A 3GL Preform Mold (3-Gallon Preform Mold) is a high-precision injection mold used to produce preforms specifically for 3-gallon (approximately 11.36-liter) plastic containers (primarily PC/PET water bottles). This mold shapes plastic raw material into tubular preforms via the injection molding process, which are later expanded into the final containers through blow molding.
Item | Typical Parameters |
|---|---|
Capacity Specification | 3 Gallons (≈11.36 Liters) |
Preform Material | PC (Polycarbonate) or PET (Polyethylene Terephthalate) |
Preform Weight | 60–90 grams (depending on wall thickness design) |
Number of Cavities | Common: 1-cavity, 2-cavity, 4-cavity (affects production efficiency) |
Molding Cycle Time | 25–40 seconds (depends on cooling system efficiency) |
Service Life | 1–3 million cycles (depends on steel quality and maintenance) |
Hot Runner System
Utilizes multi-point valve-gate hot runners to ensure uniform melt filling.
Reduces sprue waste and improves raw material utilization.
Optimized Cooling System
Spiral cooling channel design ensures uniform cooling of preform walls.
Independent zone temperature control reduces cycle time.
Venting and Ejection Design
Precision venting slots prevent air traps and burn marks.
Hydraulic synchronous ejection mechanism ensures smooth preform release.
Steel Selection
Core/Cavity: Swedish ASSAB 8407 (H13-type) pre-hardened mold steel.
Surface Treatment: Nitriding/PVD coating to enhance wear and corrosion resistance.
Key Control Points:
Injection Temperature: PC 280–320°C / PET 260–290°C
Mold Temperature: 80–110°C (PC), 8–12°C (PET crystallization control)
Precise control of back pressure and holding pressure to prevent shrinkage deformation.
Inspection Item | Allowable Tolerance | Inspection Method |
|---|---|---|
Total Preform Weight | ±0.5 grams | Electronic Scale |
Neck Inner Diameter | ±0.05 mm | Projector / Caliper |
Wall Thickness Uniformity | ≤0.15 mm deviation | Ultrasonic Thickness Gauge |
Thread Integrity | No flash, short shots | Visual Inspection |
Main Application Fields
✅ Bottled Water Industry (for home/office water dispensers)
✅ Industrial Liquid Packaging (chemicals, food ingredients)
✅ Agricultural Irrigation Water Storage Containers
Technology Development Trends
Multi-Cavity & High Efficiency: Molds with 4+ cavities to increase per-cycle output.
Intelligent Integration: Equipped with sensors for real-time monitoring and predictive maintenance.
Lightweight Design: Structural optimization reduces preform weight by 5–10%, saving material costs.
Quick Mold Change Systems: Adapt to small-batch, multi-variety production needs.
Production Requirement | Recommended Configuration |
|---|---|
Small-Batch Trial Production | 1-cavity mold (low investment cost) |
Medium-Scale Production | 2-cavity mold (balances efficiency and cost) |
Large-Scale Continuous Production | 4-cavity+ mold with fully automated hot runner system |
Daily Maintenance: Clean parting surfaces and lubricate guide pillars per shift.
Periodic Maintenance: Inspect hot runner nozzle wear and water channel scaling every 50,000 cycles.
Lifecycle Management: Maintain mold records and track replacement cycles for key components (e.g., ejector pins, seals).
Conclusion: The 3GL preform mold is a core piece of equipment bridging injection and blow molding processes. Its design precision and stability directly determine the final container's sealability, pressure resistance, and appearance quality. With increasing environmental requirements, modularity, low energy consumption, and long service life have become key directions for the evolution of such molds.