The stretch blow molding sequence commences with the preform’s transfer to the stretching station after achieving its glass transition temperature (typically 90-120°C). Here, servo-driven stretch rods perform axial elongation while blow pins induce radial expansion, inducing biaxial molecular orientation within the PET matrix. This polymer chain alignment enhances:
Tensile strength by 200-300%
Clarity through reduced crystallinity
Barrier properties against oxygen permeation
Subsequent high-pressure air injection (25-40 bar) expands the conditioned preform against water-cooled steel molds (maintained at 10-15°C), where rapid solidification locks in the bottle geometry before automated ejection.
2. Equipment Architecture Overview
Advanced PET blow molding systems integrate five core subsystems:
Plasticizing Unit: Twin-screw extruders with grooved barrels ensure homogeneous melt mixing
Hydraulic System: Proportional valves with linear guide rails enable 0.01mm positioning accuracy
Drive Mechanism: Frequency-controlled gear reducers maintain ±1% speed consistency
Control Interface: HMI-PLC systems with multi-language support for real-time process monitoring
Mold Clamping: Three-point central locking with hydraulic decompression for balanced 200-ton clamping force
These features collectively achieve cycle times as low as 4 seconds with wall thickness variation below ±5%.
3. Production Flexibility Analysis
While single-stage systems integrate preform injection and blowing in-line, two-stage configurations offer strategic advantages:
Preform Inventory Management: Stored preforms enable demand-responsive production
Energy Optimization: Separate injection/blowing units allow independent idle modes
Material Versatility: Compatibility with recycled PET (rPET) blends requiring distinct processing parameters
Modern machines incorporate predictive maintenance algorithms and IoT connectivity to further enhance operational efficiency in both configurations.
Taizhou Fupusi Machinery China Johntao@Fupusi.com +86 186 6862 7050
- Technical Material Science Perspective
Polyethylene terephthalate (PET), a synthetic polyester polymerized from ethylene glycol and terephthalic acid (molecular formula: [C10H8O4]n), exhibits exceptional material characteristics for packaging applications. Its semi-crystalline structure provides:
Barrier Performance: Oxygen transmission rate <0.5 cc·mm/(m²·day·atm)
Thermal Resistance: Vicat softening point of 160°C enabling hot-fill applications
Optical Clarity: Haze values <1% comparable to glass
These intrinsic properties enable PET containers to maintain product integrity while meeting modern sustainability requirements through multiple recycling cycles.
- Consumer-Centric Product Benefits
For bottled water applications, PET delivers a triple advantage:
Structural Reliability: With tensile strength of 55-75 MPa, bottles withstand 6-bar internal pressures
Visual Appeal: 90% light transmittance enhancing shelf presence
Circular Economy: Post-consumer PET (rPET) can achieve up to 30% recycled content without performance degradation
The material’s ability to balance functionality (leak-proof seals) with aesthetics (crystal-clear appearance) has established PET as the preferred choice for 70% of global beverage packaging.
- Lifecycle Environmental Analysis
PET’s environmental profile demonstrates:
End-of-Life Solutions: Mechanical recycling yields 100% reusable flakes
Carbon Footprint: 30% lower than glass alternatives in LCA studies
Resource Efficiency: 30% thinner walls compared to HDPE containers
The material’s closed-loop potential aligns with EU’s Single-Use Plastics Directive, positioning PET as transitional solution toward circular packaging systems.
- Technical Process Description
The stretch blow molding sequence commences with the preform’s transfer to the stretching station after achieving its glass transition temperature (typically 90-120°C). Here, servo-driven stretch rods perform axial elongation while blow pins induce radial expansion, inducing biaxial molecular orientation within the PET matrix. This polymer chain alignment enhances:
Tensile strength by 200-300%
Clarity through reduced crystallinity
Barrier properties against oxygen permeation
Subsequent high-pressure air injection (25-40 bar) expands the conditioned preform against water-cooled steel molds (maintained at 10-15°C), where rapid solidification locks in the bottle geometry before automated ejection.
- Equipment Architecture Overview
Advanced PET blow molding systems integrate five core subsystems:
Plasticizing Unit: Twin-screw extruders with grooved barrels ensure homogeneous melt mixing
Hydraulic System: Proportional valves with linear guide rails enable 0.01mm positioning accuracy
Drive Mechanism: Frequency-controlled gear reducers maintain ±1% speed consistency
Control Interface: HMI-PLC systems with multi-language support for real-time process monitoring
Mold Clamping: Three-point central locking with hydraulic decompression for balanced 200-ton clamping force
These features collectively achieve cycle times as low as 4 seconds with wall thickness variation below ±5%.
- Production Flexibility Analysis
While single-stage systems integrate preform injection and blowing in-line, two-stage configurations offer strategic advantages:
Preform Inventory Management: Stored preforms enable demand-responsive production
Energy Optimization: Separate injection/blowing units allow independent idle modes
Material Versatility: Compatibility with recycled PET (rPET) blends requiring distinct processing parameters
Modern machines incorporate predictive maintenance algorithms and IoT connectivity to further enhance operational efficiency in both configurations.