Plastic mold cavity core design requirements are as follows,

1. Parting surface is roughly divided into three categories: plane, inclined surface, and curved surface. Curved surface parting has the highest difficulty coefficient

1) Length of plane parting sealing section is taken according to standard, remaining planes need to avoid air to improve processing and mold matching.
2) Plane parting of deep cavity and large molds needs to design secondary positioning to increase mold positioning accuracy and prevent misalignment from causing product segmentation.

 

1) For inclined parting, an extension section is designed around product sealing position, and then stretched out, because extension section is conducive to sealing, which is convenient for mold matching and processing in later stage.
2) Locking of mold with inclined parting is easy to slip and dislocation, and mold should be designed with positioning steps to increase reliability.

 

1) When parting surface is a curved surface, it is relatively simple and smooth, and number of surfaces is reduced as processing principle. It should be convenient for later CNC processing efficiency and avoid EDM processing of parting surface as much as possible.
2) Parting at the corner is smooth, steps and sharp corners are minimized to improve processing processability of parting surface.
3) Except for necessary sealing curved surface, it must be designed to avoid air to improve processing efficiency and save costs.

 

 

Small mold (3535): 15≤L≤20
Medium mold (5055): 21≤L≤30
Large mold (greater than 5055): 30≤L≤40
Note: All surfaces except sealing surface should be kept free of air.

For molds with large cavities, secondary positioning bosses need to be designed around mold to prevent excessive injection pressure from causing mold eccentricity.

 

Angle of secondary positioning is uniformly stipulated as 10°, and positioning top surface should be kept clear of 0.5-1. Height of positioning boss should not be less than 6mm at least, boss should be increased accordingly for medium and large molds.

 

Exhaust needs to be designed at the end of parting surface and end of injection flow channel, and product must have exhaust at final filling position.
Parting surface and end of material flow are shown in figure below

 

1) Inclined parting mold needs to be designed with secondary positioning to prevent slipping and dislocation during mold closing.
2) A plane is designed at the top of inclined surface to facilitate reference data collection during processing and repair.
3) Secondary positioning design requirements: Rear mold side is close to low position of inclined surface to design a convex secondary positioning.

 

4) Design flow channel on inclined surface: Note that flow channel cannot have undercuts to avoid dislocation of front and rear mold flow channels after processing. (See red area in figure)

 

5) Inclined parting vent groove cannot have undercuts and must be perpendicular to mold opening direction.

 

 

Extended

 

Above content is basic requirements for parting, for reference only.