In the field of "massive small parts" such as consumer electronics and medical consumables, production capacity of traditional molds has approached limit - production capacity ceiling of 16 cavities and 32 cavities in a single mold has been completely broken by a set of 128-cavity hot runner two-color molds. It is like a "nuclear reactor" in injection molding industry, with ability to produce 128 two-color products in a single injection molding, which improves production efficiency to dimension of Industry 4.0. But behind this system is ultimate challenge of materials, machinery, thermodynamics and intelligent control.

 

Definition
Integrate 128 cavities in a single set of molds, achieve zero waste injection molding through hot runner system, and use rotation/translation mechanism to complete two-color molding. Its core mission is to achieve the largest scale of mass production with the smallest footprint and lowest energy consumption.
Typical application scenarios
Consumer electronics: TWS headset charging contacts (copper core + plastic), SIM card tray (hard glue + soft glue);
Medical consumables: infusion three-way valve (transparent PC + color identification ring);
Food packaging: two-color bottle cap (PP sealing layer + PET decorative layer).
Performance parameters
Daily production capacity: 500,000~800,000 pieces (24-hour operation);
Scrap rate: <0.5% (traditional cold runner mold scrap rate is about 30%);
Color change time: ≤15 minutes (traditional molds take more than 2 hours).

1. Runner balance: let 128 "blood vessels" transfuse blood evenly
Challenge: After melt flows through 128 branches, pressure loss at the end can reach 60% of initial value;
Innovative solution:
Graded decompression runner: diameter of main branch runner decreases from φ12mm to φ4mm step by step;
Moldflow topology optimization: AI generates asymmetric runner layout to compensate for pressure difference;
Case: A connector company compressed weight difference of 128 cavities from ±8% to ±1.5% through optimization.
2. Hot runner temperature control: precise control of 128 "furnaces"
Difficulty: Hot runner system needs to independently control temperature of 128 nozzles (temperature difference ≤±1℃);
Black technology:
Nano heating film: replaces traditional heating ring, heating rate is increased by 3 times, and energy consumption is reduced by 40%;
Distributed PID algorithm: every 4 cavities share a temperature control module, balancing cost and accuracy.
3. Rotation mechanism: "ballet" of 5-ton mold core
Precision requirements: alignment error of 128 cavities after rotation is ≤±0.03mm;
Technical breakthroughs:
Hydraulic-servo hybrid drive: hydraulic (fast) for coarse positioning, servo (accurate) for fine positioning;
Self-compensating bearing: real-time detection of eccentric load, fine-tuning of gap through piezoelectric ceramics.
4. Cooling efficiency: a "heat dissipation maze" racing against time
Design strategy:
3D printing conformal water channel: fits product surface, shortens cooling time by 30%;
Zoned temperature difference control: mold temperature of hard glue zone is 80℃, and mold temperature of soft glue zone is 20℃ to prevent interface deformation.
5. Mold material: "Steel body" that can withstand 1 billion cycles
Selection criteria:
Mold core: ASP-60 powder steel (hardness HRC64, fatigue resistance increased by 5 times);
Slider: CERATIZIT tungsten carbide (wear resistance is 10 times higher than traditional steel);
Cost: Cost of a single set of mold materials exceeds 3 million yuan.

Cost comparison (taking an electronic contact as an example)

Hidden benefits
Reduce mold change frequency, save 1,500 hours of work per year;
One-piece molding eliminates assembly processes, and labor costs are reduced by 70%;
Increase product premium through two-color design (such as medical consumables unit price +50%).

Project Background
An international medical company produces two-color gears for insulin pens. It originally used 8-cavity molds, with a daily production capacity of less than 20,000 pieces, and relied on manual assembly, with a yield rate of only 88%.
128-cavity two-color mold solution
Mold:
64 hard glue (PEEK) + 64 soft glue (TPU) simultaneous injection molding;
Hot runner system is equipped with self-cleaning function, and material change time is ≤10 minutes.
Process:
In-mold visual inspection, real-time rejection of defective products;
Pre-embedded microcircuit on the joint surface to achieve 100% conductivity test.
Results
Daily production capacity increased to 510,000 pieces;
Quality rate jumped to 99.97%;
Cost of a single gear dropped from 0.8 yuan to 0.25 yuan.

256-cavity modular design:
Through standardized sub-module splicing, flexible expansion of production capacity is achieved;
AI dynamic compensation:
Real-time monitoring of pressure and temperature of each cavity, automatic adjustment of injection molding parameters;
Green manufacturing:
Biological-based material adaptation (such as PLA+TPU), carbon emissions reduced by 60%;
Self-healing coating:
Diamond-like carbon film (DLC) is coated on cavity surface, and service life exceeds 100 million molds.
Conclusion
128-cavity hot runner two-color mold is ultimate combination of precision manufacturing and economies of scale. It uses technology to break through physical limits, and also uses calm numbers to prove that in manufacturing industry, "quantitative change" itself is a kind of "qualitative change"