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Five note the use of die casting mould

Update time:2015-02-03 17:27:22Hit:4071
In the use of casting film which require attention: die casting die using characteristics, alloy melt temperature, mold temperature, the work of die casting die, die lubrication adjustment content.
The use of characteristics, die casting die
In die casting production process, die-casting mold parts forming condition is very poor, they are subjected to mechanical erosion abrasion, chemical and thermal fatigue repeated action.
1) of liquid metal in the high voltage, high speed into the mold cavity, friction and shock heated surface of die cavity, the mold surface to cause erosion and wear.
2) of liquid metal in the casting process is to produce slag, slag chemical action of complex on workpiece surface, compound aluminum and iron like a wedge like, accelerates the formation and development of die casting die crack.
3) the thermal stress is the main cause of the crack surface of parts stamping, in the production process each die casting, forming surface in addition to high-speed, high-pressure flushing by liquid metal, also absorb metal release during solidification heat generation, heat exchange. In addition, due to the relationship between the mold material heat conduction, the forming parts surface layer temperature rise sharply, produced a great temperature difference and internal, resulting in internal stress. When the liquid metal filling the cavity, the cavity surface reaches the first high temperature and expansion, and the inner mold temperature is low, relatively small expansion quantity, so that the surface compressive stress. After opening, the cavity surface in contact with air, compressed air and coating by chilling and tensile stress. The alternating stress increases with the continuation of production, when the fatigue limit exceeded the mold material, to produce plastic deformation and cracks of mould surface.
In order to keep the surface durability requirements type mask, thermal fatigue resistance, wear resistance, non stick mould, easy removal parts. So the forming parts using the current application of better 4Cr5MoSiV1 (H13) materials manufacturing.
Two, the alloy melt temperature
Die in the production process in order to better fill to die all concave hole and deep, ensure the metal flow during each other fusion, in the use of die casting die, should correct selection of metal pouring temperature, temperature of the alloy pouring liquid die casting are as follows:
Temperature / material name liquid die casting C
Zinc alloy 420-500
Aluminum alloy 620-690
700-740 magnesium alloy
Copper zinc alloy 850-960
The temperature of die casting alloy selection principle:
1) the temperature of the metal is poured into the lower die, the longer life expectancy;
2) by low temperature casting, it is possible to reduce the exhaust groove depth increases, decreases the risk of spilled liquid metal;
3) by low temperature casting can reduce the pressure chamber and the top rod is engaged opportunity;
4) by low temperature casting can reduce the casting shrinkage hole and crack.
In a word, in the process conditions permit, die casting alloy temperature, or selection of low-temperature casting good.
Three, the die working temperature
Die casting die working temperature and varied according to the die casting alloy, here are some recommended values for alloy mould, selection:
Mold name working temperature / C
Zinc alloy die 150-180
Aluminum alloy die 180-225
Magnesium alloy die 200-250
Copper zinc alloy die 300
Selection principle of working temperature of die casting mould:
1) lower die temperature, casting internal structure loose, air discharge difficult, difficult to molding;
2) the mold temperature is too high, casting a dense internal structure, but casting easy "welding" attached to the mold cavity, sticking to die
Not easy to discharge the casting, while too high temperature will make the die body itself expansion, influence the dimension accuracy of castings.
3) the choice in the appropriate range should die temperature, generally by testing appropriate, constant temperature control for good.
Four, die lubrication
1, the object of lubrication
Lubrication as die-casting mold and die casting type agent, easy to die stripping; die casting mold and press as the active part of the lubricant, reducing friction, improve the service life of die casting die; in addition, also can be used as a coolant for die-casting mould, and lower mold thermal fatigue due to long work, prolong the service life of the die.
2, the lubricant requirements
For the selection of lubricant should meet the following needs:
A. cannot make die casting adhesion in the cavity;
B. cannot die surface corrosion of steel material;
C. could not produce poisonous gas;
D. cannot produce ash in heating;
E. lubrication should be evenly attached to the cavity and the work surface and not be high-pressure metal away.
The preparation of 3, lubricant
A. total loss oil system of 85%-90%+ graphite 10%-15%;
B. heavy oil 100%;
C. 30%+ 30%+ Vaseline beeswax paraffin 14%+ graphite 26%;
D. 25%+ 20%+ 5%+ graphite glycerol water glass of water 50%;
Matters needing attention in 4, when the use of lubricant
A. lubricant can be used for the cavity and a movable part on the surface;
Less B. lubricant spray volume of each, and to be uniform, after spraying the best form a layer of film on the surface of the type.
Adjust the content of five, die casting die
After the die casting die manufacture completes, should pass the test mode to adjust, the correct choice of casting conditions and process parameters, to achieve the stable production of qualified casting, casting.
Tryout before, mold testing personnel should do the raw materials of alloy for die casting for check in advance, to understand the characteristics and properties of die casting alloy materials; also should understand the structure, die casting machine, die casting conditions, properties of die casting process and method of operation.
The correct selection of die casting forming conditions, is a key test mode adjustment. Often encounter such problems, even if the mould design and manufacturing are correct, but because of the improper selection of die casting forming conditions, the same pressure not qualified castings. On the contrary, in some cases, by adjusting the die casting forming conditions, to overcome the shortcomings of the extruding die, the qualified casting. Therefore, mold testing personnel must be familiar with die-casting forming conditions and the role of
(Author:dong)
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