Reasons For Cracking Of Injection Molded Products

- Jul 24, 2018-

3. Mold aspect


(1) The balance should be balanced. For example, if the number of ejector pins and the cross-sectional area are sufficient, the draft angle should be sufficient, and the cavity surface should be sufficiently smooth to prevent cracking due to external force causing residual stress concentration.

(2) The structure of the workpiece should not be too thin, and the transition part should adopt the arc transition as much as possible to avoid stress concentration caused by sharp corners and chamfers.

(3) Minimize the use of metal inserts to prevent the internal stress from increasing due to the difference in shrinkage between the insert and the part.

(4) Appropriate stripping intake passages shall be provided for deep-bottomed parts to prevent vacuum underpressure.

(5) The main channel is large enough to release the gate material in the future when it is cured, so that it is easy to demould.

(6) The main channel bushing and the nozzle joint should prevent the chilled material from being dragged to make the workpiece stick to the fixed mold.


4. Machine side


The plasticizing capacity of the injection molding machine should be appropriate. If the plasticization is too small, it will not be completely mixed and become brittle. When it is too large, it will degrade.