PET Blow Moulding in the Bottling Industry
PET blow moulding machines convert preforms into finished containers through a precisely controlled stretch-blow process. On the used market, machines from manufacturers such as Sidel, KHS, SIPA, SIAPI, SMI, and Tech-Long represent significant investment opportunities when properly evaluated.
Linear vs Rotary Blow Moulders
| Feature | Linear | Rotary |
|---|---|---|
| Speed | Up to 10,000 BPH | Up to 80,000+ BPH |
| Cavity count | 1–6 cavities | 6–36+ cavities |
| Footprint | Compact | Larger |
| Format change | Faster | More complex |
| Investment | Lower | Higher |
| Best for | Small-medium production | High-speed continuous |
Oven Section Evaluation
The oven (heating) section is critical for consistent bottle quality. Inspect infrared lamp condition, reflector degradation, preform rotation spindles, and ventilation system efficiency. Worn lamps produce uneven heat distribution causing wall thickness variation.
Mould Condition Assessment
- Parting line wear causing flash on bottles
- Cooling channel blockage reducing cycle time
- Base plug condition affecting bottle stability
- Stretch rod alignment and wear
- Locking mechanism condition
Energy Consumption Considerations
Blow moulders are among the highest energy consumers in a bottling line. Older machines may consume 30–50% more energy per bottle than current models. Evaluate compressed air consumption (40 bar high-pressure air is expensive), oven energy efficiency, and cooling water requirements.
Common Mistakes
Mistakes to Avoid
- Ignoring oven lamp replacement costs — a full lamp set can cost €5,000–€15,000
- Not checking high-pressure compressor compatibility — blow moulders require 35–40 bar air
- Overlooking mould cooling circuit blockage — reduces output and bottle quality
- Buying without verifying preform neck finish compatibility with your closure system
- Assuming all PET blow moulders can handle heat-set applications — most cannot
Frequently asked questions
What is the difference between single-stage and two-stage blow moulding?
Single-stage machines produce preforms and blow bottles in one integrated process. Two-stage machines use separately manufactured preforms, offering greater flexibility and typically higher speeds.
How long do blow moulds last?
Well-maintained moulds typically last 3–5 million cycles. Mould refurbishment can extend life by 50–70% at a fraction of new mould cost.
Can I change bottle designs on a used blow moulder?
Yes, by purchasing new moulds for your desired bottle shape. Verify the machine accepts the mould size and type before ordering.