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Plastic Molding

Cause Analysis Warping and Deformation of Injection Molding

2017-07-18 14:40:15 hits: 171


The deformation, bending and twisting of the injection molded product are mainly due to the fact that the shrinkage of the flow direction in the plastic molding is larger than that in the vertical direction, so that the shrinkage rate of the workpiece is different and warped, and the injection mold is inevitably in the product Leaving a large internal stress caused by warping, which are high stress orientation caused by the deformation of the performance. So fundamentally speaking, the plastic material mold design determines the warping tendency of parts, to change the molding conditions to suppress this tendency is very difficult, and ultimately solve the problem must be from the mold design and improvement to proceed.


This phenomenon is mainly caused by the following aspects:
1. Plastic mold:


(1) the thickness of the product, the quality should be uniform.


(2) the cooling system is designed to make the mold cavity parts of the temperature uniformity, the casting system to make the flow of symmetry to avoid the flow direction, the shrinkage caused by different warping, appropriate thicker part of the more difficult to shape the mainstream, Road, try to eliminate the cavity of the density difference, the pressure difference, the temperature difference.


(3) the thickness of the product transition zone and the angle should be smooth enough, to have a good mold release, such as increased mold release margin, to improve the surface of the polishing, the top of the system to maintain balance.


(4) exhaust to be good.
(5) to increase the product wall thickness or increase the direction of anti-warping, reinforced by the reinforcement to enhance the anti-warping ability.


(6) mold used in the material rigidity.

2. Plastic raw materials:

Crystalline than non-crystalline plastic warping deformation opportunities appear more,And the crystalline plastic can be reduced with the cooling rate increases, the shrinkage of the crystallization process to correct the warping deformation.


3. Plastic processing:
(1) injection pressure is too high, the holding time is too long, the melt processing temperature is too low too fast will cause internal stress increases and warping deformation.

(2) mold temperature is too high, the cooling time is too short, so that the product when the mold overheating and top deformation.

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

(4) if necessary, easy to warp deformation of the product after the soft mold or mold removal after processing


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