As the core equipment for achieving an ultra-high production rate of 2,000 pieces per minute (approximately 33 pieces per second), the design and application of a 64-cavity high-speed mold are more than simply increasing the number of cavities; rather, they are the result of precision engineering and system optimization.
1. Precision Hot Runner System
A 64-cavity mold must utilize a zoned hot runner system (such as a 4-zone or 8-zone system), with each zone equipped with an independent precision valve pin. This, through sequential or differential control, significantly reduces the instantaneous peak pressure demand of the injection molding machine, ensuring smooth injection of high melt flows.
The runner interior must be mirror-polished, and all corners must feature wide-radius transitions to eliminate melt stagnation and degradation points. Critical areas (such as the valve pin seat and gate bushing) must be constructed of high-hardness, wear-resistant alloy steel (such as powder metallurgy steel) to withstand extremely high injection cycle times.
2. High-Speed Mold Structure
A 64-cavity mold must withstand the significant inertial impact of high-speed mold opening and closing (cycle times <1.8 seconds). We must utilize thickened mold plates (especially the B plate), heavy square iron, multi-point support pillars (SPP), and precision guide pin and bushing systems (such as needle bearing types) to ensure mold plate deformation (<0.02mm) is within acceptable limits and protect the precision mold core.
A production capacity of 2,000 caps per minute requires extremely short cooling times for bottle caps (typically <1.0 second). Cooling channel design is crucial for success. During design, the distance between the cooling channel and the cavity surface must be strictly controlled within 1.2-1.5 times the channel diameter (e.g., for an 8mm diameter channel, the distance is approximately 9-12mm).
During mold design, we carefully calculate and optimize the channel diameter, circuit design, and coolant flow rate (>2.5m/s) to ensure a high Reynolds number (>4,000) to generate turbulent flow, which significantly improves heat transfer efficiency.
3. Matching High-Speed Automation and System Integration
The mold requires an ultra-high-speed ejection system. In addition to the traditional mechanical ejection system (ejector pin/push plate), a high-response air valve-controlled air ejector pin is integrated. Synchronous action occurs at the moment of mold opening, "blowing" the bottle cap off the mold core in milliseconds, significantly reducing ejection stroke and time.
Once the mold is in place, it needs to be paired with an ultra-high-speed injection molding machine. The ultra-high-speed machine's plasticizing capacity (>1000g/s PET) and injection speed (>500mm/s) must meet the high flow requirements of 64 cavities.
