The application of two-color injection molding in the medical field

In the rapidly advancing era of medical technology, medical devices are moving toward miniaturization, precision, and 

functional integration. Two-color injection molding, an advanced plastic molding process, has emerged as a key technical 

support in healthcare, breaking traditional limitations by precisely fusing two materials with distinct properties in a single 

molding cycle. This innovation significantly enhances product performance and production efficiency, driving transformative 

changes in medical manufacturing.

Ⅰ. Process Principles of Two-Color Injection Molding

Two-color injection molding utilizes specialized machines with dual barrels to sequentially inject two different plastics into 

the same mold cavity within one cycle. Molds typically employ turntable or core-rotating designs: after the first material forms 

the base structure, the mold rotates 180° with 0.01mm precision, aligning the semi-finished part for the second injection. This 

molten-state bonding achieves molecular-level adhesion. The process demands extreme precision, with temperature control 

within ±1℃ and pressure fluctuations under ±2bar to ensure uniform material distribution.

Ⅱ. Unique Advantages in Medical Applications

(1) Superior Functional Integration

Material Complementarity: Minimally invasive catheter connectors combine PEEK (withstanding 134℃ steam sterilization ≥100 

cycles) and silicone (liquid leakage ≤0.01ml/min) for durability and seal integrity.

Specialized Functionality: Infusion pump panels use PMMA/PC composites—transparent PMMA ensures touch sensitivity ≤0.1s, 

while PC provides impact resistance ≥20kJ/m².

(2) Reliability Under Strict Hygiene Standards

Reduced Bacterial Risks: One-piece molding eliminates assembly gaps, lowering infection risks. Insulin pen buttons, for example, 

avoid contamination from multi-step processes.

Efficient Cleaning: Smooth, seamless surfaces reduce cleaning time by 30% compared to traditional assemblies, facilitating thorough 

disinfection.

(3) Production Efficiency and Cost Control

Shorter Cycles: Medical components see ≥42% reduction in production time versus traditional assembly.

Lower Costs: Defect rates drop ≥60% by eliminating assembly errors, reducing material waste and labor expenses.

Ⅲ. Typical Medical Applications

Minimally Invasive Devices: Catheters with soft outer layers and rigid inner cores; surgical instrument handles combining rigid structures 

with TPE grips for precision.

Wearable Devices: Fitness monitors use durable outer shells with skin-friendly inner layers, integrated with waterproof display frames.

Consumables: Syringe plungers with rubber-tipped seals and rigid handles; dental trays pairing supportive frameworks with comfort layers.

Ⅳ. Challenges and Future Trends

Challenges: Material compatibility issues (e.g., bonding PEEK and silicone) require specialized compatibilizers. Precision molds cost 3-5x 

more than standard versions.

Trends: Smart systems with real-time parameter adjustment via AI and sensors; integration with 3D printing for complex components; 

bioresorbable material combinations meeting EU medical standards.

Two-color injection molding continues to revolutionize medical manufacturing, balancing performance, safety, and efficiency. Despite 

challenges, ongoing advancements promise broader applications in next-generation healthcare solutions.