Once there are signs of malfunction during the operation of the casting machine, the operator should pay high attention and observe calmly to determine the location and possible causes of the malfunction, and determine feasible maintenance methods. Operators must be reminded to follow the "work procedures" established by the company and not to operate in violation of regulations to avoid causing greater accidents. To handle machine malfunctions, both cold chamber die casting machines and hot chamber die casting machines can be operated according to the following steps:
1) By observing, listening, and testing, identify the symptoms and location of the malfunction.
2) Analyze the possible causes of the malfunction.
3) Refer to equipment operation records and fault files.
4) Determine the corresponding processing methods and work steps.
5) Hands on maintenance.
 

1、 The oil pump cannot start
Inspection and analysis: Press the oil pump start button and observe whether the motor relay is engaged.
1. If the relay is not engaged, check
1) Whether the motor thermal relay is activated or damaged.
2) Check if the power circuit is functioning properly using a multimeter.
3) Is the start and stop button contact normal, and is the control circuit open.
4) Check if the relay coil is damaged (using a multimeter).
2. If the relay is engaged after the oil pump is started, check it
1) Is the oil pump damaged or stuck.
2) Is the circuit from the relay to the motor normal.
3) Is the oil pump damaged or assembled too tightly. It should be easy to move the coupling by hand, and the axial movement of the coupling should have a suitable gap of about 3-5mm.

2、 Press the oil pump start button, and the thermal relay trips
Inspection and analysis: Press the oil pump start button, and the thermal relay trips. This is related to factors such as current, load, and symmetry of three-phase resistance values.
1) The motor thermal relay is damaged or the setting current is too low.
2) Low voltage causes an increase in current or an imbalance in three-phase voltage.
3) The resistance of the three-phase winding of the motor is unbalanced.
4) The total pressure or dual pump pressure regulation is too high, causing the machine to overload and trip.
5) The oil pump is damaged or assembled too tightly, causing the motor to overload and trip.

3、 No total pressure
Inspection and analysis: After starting the oil pump, press the pressure button and first observe whether the pressure and flow indicators on the ammeter show any readings to determine if there is current in the solenoid coil of the proportional pressure valve (proportional relief valve) and distinguish whether it is an electrical or hydraulic fault.
1. If there is current output, check
1) Whether the oil pump is reversing (clockwise rotation is considered as forward rotation when facing the direction of the oil pump shaft).
2) Check the overflow valve for improper adjustment or jamming.
3) Check if the shut-off valve is closed.
4) Is the throttle valve of the proportional relief valve missing or loose.
2. If there is no current output, check
1) Is the rectifier board functioning properly, and is the pressure proportional amplification board improperly adjusted or damaged.
2) Observe whether the computer is working properly, press the pressure button with your hand, and check if there is any input at the corresponding point on the computer and if there is any output at the total pressure point. If there is no input, check if the circuit between the pressure button and the computer is normal. If there is input but no output at the total pressure point, it indicates that the computer is faulty or the rear door is not closed.
3) Check if the circuit between the output of the electric proportional board and the oil valve is normal, and if the electric proportional coil is normal.
4) Check if the pressure dial is normal.

4、 No automatic
If all manual actions are normal but there is no automatic action, the safety threshold switch should be checked for normal operation and whether the relevant actions have returned to the origin (according to the requirements of the machine manual). For example, the Lijin horizontal cold chamber die-casting machine should meet the following conditions before automatic operation: the input signal of the safety door should light up; Automatic input signal lights up; The lock mode input signal lights up; The top pin return limit input signal lights up, and the hammer in place lights up.
If the manual operation is abnormal, it should be checked and eliminated first.

5、 Cannot adjust the mold
Inspection and analysis: If the machine cannot achieve mold adjustment movement by selecting the mold adjustment method for operation, the following should be checked:
1) Have the conditions for adjusting the mold motion been met.
2) Is the adjustment pressure set too low.
3) Is the manual operation method correct.
4) If there are no issues with the above content, then check the following:
① Is the hydraulic motor for adjusting the mold stuck or is the motor for adjusting the mold damaged.
② Is the valve core of the mold adjusting hydraulic valve stuck.
③ Is there wear or jamming between the transmission pairs of the mold adjustment mechanism.

