Automatic PET Bottle Blowing Machine: Technical Deep Dive into Modern Blow Molding
The automatic PET bottle blowing machine transforms plastic preforms into finished containers through precisely controlled heating and stretching processes. Understanding the technical principles behind stretch blow molding helps production managers optimize output quality and troubleshoot common issues. This examination covers the core mechanisms, critical parameters, and performance benchmarks that define modern bottle blowing technology.
How Stretch Blow Molding Actually Works
PET stretch blow molding occurs in two distinct phases: preform heating and blow forming. Each stage involves specific temperature and pressure parameters that determine final bottle quality.
Preform Heating Stage
Infrared heating systems bring preforms to optimal forming temperature. Testing data (TEST-002) from ipack‘s blow molding center established these benchmarks:
- Body temperature target: 103-107°C
- Neck temperature maintenance: 45-50°C (prevents deformation)
- Temperature consistency: ±2°C across preform surface
- Wall thickness uniformity achieved: ±0.05mm
The neck region must remain below softening temperature to preserve thread integrity for cap sealing. Differential heating between body and neck zones is fundamental to successful bottle formation.
Blow Forming Stage
Once heated, preforms transfer to mold stations where mechanical stretching and air pressure create the final shape:
- Pre-blow pressure: 8-12 bar (initial expansion)
- Final blow pressure: 25-40 bar (detail formation)
- Stretch rod speed: 1.2-1.8 m/s
- Total cycle time: 1.5-3 seconds depending on bottle size
The stretch ratio—typically 10-15x longitudinal and 3-5x radial—determines material distribution and bottle strength characteristics.
Cavity Configuration and Production Capacity
Automatic bottle blowing machines scale through cavity multiplication. Each cavity operates as an independent forming station within the synchronized system:
| Cavity Count | Typical Output (BPH) | Application Range |
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