Medical Double-Color Plastic Injection Molding Companies

Medical Double-Color Mold Basics

Double-color molds, also called two-shot molds, create parts with two distinct colors using the same machine but with separate injections. These molds typically consist of two core halves (typically rotating 180 degrees) and a fixed cavity side. The finished part is ejected only once. Special double-color injection machines are required for this process.

Medical Injection Molding Products Key Design Considerations:

Differing Cavities, Same Core (with Exceptions): While the core (forming the inside of the part) usually maintains the same shape, the cavity shapes for each color will differ. Sliders can be incorporated if the core needs to be adjusted.
Matching and Sealing: After rotation, the cavity must precisely align with the other core half. Designers should ensure a proper seal between the core and cavity to prevent material leakage (flash).
Machine Compatibility: Double-check the machine’s specifications, including maximum and minimum mold thickness limitations, and the distance between knockout holes (K.O. holes).
Gate Design: Three-plate molds for double-color applications often require automated gating, especially for softer resins.
Scratch Prevention and Flash Control: When designing the second cavity, consider space to avoid scratching the first molded section. However, maintain a sufficient sealing area. Part deformation during molding can also cause flash. To mitigate this, you can slightly oversize the first molded section, creating a tighter fit during the second injection.
Part Deformation: Analyze the potential for the second injection to deform the first section due to resin flow. Implement solutions to prevent this if necessary.
Balanced Cooling: Ensure a balanced and ample cooling system for both mold halves.
Material Selection and Surface Texture: Prioritize injecting the harder material first, as softer materials are more prone to deformation. Consider the “stickiness” of the resins and the mold surface texture to optimize adhesion between the two colors.

By understanding these principles, designers can create successful Medical Injection Molding Products double-color injection molded parts that are both aesthetically pleasing and functional.