6、 No action on the entire machine
Inspection and analysis: After starting the oil pump, there is no movement in both manual and automatic modes of the entire machine. Press the pressure button (pressure and flow parameters have been set) manually to see if there is pressure.
1. If there is no pressure, check
1) Whether the rectifier board is damaged or the fuse is burnt out.
2) Is the input and output of P01 board normal.
3) Check if the proportional relief valve is adjusted properly or if it is damaged or stuck.
4) Is the computer working properly.
5) Is the pressure dial damaged, is the circuit functioning properly, or is the pressure flow rate set too low.
2. If there is pressure, check it
1) Is the fourteen way amplifier board functioning properly.
2) Is the 0V wiring of all oil valve lines normal.

7、 Not locking the mold
Inspection and analysis: Close the safety door, press the mold lock button (if there is a mold installed, choose slow speed to avoid damaging the mold), and observe whether the mold lock indicator light on the electrical box panel is on or whether the main computer has a mold lock signal output.
1. If there is no signal output, check
1) Is there a signal input? If there is no signal input, check the external circuit.
2) Is the top pin back in place? If the top pin does not return, the mold cannot be locked.
3) Confirm if the limit switch (made in Jilin) is damaged when the mold is locked in place.
4) If all locking conditions are met but there is no locking signal output, it is computer damage.
2. If the computer has signal output but still does not lock the module, check
1) Check if the locking pressure is normal (press the locking button to observe the pressure value on the pressure gauge).
2) Is the fourteen way amplifier board functioning properly (with both input and output lights on simultaneously during operation).
3) Whether the slow speed valve is properly adjusted or damaged, and whether the mold release valve is improperly adjusted or damaged.
4) Check if the connection between the electrical box locking output and the oil valve circuit is normal, and if the locking solenoid valve coil is normal.

8、 No low voltage locking mode
Inspection and analysis: Observe whether the low voltage lock mode indicator light on the electrical box panel is on.
1) If the light is not on, check the low-voltage lock mode induction switch to see if it can sense or if it is damaged.
2) If the light is on, check if the low-voltage dip code is adjusted properly or damaged.

9、 No high voltage locking mode
Inspection and analysis: If there is no high voltage when the locking mold moves to the high voltage induction switch, the high voltage induction switch should be checked for damage or induction, and the total pressure setting is too low without high voltage locking.

10、 Constant speed lock mode
Inspection and analysis: Observe if the computer has slow input and output.
1) If the computer does not have constant speed input, check if the external constant speed selection knob is connected to the computer's circuit normally.
2) If a computer has input but no output, it is a computer malfunction.
3) If the computer has input and output, check whether the fourteen channel amplifier board is working properly; Is the circuit from the fourteen way amplification board to the oil valve normal; Is the oil valve coil damaged.
4) The valve core of the constant speed hydraulic valve is stuck by foreign objects or the constant speed flow rate is too low.

11、 No mold opening
Inspection and analysis: Firstly, observe whether the mold opening indicator light on the main electrical box panel is on, and whether the main computer has input and output.
1. No signal output check item
1) Is the induction switch for mold opening in place functioning properly.
2) When manual, the mold opening signal light on the computer should be on. Otherwise, check if the wiring between the mold opening button and the computer is normal. If it is normal, the computer has a fault.
3) When automatic, if the automatic selection knob circuit has poor contact (vibration during material feeding may cause automatic signal disconnection), and cannot complete one action cycle.
2. If the computer is working properly (with input and output), check it
1) Is the fourteen way amplifier board working properly.
2) Is the circuit from the fourteen way amplification board to the oil valve normal, and is the oil valve coil damaged.
3) Is the valve core of the mold stuck by foreign objects.
4) Is the mold opening pressure abnormal (observe the pressure gauge).
5) Is the fixing nut between the piston rod and the crosshead loose.
6) After locking the mold, there may be a sudden power outage, and it is also possible that the mold cannot be opened for a long time. At this time, the total pressure should be set to the maximum, and quick mold opening should be selected. Press and hold the pressure button, and then click the mold opening button to make the mold opening motion.
7) Check if there is any leakage in the lock mold cylinder.
 

