The Design of The Dustbin Mould Determines The Warpage Tendency

  • Fundamentally, the design of the Dustbin Mould(FURNITUREMOULD) determines the warpage tendency of the part. It is difficult to suppress this trend by changing the moulding conditions. Finally, the problem must be solved through mould design and improvement. This phenomenon is mainly caused by the following aspects:

    Mould aspect:

    (1) The thickness and quality of the parts should be uniform.

    (2) The design of the cooling system is to make the temperature of each part of the cavity uniform. The pouring system should make the flow symmetry, avoid the warpage caused by different flow directions and shrinkage, and it is difficult to form part of the shunting channel and the mainstream. Road, try to eliminate the density difference, pressure difference, temperature difference in the cavity.

    (3) The transition zone and corner of the workpiece should be sufficiently round and have good release properties, such as increasing the mould release margin and improving the polishing of the die face. The ejector system should be balanced.

    (4) The exhaust should be very good.

    (5) Increase the wall thickness of the part or increase the anti-warpage direction, strengthen the ribs, and enhance the anti-warping ability of the parts.

    (6) The strength of the materials used in the dustbin mould is insufficient.

    2. Plastic:

    The crystal type has a greater chance of warpage deformation than the amorphous plastic, and the crystal type plastic can correct the warpage deformation by using a crystallization process in which the crystallinity decreases as the cooling rate increases and the shrinkage ratio becomes small.

    3. Processing:

    (1) The injection pressure is too high, the holding time is too long, and the melting temperature is too low. The speed is too fast, causing internal stress to increase and warp.

    (2) The temperature of the dustbin mould is too high, the cooling time is too short, the parts during demolding are overheated, and spray deformation occurs.

    (3) Reduce the screw speed and back pressure to reduce the density while maintaining the minimum charge amount to limit the generation of internal stress.

    (4) If necessary, the mould may be soft or demolded after the dustbin mould is easily warped and deformed.

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