What is the difference between a two-color injection molding machine and a single-color injection molding machine?

1. Working Principle and Structural Design
Single-color injection molding machine: equipped with a single injection unit, only one color or material can be used when in use, and the production is completed by injecting molten plastic into the mold, and the operation process is simple. The product contains only one injection cavity, with a simple structure, suitable for a single material or color.
Two-color injection molding machine: equipped with two independent injection systems, which can handle two different colors or materials respectively. By rotating or translating the mold to switch positions, the product can complete two injections in the same cycle to achieve multiple color composites. The product needs to design two or more injection cavities, and consider complex issues such as sealing methods, synchronization of cooling systems, and independence of ejection mechanisms. The rear mold usually needs to be rotated or translated to ensure that the two injections are accurately docked.

2. Production process and efficiency
Single-color injection molding: It can be completed in one injection action, without changing materials or molds, with high production efficiency, suitable for large-scale standardized production. And during production, only the fluidity, shrinkage and other parameters of a single material need to be considered, and the process adjustment is relatively simple.
Two-color injection molding: Two injection moldings are required, and the temperature, pressure and material compatibility must be strictly controlled each time, but the product can be molded in one time to reduce subsequent assembly. The compatibility, melting point difference (soft glue temperature must be lower than hard glue melting point) and shrinkage of the two materials must be matched when the product is working. In addition, high melt viscosity materials must be used, and the injection pressure must be increased to cope with complex flow channel resistance.

3. Application scenarios
Single-color injection molding: Suitable for products with a single color and simple structure, such as household containers, pipes, standard parts, etc.
Two-color injection molding: Mostly used for high-value-added products that require multi-color/multi-material composites, and supports soft and hard combination, transparent/non-transparent combination, to enhance product beauty and functionality.