PET Blow Moulding

PET (Polyethylene Terephthalate) Blow Moulding, specifically, **stretch blow moulding**, is the dominant bottle-forming process for water, juice, CSD, and edible-oil packaging. The process: 1. **Preform**, a small, test-tube-shaped PET injection-moulded part is fed into the machine. 2. **Heating**, preforms are heated to 95–115°C in a zoned IR oven for 12–25 seconds. 3. **Stretching**, a stretch rod axially elongates the preform inside the mould. 4. **Blowing**, high-pressure air (28–35 bar) expands the preform radially against the mould walls. 5. **Cooling & ejection**, the bottle cools against the mould (typically chilled at 8–12°C) and is ejected. Machine architectures: - **Linear:** preforms move in a straight line. Cost-effective up to 8,000 BPH. - **Rotary:** continuous wheel motion. Required above 8,000 BPH. Cavity count = bottles per cycle. A 4-cavity linear at 18 cycles/minute = 72 BPM = 4,320 BPH.