Views: 0 Author: Site Editor Publish Time: 2026-07-21 Origin: Site
In recent years, foldable smartphones have broken out of niche markets, with inner-folding, outer-folding, vertical-folding and triple-folding models mushrooming across the industry. Slim body design, minimal fold creases, and stable structure without looseness after hundreds of thousands of folds have become the core metrics for judging foldable device quality. The hinge is the critical component that delivers a premium folding experience, and MIM (Metal Injection Molding) technology lays a solid foundation for mass production of lightweight, ultra-precise and long-service-life foldable hinges.
Three Major Manufacturing Challenges of Foldable Display Hinges
A foldable hinge is a miniature precision system integrating transmission, support and damping functions, bringing extreme manufacturing difficulties.
First, the trade-off between ultra-thin profile and structural strength: core components feature wall thickness less than 0.5 mm, yet must withstand over 200,000 repeated folding cycles without deformation or loose fittings.
Second, stringent assembly precision requirements: dozens of micro gears, cams and rotating shafts are nested inside the hinge, with dimensional tolerances controlled within ±0.01 mm.
Third, bottlenecks in mass production via conventional processes: CNC machining delivers a material utilization rate below 5%, while stamping and casting struggle to balance precision and ductility. MIM technology perfectly solves all these drawbacks.
Working Principles of the MIM Process
Metal Injection Molding (MIM) is a hybrid technology combining plastic injection molding and powder metallurgy. Metal powder is proportionally blended with binders and pelletized, followed by four core production stages:
1. Injection Molding: Molten raw materials are injected into molds under high pressure to form complex irregular structures in a single forming cycle.
2. Debinding & Purification: Binders are fully removed to retain a pure metallic green body skeleton.
3. High-Temperature Sintering: Powder particles fuse together under vacuum conditions, significantly boosting material hardness and toughness.
4. Precision Post-Treatment: Grinding and coating processes are applied to limit surface roughness to Ra ≤ 0.4 μm.
MIM Technology Reinvents Foldable Hinge User Experience
At present, MIM technology has a penetration rate exceeding 75% for core hinge components, and flagship hinges from Huawei, Samsung and Honor all adopt this process. MIM elevates user experience in four key aspects:
1. Breaking structural constraints: It enables the fabrication of intricate thin-walled structures thinner than 0.5 mm, facilitating slimmer and lighter device bodies.
2. High strength and wear resistance: Components feature dense, pore-free internal textures with deformation resistance up to 1900 MPa.
3. Micron-level precision: Perfect meshing of dozens of micro components delivers smooth, consistent damping feedback during folding.
4. Cost reduction and efficiency improvement: With a nearly 98% material utilization rate, MIM has driven foldable devices down from premium price points above 10,000 yuan to mid-range price segments.
Conclusion
As new products such as triple-fold displays and scrollable screens emerge, MIM processes keep iterating through optimized powder particle sizes and upgraded binder systems. It can be said that the widespread popularization of foldable devices among consumers would not have been achievable without the mature commercialization of MIM technology. In the future, MIM technology will further expand its applications in high-end sectors including smart wearables and humanoid robot joints, continuously fueling innovative advancements in precision manufacturing.
