Design and Operational Analysis of a 1.8L Hollow Extrusion Blow Molding Machine for Packaging Applications

This paper presents a comprehensive study on the design, operational principles, and performance characteristics of a 1.8-liter hollow extrusion blow molding machine. Widely employed in the production of plastic containers for beverages, personal care products, and household chemicals, the 1.8L capacity machine represents a critical segment in mid-volume packaging manufacturing. The study examines key components—including the extruder, die head, parison control system, mold assembly, and hydraulic/pneumatic systems—and evaluates their integration to achieve consistent wall thickness, dimensional accuracy, and material efficiency. Experimental data from prototype trials demonstrate the machine’s capability to produce high-quality PET and HDPE bottles with cycle times under 8 seconds and material savings of up to 12% through advanced parison programming. The findings underscore the importance of precise temperature control, synchronized clamping force, and real-time feedback mechanisms in optimizing production efficiency and product reliability.

Keywords: Blow molding; Extrusion blow molding; 1.8L bottle; Parison control; Plastic packaging; HDPE; PET

1. Introduction
Extrusion blow molding (EBM) is a dominant manufacturing process for producing hollow plastic parts, particularly containers ranging from small medical vials to large industrial drums. Among these, the 1.8-liter (approximately 60 oz) bottle size has gained significant market traction due to its ideal balance between portability and content volume—commonly used for juices, liquid detergents, and edible oils. This paper focuses on a dedicated 1.8L hollow extrusion blow molding machine, analyzing its mechanical architecture, control strategies, and performance metrics in industrial settings.

2. Machine Configuration and Working Principle
The 1.8L EBM machine operates through a cyclic sequence:

1. Extrusion: Thermoplastic resin (typically HDPE or PP) is melted and extruded through an annular die to form a tubular parison.
2. Parison Formation: The parison length and thickness profile are precisely controlled via servo-driven mandrel positioning.
3. Mold Clamping: A two-part metal mold closes around the parison.
4. Inflation: Compressed air (typically 25–40 psi) inflates the parison against the mold cavity.
5. Cooling & Ejection: The molded part is cooled by internal air and external water channels before ejection.

Key subsystems include:

• A single-screw extruder (L/D ratio: 24:1)
• Accumulator-head die for consistent parison delivery
• Servo-hydraulic clamping unit (clamping force: ~150 tons)
• Programmable logic controller (PLC) with HMI interface

3. Design Considerations for 1.8L Bottles
Producing 1.8L containers demands careful attention to:

• Wall Thickness Distribution: Achieved via dynamic parison programming to reinforce base and shoulder regions.
• Material Selection: HDPE offers chemical resistance and impact strength; PET provides clarity and barrier properties (though typically processed via injection stretch blow molding).
• Cycle Time Optimization: Target cycle time of 7–9 seconds requires rapid mold cooling and efficient take-out mechanisms.

4. Performance Evaluation
A prototype machine was tested over 500 cycles using HDPE (MFI = 0.3 g/10min). Results showed:

• Average cycle time: 7.6 s
• Weight variation: ±1.2%
• Burst pressure: >200 kPa
• Material utilization efficiency: 88.5%

Advanced features such as infrared pre-heating of the parison and closed-loop pressure regulation contributed to reduced scrap rates (<1.5%).

5. Industrial Applications and Market Relevance
The 1.8L format aligns with consumer preferences in North America and Asia for bulk beverage and cleaning product packaging. Its compatibility with automated filling lines and recyclability enhances sustainability credentials. Future developments may integrate IoT-enabled predictive maintenance and AI-driven quality inspection.

6. Conclusion
The 1.8L hollow extrusion blow molding machine represents a mature yet evolving technology that balances productivity, cost-efficiency, and product quality. Through optimized mechanical design and intelligent process control, it continues to meet the growing demand for reliable mid-capacity plastic containers in global markets.