16-cavity pipe blank mold

16-Cavity Parison Mold

I. Mold Definition and Product Positioning

The 16-cavity parison mold is a high-efficiency injection mold specifically designed for the high-volume production of small to medium-sized plastic packaging container preforms. Featuring an integrated layout with 16 cavities, this mold enables the simultaneous production of 16 preforms in a single injection cycle, significantly enhancing production efficiency. It serves as core production equipment in industries with large-scale packaging demands, such as cosmetics bottles, pharmaceutical bottles, and lubricant oil containers. The mold's output—parisons—are preforms for subsequent stretch blow molding, and their quality directly determines the barrier properties, clarity, and mechanical strength of the final packaging containers.

II. Core Technical Features of Mold Structure Design

1. High-Density Cavity Layout

   • Utilizes a balanced "grid" or radial circular layout to ensure nearly identical melt flow lengths and pressure drops from the main runner to each cavity.

     
     

   • Each cavity is an independent modular insert, facilitating quick replacement, individual maintenance, and adaptation to different neck finish specifications.

     
     

   
   

2. Valve-Gated Hot Runner System

   • Employs a "one-cavity-one-nozzle" valve-gated hot runner system, with 16 independently temperature-controlled hot nozzles, enabling runnerless molding with minimal gate vestige.

     
     

   • The runner system is optimized via fluid dynamics simulation to ensure rapid, balanced filling of all cavities within 0.5-1.2 seconds, effectively controlling shear heat and preventing material degradation.

     
     

   
   

3. High-Efficiency Conformal Cooling System

   • Both cores and cavities incorporate high-density conformal cooling channels, with channel spacing controlled within 8-12mm, closely following the product contour.

     
     

   • Enhanced cooling structures, such as fountain (bubbler) or spiral channels, are applied in thick-walled areas like the parison neck and base to ensure uniform cooling and shorten the cycle time.

     
     

   
   

4. Precision Demolding and Automation Integration

   • A composite demolding system combining pneumatic assistance and mechanical ejection ensures smooth, deformation-free, and scratch-free demolding of thin-walled parisons.

     
     

   • The mold structure is highly integrated with robotic part removal systems, enabling full automation of molding, part extraction, and inspection, with short mold changeover times.

     
     

   
   

III. Key Points in Molding Process and Quality Control

1. Material Compatibility: Suitable for various materials including PET, PP, and PE, especially ideal for high-speed molding of PET preforms. Raw materials require thorough drying; for PET, moisture content must be ≤0.005%.

   
   

2. Process Window:

   • Barrel Temperature: 260-285°C for PET; 200-230°C for PP.

     
     

   • Mold Temperature: 8-12°C for PET (for low-temperature, high-gloss finish); 20-40°C for PP.

     
     

   • Injection Speed: High-speed injection (fill time ≤1.5 seconds), coupled with multi-stage packing to control shrinkage.

     
     

   
   

3. Quality Control:

   • Parison Weight Variation: ≤0.15g (for PET); ≤0.3g (for PP).

     
     

   • Neck Dimension Accuracy: Key mating dimension tolerance ≤ ±0.03mm.

     
     

   • Appearance Requirements: Surface free of defects and bubbles; high clarity (for PET).

     
     

   
   

IV. Mold Materials, Lifespan, and Maintenance

1. Core Materials: Cavities/cores are made from mirror-polish stainless steels like S136 or NAK80, with hardness HRC 48-52, ensuring high polishability and wear resistance.

   
   

2. Design Lifespan: With standardized use and maintenance, it can stably produce 8 to 12 million cycles.

   
   

3. Maintenance Focus: Regular cleaning of the hot runner, checking cooling channel efficiency, lubricating moving components; preventive polishing of cavities is recommended every 50,000 to 100,000 cycles.

   
   

V. Production Integration and Market Applications

1. Injection Molding Machine Requirements: Requires clamping force ≥300 tons, shot capacity ≥500g, equipped with PET-specific screws and closed-loop control systems.

   
   

2. Production Capacity Analysis: Assuming a 12-second cycle time, daily output can reach approximately 115,000 parisons, with annual capacity exceeding 30 million pieces, suitable for centralized production in large packaging enterprises.

   
   

3. Application Industries: Widely used in the manufacture of packaging bottles for beverages, edible oils, condiments, cosmetics, pharmaceuticals, and more.

   
   

Conclusion

The 16-cavity parison mold represents the advanced level of high-efficiency, high-precision parison production, embodying concentrated multi-cavity, high-speed, and automated molding technologies. Through precise runner balancing, efficient cooling control, and stable demolding design, it achieves economies of scale in output while ensuring the high quality of individual preforms. This mold forms the cornerstone supporting the large-scale, standardized production of modern packaging industries, particularly suitable for the fast-moving consumer goods packaging sector, which demands stringent cost control, short delivery cycles, and high product consistency. As lightweighting and the use of recycled materials (rPET) become more prevalent, future mold designs will further enhance compatibility and stability for processing new materials while maintaining high efficiency.