A Guide To Two-Color Injection Molding

Two-color injection molding, also known as two-shot or bi-color molding, is an advanced manufacturing process that integrates two different materials or colors into a single plastic component in one production cycle. This technology results in products with enhanced functionality, aesthetic appeal, and structural integrity.

Process of two-color injection molding  

The process involves two key stages using a dual-barrel injection machine and a rotary mold system.

First Shot: The primary material (e.g., rigid plastic like PC/ABS ) is injected into the first cavity of the mold, forming the base structure.

Second Shot: The mold rotates (typically 180°) or slides to align the partially formed part with a second cavity. A secondary material (e.g., soft TPE or a contrasting color) is then injected, bonding with the first layer to create a unified component.

Key Advantages

Enhanced Aesthetics & Functionality: Create soft-grip handles (hard plastic + TPE), light-transmitting buttons (opaque + transparent resin), or waterproof seals without secondary processes

Cost & Time Savings: Consolidates molding, assembly, and decoration into one cycle, cutting labor by 30–50%

Structural Superiority: Achieves stronger material bonding than overmolding since substrates bond while semi-molten, reducing failure risks

Material Compatibility for Two-Shot Injection Molding

 Not all plastics bond well during two-color injection molding. You must choose materials with chemical compatibility and similar melt temperatures.

 Common pairings ：

ABS+TPE for soft-touch handles;

PC+TPU for consumer electronics;

PP+PP( colored) for two-color storage bins;

PA6+PA6 GF for Structural housings with flexible seals;

PMMA+PMMA (transparent+colored) for Automotive lighting lenses.  

Industrial applications

Consumer Electronics: Game controllers, earbuds, remote housings 

 Automotive:  Seamless taillights (red/clear lenses) and multi-tone steering wheels

Medical: Sealed enclosures for surgical devices (PC + silicone)

Consumer Goods:  Toothbrushes (hybrid rigid/soft zones) and decorative bottle caps with marble-like pattern

Home Appliances: Blender buttons, knobs, dials

Tools & Hardware: Power tool grips, screwdriver handles

Is two-color molding right for your project?

This technology shines for complex, high-volume products requiring. But for simpler, low-volume runs, traditional molding or overmolding may be more economical.

 Contact us for a feasibility analysis tailored to your part geometry, material, and volume needs.