Precision 2K Injection Mold for Smart Wearable Accessories

Challenge 

Compact smart wearable components—such as TWS earphone charging cases and smartwatch protective bumpers—require integrated rigid housings with soft, shock-absorbing sealing edges. Traditional manual assembly of silicone gaskets suffers from inconsistent alignment, high labor costs, and fluid leakage risks. Achieving robust chemical bonding between PC+ABS rigid substrates and soft TPE/TPU overmolding within a single high-speed molding cycle presents major tooling and processing challenges.

Solution

To deliver seamless multi-material integration and structural sealing, Vios engineered a high-precision rotary 2-shot (2K) injection mold:

Precision Rotary Core Indexing: Developed a dual-station rotary plate system with balanced hydraulic clamping to ensure perfect alignment during second-shot TPU overmolding.

Optimized Thermal Interfacial Bonding: Customized mold temperature zoning to control interfacial melt temperatures, promoting strong molecular adhesion without thermal deformation of the PC+ABS base shell.

Micro-Flash Cutoff Design: Machined sharp, durable shut-off steel edges to restrict soft resin flow, preventing micro-flashing on functional sealing lips and button areas. 

Results

- IPX7 Waterproof Seals: Achieved consistent 100% sealing integrity across the overmolded sealing lip, passing IPX7 immersion tests directly out of the mold.

- 100% Manual Assembly Elimination: Replaced secondary glue-bonding and gasket placement, reducing overall product assembly cycle time by 30%.

- High Molecular Peeling Strength: Reached an interfacial peel strength exceeding 35 N/cm, preventing TPU delamination during long-term drop and flexing use.