Injection molding machine repair those things

Dec. 23, 2020

Injection Molding Machine is also known as injection machine. It is the main molding equipment that uses plastic molding dies to make thermoplastic or thermoset plastics into various shapes of plastic products. Divided into vertical, horizontal and all-electric. The injection molding machine can heat the plastic and apply high pressure to the molten plastic to make it eject and fill the mold cavity.

After the injection molding machine motor starts, the pressure gauge is under pressure




1): The magnifying board is broken. Use a multimeter to measure whether there is current passing, and repair the amplifier board.


2): The overflow valve is stuck. Remove the overflow valve to check and clean the overflow valve.


After the injection molding machine is turned on for a period of time, the oil pump sounds loudly. Troubleshooting




1): The quality of the suction pipe is not good. Remove the filter to check for deformation. Whether the suction pipe is stratified. Replace the oil pipe and filter.


2): The filter is not clean. Whether the hydraulic oil has too much impurities. Clean the filter.


3): Oil pump wear: check the oil pump oil pan and rotor end surface. Replace the oil pump.


Crawling fault treatment of injection molding machine




1): Poor lubrication conditions. "Pause—Slide—Pause" appears. Increase the amount of lubrication.


2): The system is immersed in air. Need to exhaust.


3): Reasons for mechanical rigidity. The parts are worn and deformed, causing the frictional force to change and creeping. Replace parts.

Analysis of Causes of Hydraulic Oil Pollution in Injection Molding Machines

Injection Molding Machine

Injection Molding Machine


Cause oil pollution:


1): Air mixed with oil. The main banquet is due to poor tightness of pipe joints, hydraulic pumps and hydraulic cylinders. It is manifested by bubbles on the fuel tank.


2): Water is mixed into the oil. Makes the oil milky white. The main reason is that the cooler is leaking.


3): Solid impurities are mixed in the oil. Mainly chips, welding slag, rust and metal powder.


4): Gelatinous substances are produced in the oil. The main feature is that the seal is eroded by the oil or the oil is deteriorated, causing the oil to produce a gelatinous substance, which often blocks the small holes.


Troubleshooting of loud noise when the Vertical Plastic Injection Molding Machine is opened




1): The proportional linearity is poor, and the position of the mold opening and closing time is poorly adjusted. Check the ramp up and down of the amplifying board, adjust the ramp up and down of the amplifying board, and adjust the time appropriately.


2): The lubrication of the hinges of the clamping machine is poor. Check the lubrication of the collar, the second plate and the sliding feet, and increase the lubrication.


3): Mold clamping force is too large, check the clamping force when the mold is stressed, and reduce the clamping force according to the user's product condition.


4): The deviation of the parallelism of the first two boards, check the parallelism of the two boards. Adjust the parallel error of the second board and the head board.


5): Slow to fast mold opening position is too small and speed is too fast. Check whether the position of slow mold opening to fast mold opening is appropriate, and whether the slow mold opening speed is too fast. Lengthen the slow mold opening position and reduce the slow mold opening speed.

Troubleshooting of the out-of-control ejector pin when the injection molding machine is semi-automatic




1): The thimble board is broken, check whether the circuit is normal and the normal voltage is DV24V. Repair the thimble board.


2): The wire is broken, check the switch connection line and I/O board connection line thoroughly. Check the wiring and rewire

Troubleshooting of injection molding machine without thimble action




1): The thimble limit switch is broken, check the DC24V line with a multimeter. Replace the thimble limit switch.


2): Stuck valve, use a hexagonal spoon to press the thimble to check whether the valve core is movable, and clean the pressure valve


3): The thimble limit lever is broken, take out the limit lever by hand after stopping the machine, and replace the limit lever.


4): The thimble switch is short-circuited, check the 0 voltage of the thimble switch to ground with a multimeter, and replace the thimble switch.

Manual termination with mold opening, semi-automatic termination without mold opening




1): The mold opening valve is leaking. After shooting the table manually, observe that the second plate moves back quickly and replace the mold opening valve.


2): Improper adjustment of the ramp up and down of the amplification board, check the amplification slope for a long time, readjust the amplification board ramp time.

The injection molding machine cannot be used for high pressure when clamping the mold, and it exceeds the stroke.




1): The limit switch exceeds the limit, check whether the mold adjustment is appropriate, and adjust the appropriate mold thickness.


2): The hydraulic limit exceeds the stroke, check whether the mold adjustment is appropriate, and adjust the mold forward appropriately.


Troubleshooting of injection molding machine's poor clamping




1): A and B holes are adjusted improperly. When the system flow rate is 20 and the pressure is 99, observe whether the clamping action is crawling and readjust.


2): There is air in the oil circuit, listen to the sound of air in the oil circuit, and exhaust.


3): The ramp-up and ramp-down adjustment of the amplifying board is improper. Observe whether the current value of the ammeter is consistent with the rising and falling speed, and adjust the amplifying board.


When the injection molding machine is locked, only the mold opening action is fault handling




1): Connect the wrong wire, check if there is 24VDC to the valve, check the wire and connect it.


2): The valve is stuck or the wrong spool is installed, check whether the spool is installed incorrectly or blocked, reinstall the spool or clean it.


Troubleshooting of Slow Mold Opening When the Injection Molding Machine is Fully Automatic




1): The oil system plate is leaking, check or replace the express clamping valve, and replace the oil system plate.


2): Mold opening valve leaks, start the oil pump to terminate the mold clamping, press the injection platform or the injection action, whether the second plate moves back, replace the mold opening oil valve.


Crawling treatment of injection molding machine




1): The second-plate guide rail and the coring post are worn out, check the second-plate guide rail and the coring post, replace the copper sleeve of the second plate, the coring post, and add lubricant.


2): Improper adjustment of mold opening and clamping speed and pressure. Set flow rate of 20 and pressure of 99. The second plate of mold clamping should not crawl. Adjust the flow proportional valve hole or pilot valve hole and adjust the linear current value of the proportional valve.


3): There is air in the pipes and cylinders, and exhaust.


Injection molding machine opening and closing machine twisting




1): Check whether the lubricating oil pipe is broken, otherwise there is no lubricating oil to the machine, reconnect the oil pipe.


2): The amount of lubricating oil is small, so increase the amount of lubricating oil. It is recommended that 50 molds be oiled once.


3): The clamping force is large, check whether the mold requires a large clamping force, and reduce the clamping force.


4): Current adjustment is disordered, check whether the current parameters meet the acceptance criteria, and readjust the current value.


5): The parallelism is out of tolerance, use a dial indicator to check whether the parallelism of the first two boards is greater than the acceptance standard; adjust the parallelism.


Countermeasures for injection molding machines without mold clamping




1): Check the travel switch in front of the safety door. And fix it.


2): Check the 24V5A power supply, replace the insurance and power supply box.


3): Check whether the spool is stuck and clean the spool.


4): Check whether the I/O board has output and whether the solenoid valve is energized.


5): Check whether the hydraulic safety switch is pressed.


The above solutions can only play a certain role, not necessarily from the root, and some measures will increase the manufacturing cost, such as increasing the diameter of the tie rod, using good materials, etc., so to some extent depends on the manufacturer's choice. For the use of full hydraulic clamping structure, it is a better choice to solve the broken tie rod. However, due to the slow speed and high energy consumption of the traditional hydraulic type, after weighing the Plastic Injection Moulding Machine Manufacturers, the small and medium-sized machines are still the toggle type. It was not fundamentally solved until the emergence of the two-plate type. .

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