9 common faults in injection moulding machines and how to deal with them
Before repairing the injection molding machine, the first thing is to understand the working principle of the machine completely, such as the electrical principle, hydraulic principle and mechanical principle. Secondly, we should follow the four steps of looking, smelling, asking and cutting. Keep a clear head, do not be in a hurry, first figure out which aspect of the electrical, hydraulic, mechanical failure, a simple distinction can be made according to the following steps.
The following are common failures and treatment methods for reference
One,Oil pump motor does not start：
1、If the motor does not turn, and there is an abnormal sound, immediately close the emergency stop button, 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, the motor ringing no possible button switch, AC contactor line loose, or thermal relay action
3、Oil pump jam caused by the motor does not rotate (at this time the motor has some sound)
4、motor burnout, in accordance with the original specifications repair and find the causes (such as phase failure, overload, AC relay contacts are not good, motor line joints loose, or three-phase power supply voltage imbalance, unstable)
Second, the motor can turn, but not pressure or large pump does not start pressure：
1、small pump solenoid relief valve or pressure proportional valve solenoid coil does not suck or internal spool is stuck by debris, remove and clean, while checking whether the solenoid coil is burned, whether the wiring is loose, or poor contact
2、Oil pump damage, repair or replace the oil pump
3、The oil level is too low, causing the pump to suck empty
4、Whether the oil filter is blocked
5、Is the motor reversing and changing phase
6、there is air inside the oil pump, first bleed
7、Control the main valve heart of the big pump relief valve is stuck, remove the relief valve to clean
Three, does not fit the mold：
1、the safety door travel switch wiring is loose or damaged, the safety door travel is not pressed down, check SQ1, SQ2, SQ3
2、SQ4 travel switch is closed
3、Clamping solenoid valve stuck or solenoid valve socket loose
4、 the ejector pin backward formation switch is not closed
5、the system pressure is not: according to (2) the content of the repair
Four，No injection or slow speed:
1、Injection pressure is low, the speed is too slow: adjust the injection pressure higher, adjust the injection speed faster
2、Plastic heating temperature bottom: elevated temperature
3、Nozzle blockage, remove the heating cleaning
4、Injection time is too short
5、Injection solenoid valve jammed
6、Injection solenoid valve shall not be charged. Check the electrical cause
Five, not pre-shaped or pre-shaped too slow：
1、The pre-molded termination travel switch is closed, dial the bump of the travel switch.
2、One-way throttle shutdown
3、The material temperature is too low, add high material temperature
4、pre-molded solenoid valve jammed, remove for cleaning
5、The pre-molding pressure is too low, adjust the pre-molding pressure higher
6、the screw into the foreign body jammed screw. Disassemble the screw cleaning, barrel cleaning
7、Bad hydraulic motor, bearing jammed
Six, pre-molding screw rotation, but not into the material：
1、The back pressure is too high
2、Insufficient cooling water out of the filling mouth, the material in the filling mouth "bridge"; adjust the water volume, take out the plastic block of the sticky structure
3、Lack of material, add material
4、Screw break
5、the back pressure is adjusted too high, adjust the back pressure low
Seven, can not adjust the mold or mold adjustment difficulties：
1、System pressure adjustment too bottom
2、 after the template tie rod nuts due to impurities, or lack of lubricating oil grease stuck; cleaning tie rod nuts, repair, installation should pay attention to the axial clearance of the four nuts to be consistent, and then add lubricating oil grease
3、Module adjusting solenoid valve jammed or loose socket: check, repair
4、Damaged hydraulic motor, repair or replace
Eight, the hydraulic oil temperature is too high：
1、Oil pump pressure is too high: according to the plastic molding process to adjust the working pressure down appropriately
2、Insufficient oil in the oil tank: add enough hydraulic oil
3、Oil cooler used for too long, full of scale, poor cooling effect, cleaning the cooler
4、The cooling water flow is not large enough, or the temperature
of the cooling water is not low enough
Nine, semi-automatic operation failure：
The semi-automatic operation of the injection molding machine starts with the opening of the safety door and the closing of the travel switch, which signals the machine to do semi-automatic action, then the mold is closed, and after it touches the SQ4 travel switch, the mold is closed, and at the same time the injection starts, and the injection time relay starts timing. When the injection time is up, it will start the pre-molding, and when it touches the switch for the end of pre-molding, it will start the anti-flow, and when it touches the switch for the end of anti-flow, it will start the cooling time relay.
As can be seen from the above, if the manual normal, most of the general by the travel switch and time relay did not send a signal caused. According to the semi-automatic action in the mechanical cycle of that a stage of failure, according to the electrical, hydraulic schematic diagram to find the corresponding control components, check to solve.
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