12、 No pressure injection action (referred to as no feeding)
Inspection and analysis: If the manual operation of the punch moves normally, but there is no injection action during automatic operation, then check the following items (the hot chamber die-casting machine should remove the hammer head for inspection):
1) Is the manual and automatic selection knob functioning properly.
2) The lock mode termination induction switch and the lock mode confirmation limit switch are not properly matched. The lock mode termination induction switch senses, but the lock mode termination confirmation limit switch is not pressed down, or the limit switch is damaged.
3) The feeding termination induction switch is damaged. (Hot chamber die-casting machines do not have this option)
4) Is there an electrical signal from the injection speed and hammer oil valve, and is the valve core in motion.
5) The injection time is too short or the speed adjustment is too slow.
6) The injection oil cylinder is damaged.
7) The hydraulic system has no pressure.
8) Is it in place before deduction. (Cold chamber die-casting machine does not have this item)

13、 No two speed injection motion
Inspection and analysis: The manual operation of the punch is normal, and there is no second speed injection motion during automatic operation. Firstly, observe whether there is a two speed injection signal input from the computer and whether there is a two speed signal output during automatic operation (the hammer head of the hot chamber die-casting machine should be removed for inspection).
1. No signal input check item
1) Check if the second speed sensing switch is functioning properly.
2) Is the injection time set appropriately.
3) Is the one speed movement normal.
2. Computers have signal input and output inspection items
1) Is there input and output to the oil valve for the fourteen way amplifier board.
2) Is the oil valve coil normal.
3) Is the second speed control valve functioning properly, and is the second speed plug-in valve functioning properly.
4) The first speed travel is too long, and the second speed has no travel.
 

14、 Ineffective injection
Inspection and analysis: First, check if there is a second speed signal and if there is a second speed injection. If there is no second speed, refer to the second speed fault analysis. If there is a second speed, check the following items:
1) Whether the first and second speed regulation meet the requirements, and whether the second speed flow regulation can open the second speed flow valve normally.
2) Is the nitrogen pressure of the fast injection accumulator within the required range.
3) Is the injection pressure set too low.

15、 Shoot off the pressure
Inspection and analysis: If there is a sudden drop in pressure during injection of the punch, check it
1) Whether the injection cylinder, pressure reducing valve, and plug-in valve are leaking internally.
2) Is the shut-off valve tightened.
3) Is there nitrogen present? Insufficient or excessive nitrogen pressure.
4) The accumulator is faulty.

16、 Furnace temperature cannot be controlled
Inspection and analysis: After heating the furnace for a period of time, the temperature gauge pointer does not move. The reasons are as follows:
1) The heating probe circuit is reversed, loose, or damaged.
2) The thermometer is damaged.
 

17、 Alarm
Inspection and analysis: If the machine experiences an alarm during manual or automatic operation, with the electrical box alarm light flashing and the speaker on the electrical box emitting a buzzing sound, it may be caused by the following factors (when the machine has a fault display function, it can be directly processed based on the fault location displayed on the screen):
1) Unlocking mold limit alarm: mold opening termination, mold locking termination, induction switch or mold locking termination, confirm whether there are foreign objects blocking the limit switch at the same time.
2) Abnormal alarm for mold locking protection: During automatic production, the low-voltage mold locking protection time has expired, but the mold locking action has not been completed.
3) The voltage of the computer battery is too low: The CPU program battery voltage of the PLC is too low, and the battery must be replaced as soon as possible to avoid program loss.
4) Elbow lubrication alarm: The elbow lubrication oil pressure cannot reach the set pressure.
5) Top pin limit alarm: Both the top pin exit limit and the top pin return limit are sensed by foreign objects.
6) Core pulling limit alarm: The limit switches before and after the core pulling stroke are both ON; or if core pulling is not selected, the core pulling limit is ON.
7) Motor overload alarm: The motor is overloaded and stops rotating at the same time.
8) Adjustment limit alarm: The limit switches for mold thickness and mold thickness are OFF.

18、 No top needle
Inspection and analysis: If the ejector cylinder cannot achieve the ejector pin action, first observe whether the ejector pin working indicator light on the electrical box panel is on or whether the computer has signal output.
1. If the indicator light is not on or the computer has no signal output, check
1) Is the mold properly opened.
2) If equipped with a core extractor, is the core extractor in place.
3) Is the top pin limit switch damaged.
2. If the computer has signal output, check
1) Check if the top needle pressure is normal (observe the pressure gauge).
2) Is the fourteen way amplifier board normal? (Observe whether the top pin output indicator light on the fourteen way amplifier board is on).
3) Is there an open circuit in the circuit from the fourteen way amplification board to the hydraulic valve, and is the oil valve coil normal.
4) Is the top needle oil valve normal and is there any internal leakage in the top needle cylinder.
5) The top pin of the mold is stuck and cannot be pushed out.
 

