This article provides an overview of the characteristics associated with the secondary injection molding process in vertical injection molding machines. Soft plastic structures are typically utilized for aesthetic components and feature relatively simple designs. When designing these parts, it is essential to adhere to six key standards related to plastic machine design: wall thickness, draft angle, product connection requirements, material bonding, mold locking mechanisms, and measures to prevent debonding and shrinkage.
1.Wall Thickness Requirements:
For soft plastic components in general electronic products, the typical thickness ranges from 2 to 3 mm. In areas where structural constraints exist, the design should ensure that the thickness does not fall below 1 mm or exceed 4 mm.
2.Draft Angle Requirements:
During the design phase, a draft angle of approximately 1° larger than that of hard plastics is recommended. The necessary draft angle varies with material strength; materials with higher strength require smaller angles, while those with lower strength necessitate larger angles. Additionally, the draft angle is influenced by the surface texture of the product—coarse textures require larger angles, while fine textures require smaller ones.
3.Product Corner Requirements:
To maintain uniform thickness and prevent stress concentrations at corners, which could compromise the product’s compressive strength, it is crucial to ensure consistency in the design.
4.Material Bonding Requirements:
Demolding hooks may be incorporated into the overall design to facilitate the removal of soft plastics. It is advantageous to maximize the bonding area between hard and soft plastics.
5.Mold Locking Mechanism Requirements:
It is important to prevent burrs that can arise from the edges of soft plastic during molding by adhering to established standards for mold locking mechanisms.
6.Defect Management:
The design process should consider the potential location and severity of defects, aiming to minimize them or reposition them to primary or secondary surfaces. To mitigate issues like debonding and dehydration of soft plastics, the demolding structure should be thoughtfully designed at the interface of the two materials while striving to maximize the bonding area.
By following these guidelines, the secondary injection molding process can be optimized for better performance and product integrity in vertical injection molding applications.
