How to avoid the problem of cracking of die casting mold

Aluminum alloy die steel die-casting mold will produce cracks after a period of production. After analysis, the main reasons for this phenomenon are as follows:

    (1) The mold temperature is too high and the stress is too large

    (2) mold mold material used 8407, skd61

    (3) The mold heat treatment hardness is too high

    (4) regular maintenance, 5ktimes1 tempering, 15ktimes1 tempering 30ktimes........

    Second, to prevent the problem of cracking of the die-casting mold and to improve the service life of the imported die steel, we must do the following:

    1. Die-casting molding parts (moving, fixed mold, core) heat treatment requirements: hardness should be guaranteed in HRC43~48 (materials can choose SKD61 or 8407)

    2. The mold should be fully preheated before the die casting production. Its function is as follows:

    2.1 to achieve a better thermal balance of the mold, so that the casting solidification speed is uniform and is conducive to pressure transmission.

    2.2 Maintain the fluidity of the die-casting alloy when filling, have good formability and improve the surface quality of the casting.

    2.3 Reduce the poor production in the early stage and improve the productivity of die casting.

    2.4 Reduce the heat exchange stress of the mold and improve the service life of the mold. The specific specifications are as follows:

    Alloy type aluminum alloy zinc alloy

    Mold preheating temperature (°C) 180~300150~200

    3. After the new mold is produced for a period of time, the accumulation of thermal stress is the direct cause of cracking of the mold core. In order to reduce the thermal stress, the mold core and the slider after a certain period of production should be subjected to tempering to eliminate thermal stress. specific

    The production modules that need to eliminate thermal stress are as follows:

    Mold type first tempering second tempering third tempering

    Aluminum alloy <2000 mode <10000 mode <30000 mode

    Zinc alloy <10000 mode <20000 mode <50000 mode

    Third, the 20 points that make the mold reach a long life:

    1, high quality molding materials

    2. Reasonable design of mold wall thickness and other mold dimensions

    3, try to use the last page of the insert page 4, under the possible conditions, choose the corner as much as possible R

    5. The distance between the cooling channel and the profile and corner must be large enough.

    6, after roughing should be stress tempered

    7, correct heat treatment, quenching cooling must be fast enough

    8, thoroughly polished to remove EDM enamel layer

    9, the profile can not be highly polished

    10, the mold surface should be treated by oxidation

    11, if selected nitriding, the layer should not be too deep

    12. Preheat the mold to the recommended temperature in the correct way.

    13, start to die casting 5 ~ 10 pieces should use slow hammer speed

    14. Minimize the temperature of the aluminum liquid on the premise of obtaining qualified products.

    15, do not use too high aluminum injection speed

    16, to ensure that the mold is properly cooled, the temperature of the cooling water should be maintained at 40 ~ 50 ° C

    17. Temporary shutdown, try to close the mold and reduce the amount of cooling water to avoid the thermal shock of the mold when restarting.

    18. When the model surface is at the highest temperature, the coolant should be turned off.

    19. However, there are not many spray release agents.

    20. De-stressing and tempering after a certain amount of die-casting

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