19、 Computer malfunction
Inspection and analysis: Observe the indicator lights on the computer PLC and conduct the following analysis:
1) The POW power indicator light is not on, indicating no power supply; The green light indicates normal operation.
2) ALM lights up red, indicating that the CPU is not working properly; If the light is not on, it means it is normal.
3) BAT lights red, computer battery failure; Yellow light on, the computer battery is low; If the light is not on, it means it is normal.
4) RUN green light indicates that the CPU is working properly; The light is not on, indicating that the CPU is not working properly.

20、 Hydraulic system oil temperature too high
Inspection and analysis: After the machine has been working continuously for a period of time, if the hydraulic system oil temperature is too high (normal oil temperature is 15-55 ℃), the following items should be checked:
1) The cooling water intake is insufficient, and it is required that the intake meet the requirements.
2) There is too much scale buildup inside the cooler that has not been cleaned as required.
3) The hydraulic oil storage level in the oil tank is below the minimum oil level line.
4) The hydraulic system has internal leakage phenomenon.
5) The inlet and outlet of the cooler are reversed, resulting in poor cooling effect.

21、 Leakage of oil cylinder
Oil cylinder leakage is one of the causes of various faults in oil cylinders.
The leakage of oil cylinders includes two situations: external leakage and internal leakage. Leakage refers to the external leakage of oil cylinders, cylinder heads, cylinder bottoms, oil ports, exhaust valves, buffer control valves, cylinder heads, and piston rods, which can be directly observed from the outside. Internal leakage refers to the leakage of pressure oil from the high-pressure chamber inside the oil cylinder to the low-pressure chamber, which occurs at the connection between the piston and the cylinder wall, and between the piston inner hole and the piston rod. Internal leakage cannot be directly observed. It is necessary to introduce pressure oil from one side, stop the piston at a certain point or terminal, and observe whether the other oil port leaks oil to determine if there is an internal leakage.
Whether it is external or internal leakage, the main cause of leakage is poor sealing and poor bonding at the connection; Secondly, there is internal leakage caused by the expansion of the cylinder under pressure, and external leakage caused by poor welding of oil cylinders with welded structures.

22、 Gooseneck leakage (hot chamber machine)
1) The taper of the material pot is damaged and needs to be repaired.
2) The taper of the nozzle body is incorrect, and a nozzle body that meets the requirements should be replaced.
3) The installation method of the nozzle body is incorrect. Clean the conical hole and nozzle body of the material pot and reinstall them according to the correct method.

23、 Plug nozzle (hot chamber machine)
Stoppage refers to the solidification of alloy material in the nozzle head or nozzle body, which cannot be continuously sprayed for production, mainly due to insufficient temperature. In case of such problems, it is generally necessary to raise the temperature of the nozzle or directly heat it with gas.

24、 Hammer head
1) Check if the feeding piston rod is aligned with the center of the material pot, install the hammer head and see if it can be rotated by hand. If it can be rotated, it is considered aligned.
2) Check if the furnace temperature is normal and if the temperature displayed on the furnace temperature gauge is within the range of 400-430 ℃. (Hot chamber machine)
3) Due to prolonged failure to clean the slag, the slag accumulates more and more in the furnace or there is too little alloy material in the furnace. Generally, the normal alloy liquid level is about 3cm away from the crucible. (Hot chamber machine)
4) The mold gate sleeve does not fit well with the feeding cylinder. (Cold Chamber Machine)

25、 Not deducted front (hot chamber machine)
First, observe whether the front button indicator light on the electrical box panel is on or whether there is a signal output from the main computer.
1. No signal output check item
Check if there is a pre button signal input.
2. There are signal output inspection items
1) Is the connection between the output point of the computer button and the oil signal line normal.
2) Is the feeding pressure regulation normal (observe the feeding pressure gauge).
3) Is the nozzle oil valve and oil cylinder functioning properly.
Attention: If there is a mold, it should be closed first and then fastened to prevent the mold from being knocked off when fastened.

26、 Without deduction (hot chamber machine)
Analysis: Check if the indicator light on the electrical box panel is on or if there is any signal output from the computer.
1. If there is no signal output
Check if there is any input of the buckle signal, such as checking if the second speed travel switch is pressed during automatic or semi-automatic operation.
2. If there is a signal output check
1) Is the feeding pressure regulation normal (observe the feeding pressure gauge).
2) Is the fourteen position amplifier board functioning properly and is the connection between the output point of the computer and the oil valve line functioning properly.
3) Is the nozzle oil valve and oil cylinder functioning properly.

Reprinted from: Special Casting