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Weijin Hot Chamber Die Casting Machine Maintenance
Aug 26, 2016

Weijin Die Casting Machine Maintenance

The metal fritters produced constantly during the work period of die casting machine and the oxide produced by melting furnace in the melting process can be attached to the die casting machine; if the machine operates for a long time without timely cleaning, then the components will be damaged and the service life of the machine will be shortened. Besides, after long time of running, the precision of some components will be reduced and the failure rate will increase, which are caused by the aging and deformation (due to the natural wear and tear of the machine) or other reasons. Therefore, the die casting machine should be ensured to be of  good performance and in normal operating condition all the time; except for the correct installation and use, reasonable maintenance and service should be done persistently and timely.Generally, the maintenance and service can be classified into routine one, regular one and productive one. The regular maintenance also can be classified into the monthly, every three months, semiannually and yearly one. The regular maintenance aims to making sure the die casting machine possesses proper properties, which can keep the stability of top quality and the efficiency of high yield during its long running period. Therefore, it is very important to keep the regular maintenance;furthermore,the manager should fully understand and learn about its maintenance matters and urge the operator to do the maintenance and inspection work at the given time.
1.When the die casting machine is started for the first time or after overhauled,check the nitrogen pressure change in accumulator in 40 hours, replace or clean the
 filter core of oil suction in 200 hours, inject the hydraulic oil into oil tank through the 15um filter after being extracted and qualified in 500 hours. Extract and filter the hydraulic oil (or replace oil) every 2000 hours.
2.When the cooler works for a long period, the tube wall surface will be of scale
 gradually and the heat exchange property will degrade, all of these will result in that the cooling requirement cannot be guaranteed; then the machine has to be stopped and needs cleaning immediately. The cleaning period depends on the water quality.Generally speaking, an internal checking and cleaning should be conducted semiannually. If there is too much incrustation at the inner side of the heat tube,please choose the cleaning reagent to soak to dissolve incrustation, and then wash and clean it with clear water and soft brush; pay attention not to leave any residual detergent in the cooler.
3.Before overhauling the parts of hydraulic system, stop the machine and make
 sure there is no residual pressure in pipeline. Remember to release the hydraulic oil pressure in the accumulator before dismounting. While make sure the nitrogen is completely released before overhauling the accumulator.
4.When overhauling and cleaning the elements and circuits of electricity box and
 junction box, turn off the power and never use the compressed air, brush and other tools and clean them with the dust collection method.
5.As the accumulator is a kind of pressure vessel, regular checking (four to five
 years) shall be done by relevant specialized department.
6.Main points of maintenance of the non-automatic oil feeding lubricating oil
 holes of injection interaction pole (proximity switch), and tie bar devices, etc.

Add lubricating grease for the first time after the machine runs for five thousand times;

