Project Background
The client is a well-known mobile phone accessory brand planning to launch a high-end series of phone cases. They wanted to achieve a combination of hard and soft materials, anti-slip and wear-resistant properties, and a differentiated appearance through a two-shot injection molding process. Traditional single-color injection molding could not meet their requirements for feel and appearance. They chose GBM to develop a two-shot mold to achieve a high-quality phone case produced in one piece.
Our Solution
1. Mold Design and Structural Optimization
The GBM engineering team adopted a rotary two-shot mold design. For the first injection, we injection molded a rigid PC shell. Subsequently, we performed a second TPE overmolding injection on the same machine. The mold uses a high-precision guiding and positioning system. Precise alignment between the two injections ensured no misalignment or overflow between the two materials.
2. Material Selection
For the first injection, we chose PC (polycarbonate). The second injection material is TPE soft rubber. The two materials ensure the structural strength and impact resistance of the phone case, while also improving anti-slip performance and grip feel. GBM ensures strong adhesion and consistent color after formula testing of the two materials.
3. Machining and Process Control
Mold parts are machined using high-precision CNC machining and wire EDM, with tolerances controlled within ±0.005mm for key areas. Temperature and injection speed are strictly controlled during injection molding to achieve a seamless bond between the two materials.
4. Appearance and Production Efficiency Optimization
Mirror polishing and texturing processes are used on the mold surface to meet customer appearance requirements. Optimization of the runner and cooling system reduces the molding cycle by 15%, resulting in excellent product appearance consistency.
Project Results
- Mold Manufacturing Cycle: 35 days
- First-time Trial Success Rate: 98%
- Mold Life: Over 600,000 cycles
- Product Adhesion Strength: Passed thermal shock and drop tests
- Appearance Acceptance Rate: 99.5%
The customer is very satisfied with the two-color injection molding results. They stated that GBM has reached international top-tier standards in mold precision, cycle control, and surface treatment.
