, and then the mold is closed. After the SQ4 stroke switch is touched, the mold closing ends, and the injection starts at the same time. The injection time relay starts timing, and the injection time is up. After that, the pre-molding starts, and when it touches the limit switch that has finished pre-molding, it starts to prevent flow. When it touches the anti-flow limit switch, the cooling time relay starts timing. After the time is up, the mold opens, and then the mold opens. After the mold terminates the travel switch, perform the ejection action. After the ejection termination travel switch is touched, the ejection action is performed. After the ejection termination stroke is encountered, the safety door is waited to open, so that the work is repeated. It can be seen from the above that if the manual operation is normal, it is usually caused by the trip switch and time relay not sending a signal. According to which stage of the semi-automatic action fails in the mechanical cycle, compare the electrical appliances and hydraulic schematic diagrams to find out the corresponding control components, and check to solve them.