Add lubricating grease for the second time after the machine runs for ten thousand times;
l
 Add lubricating grease for the third time after the machine runs for twenty thousand times;
l
 Afterwards, add lubricating grease after the machine runs for every ten thousand times;
l Add the lubricating grease appropriately if there is not enough grease at the
 grease fitting.
5.1.Appearance of Die Casting Machine
The appearance of the die casting machine is the most obvious presentation of
 maintenance. When checking the maintenance of a die casting machine, the first thing to look over is its appearance. Thus, it is most important to maintain its appearance,which includes the following aspects:
(1)Insist on cleaning the alloy scraps, greasy dirt attached to the machine before
 coming off duty or during duty shifts. Emphasis on the cleaning of hinge, tie bar, die casting mould and heat working parts.
(2)Check whether there is any oil leakage at the oil tank, hydraulic pump,hydraulic cylinder, hydraulic motor, hydraulic valve, pipe joint and pressure gage as well
 as oil line joint. Solve it in time if any.
5.2.Hydraulic System
1.During the work period of die casting machine, never use the degenerative,thickened or sedimentary hydraulic oil. When replacing the hydraulic oil, never mix the
 old and new ones and make sure the oil tank cover is well put after replacing the oil.
2.For the new machine, the hydraulic oil should be replaced after operating for
 500 hours; hereafter, replace it every 2000 hours. Clean up the filter element by dismounting and socking it in clean diesel oil, cleaning it with steel brush and blowing it with compressed air when replacing the hydraulic oil.
3.When dismounting any high pressure part, such as hydraulic valve, oil delivery
 pipe and others parts, there may be residual pressure inside. Thus, when loosening the bolt, do it slowly. Loosen the bolt completely after all the residual pressure is released.
4.Check the connection parts of each oil connection, the mounting screw of oil
 valve every half a year. If it becomes loose, fasten it in time to prevent leakage or air entrance in the hydraulic system.
5.The overflow valve, proportional pressure valve, reducing valve and other parts
 at the oil line board should be adjusted by professionals. After adjusting the overflow valve and reducing valve, fasten the nut to prevent the adjusted pressure from changing during the work period.
6.The motor should be cleaned and checked every half a year. Under normal
 condition, the lubricating grease should be replaced for the bearing. If there is no hardening for the lubricating grease for the rolling bearing, its life can be prolonged. If the oil becomes dark, there is water bead or dust gather on the oil level, or the grease become hard, the machine should be replaced in time. The motor should prevent foreign matter from entering the machine and prevent the air flue from being blocked in the operation of motor. Once any abnormal case occurs, stop the machine and solve it in time.
7.Inspection requirements of nitrogen pressure
(1)Within three days of the operation of new machine, check whether there is any
 nitrogen leakage to prevent the nitrogen bottle from being damaged during transportation.
(2)After one week of operation, check the machine for the first time. Within the
 next two months, check it every other week. Afterwards, check it every two months.Fill in some nitrogen when the pressure is not enough.
(3)Methods of checking nitrogen pressure are as follows: turn off the motor; reset
 the scram button; twist off the stop valve to load off, and observe the pressure value of the oil pressure at the same time. When the oil pressure reduces to zero, its nitrogen pressure by this time is the nitrogen pressure of quick injection accumulator.Each nitrogen pressure must conform to the specified value of operation instruction.
8.If the hydraulic valve is out of order since the valve element is blocked by foreign
 matters, take out the valve element and clean it with diesel oil (or sock it in clean hydraulic oil), then blow out the foreign matters with compressed air. Note: generally speaking, the valve element is not allowed to be dismantled unless it is certain that the valve element has been blocked by foreign matters.
9.When dismounting the hydraulic parts relating to accumulator, first open the
 stop valve, begin dismounting after all the high pressure oil in accumulator is released completely. Otherwise danger of high pressure oil injection may be caused.
10.Each oil valve of the machine has been adjusted before delivery. Adjust the
 injection pressure, flux, boost pressure and flux according to the needs of die casting products. Other parts involving system pressure, flow ratio control, safety pressure and other aspects are not allowed to be adjusted casually.
(1)
System flushing: generally speaking, there will be not much water logging and colloid and there will be pitchy-like black oil if the oil of die casting machine is changed according to the established procedure. Flush it with 1/31/2 capacity of the new oil in tank, aiming to flush the used oil, leave no or little used oil.If all the oil is not changed and only some new oil is added, the system needs not be flushed. Whether the new oil is from the same brand of the same supplier and whether the anti-wear hydraulic oil is of the same viscosity. Otherwise the mixing experiment is needed, methods of which are as follows: take half of the new oil and used oil and put them into one vessel respectively; put the 1/3 of new oil and 2/3 of used oil into
another vessel and place it at constant temperature of 7080℃ for 24 hours to
 observe carefully whether there is any muddy or deposit in it. If no, it shows that the oil can be used.
(2)
Refuel new oil: the new oil refueling quantity has something to do with the machine type. The specific refueling quantity should conform to the instructions requirements.
(3)
Pilot run: after refueling new oil, do pilot run with zero load for 1015 min. After the temperature and pressure become normal, it can be reloaded and come into regular work
5.3.Electrical Unit
(1) After starting for the first time or replacing the control circuit of motor, make
 sure the moving direction of motor is right firstly in order to prevent damaging the motor. Specific steps are as follows: inching the starting button of motor, observe the moving direction of motor from its tail blade; the motor should run clockwise.Otherwise it is necessary to cut off the power supply, and exchange the two-phased wire of the three-phased wire at the terminal of main electric box at will. Re-inching the starting button of motor to adjust it until the moving direction is right.
(2) When using the Y/△ to start the motor, other operations cannot be
 implemented until the starting indicator of motor becomes light.
(3) Before the pilot run of new machine, check whether each electric circuit is
 connected well and there is no short circuit, no open circuit, no neglected installation and no looseness firstly. The place of each inductive switch and normal limit switch should be accurate. Start the power supply to check whether its functions are in good conditions.
5.2.3.2.Electric Control Box
(1)As electric control box is the key part of electrical maintenance, its use
 management should be strengthened at ordinary times. After opening the electric box or setting the parameters, the electric box door should be locked in time.Non-professionals are not allowed to open the electric box, press the control button in the electric box or set related parameters on control panel.
(2)Clean the electric box every three months. Keep its inside dry and neat. Never
 deposit guide line, metal work, magnetic substance, inflammable items and other sundries into the electric box so as to make sure there is great air ventilation and favorable heat dissipation condition.
(
3)During the daily repair of the internal electric box, the line should be tidy and the wire size should conform to technical requirements. Redundant lines should be cut off. Never connect wires casually or leave the longer wire bare deposit in the electric box. After the repair, the trunking plate should be covered in time and the electric door should be shut and locked.
(
4) Fasten all the terminals in the electric box every half a year for fear of poor contact or electric discharge phenomena caused by the looseness, such as the input and output terminals of contactor and the input terminals of power, etc.
(
5) During the power outage, turn off the main switch of external power source of the machine, switch of power supply and air switch in electric box, and power switch on control panel to prevent circuit component from being damaged or any accident occurrence.


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