What is a two-color injection mold and which electronic products are suitable for it?

一, The technical essence of two-color injection molds
Dual color injection mold is a precision molding technology that achieves two material injections and one product demolding through a dedicated injection molding machine. The core lies in the collaborative innovation of mold structure and injection molding equipment: the mold adopts a dual cavity design, and the male mold (moving mold) part remains consistent, while the female mold (fixed mold) achieves two molding processes through 180 ° rotation. The injection molding machine is equipped with a twin-screw system, which can independently control the melting temperature, injection pressure, and speed of two materials, ensuring seamless fusion of materials in the mold.
Taking the middle frame of a smartphone as an example, traditional techniques require a visual transition between metal and plastic through spraying, while dual color injection molding technology can directly co inject metal powder with PC/ABS plastic to achieve seamless connection between mirror high gloss and frosted texture while maintaining structural strength. This process not only eliminates post-processing steps, but also increases the product yield from 75% of traditional processes to over 92%.
二, Core application scenarios in the field of electronic products
1. Consumer Electronics: Dual Evolution of Touch and Vision
Phone buttons and casing: Made of PC hard rubber as the substrate, TPU soft rubber as the functional area cover, and integrated with anti slip patterns and hard borders through dual color injection molding. The side buttons of Huawei Mate series smartphones adopt this technology, with a lifespan of over 1 million times and maintaining IP68 waterproof performance.
Wireless earphone charging case: TPE soft rubber is injected into the inner layer of the PC shell to enhance grip comfort and reduce drop damage rate through the cushioning effect of the soft rubber. The interior of the Apple AirPods Pro charging case adopts this technology, allowing the product to pass a 1.5-meter drop test.
Smart watch strap: Combining silicone and TPU through dual color injection molding, the outer layer of silicone provides a skin friendly touch, while the inner layer of TPU enhances support. After applying this technology to the Xiaomi Watch S3 strap, the wearing comfort score has increased by 40%, while the tensile strength has increased by 25%.
2. Automotive Electronics: Integration of Functional Safety and Aesthetic Design
Car display screen frame: Adopting dual color injection molding of PC/ABS hard glue and PMMA transparent material, achieving a balance between narrow frame design and high transparency. After applying this technology to the central control screen frame of Tesla Model 3, the screen to body ratio increased to 89%, and it passed extreme temperature tests ranging from -40 ℃ to 85 ℃.
Steering wheel button module: Through the dual color molding of PA66 hard rubber and TPE soft rubber, a micro textured tactile layer is formed on the surface of the buttons to improve blind operation accuracy. After adopting this technology, the misoperation rate of the steering wheel buttons in the Mercedes Benz S-Class has been reduced by 60%.
Car charger shell: Combining fire-resistant PC with TPU soft rubber, the outer hard rubber provides structural support, and the inner soft rubber achieves anti slip insertion and removal. After applying this technology, the Anker PowerDrive series car charger has a plug-in life of over 20000 times and has passed the UL94 V-0 fire certification.
3. Medical Electronics: Breakthroughs in Biocompatibility and Precision Structures
Blood glucose meter housing: Made of dual color injection molding of medical grade PP hard rubber and TPE soft rubber, the outer hard rubber provides a sterile surface, and the inner soft rubber achieves anti slip grip. After applying this technology, the Roche Excellence blood glucose meter has improved user grip stability by 50% and has also passed ISO 10993 biocompatibility certification.
Endoscope handle: Through dual color molding of PC/ABS and silicone, conductive silicone buttons are embedded in key operating areas to achieve a balance between IP67 waterproof and precise touch control. After adopting this technology, the Olympus EVIS X1 endoscope handle has reduced the response time to 0.2 seconds.
Portable ultrasonic probe: co injection molding of high-strength engineering plastic and acoustic matching layer material, achieving improved acoustic transmission efficiency while maintaining the structural strength of the probe. After applying this technology, the Mindray M9 portable ultrasound probe achieved a 15% increase in image resolution and passed a 1-meter drop test.
三, Technological advantages and industry trends
1. Dual optimization of efficiency and cost
The two-color injection mold replaces the traditional secondary encapsulation process with a one-time molding, reducing the production cycle by 40% -60%. Taking the Xiaomi 10 phone frame as an example, after adopting dual color injection molding, the single piece production cost has been reduced from 12.5 yuan to 8.3 yuan, while reducing the VOCs emissions caused by the spraying process.
2. Collaborative enhancement of material properties
Through the composite design of soft and hard adhesives, the product can simultaneously possess high strength and flexibility. The Lenovo ThinkPad X1 Carbon laptop shaft adopts dual color injection molding of PC/ABS and TPE, which can withstand 50000 opening and closing tests while achieving 180 ° flat function.
3. Environmental Protection and Sustainability
The dual color injection molding technology reduces surface treatment processes such as spraying and electroplating, resulting in a reduction of over 90% in VOCs emissions from the product. After applying this process to the shell of Dell Latitude 5000 series laptops, it has passed the EPEAT Gold Environmental Certification, reducing its carbon footprint by 35%.
4. Industry development trends
With the popularization of technologies such as 5G and the Internet of Things, the demand for lightweight and integrated electronic products is becoming increasingly urgent. Dual color injection molds are developing towards multi material and multi-color direction. For example, the Samsung Galaxy Z Fold series folding screen mobile phone hinge has adopted a composite injection molding process of three materials: PC/ABS, PA66, and TPE, achieving a perfect balance between structural strength and flexibility.