Incomplete PET Bottle Blowing: Soft Panels and Unformed Feet

Check whether the pressure curve reaches and holds the target, then inspect leaks, valve timing, preform heat, mould venting, stretch motion and high-pressure air capacity. Do not compensate for a leak by raising pressure.

Isolate high-pressure air, electrical power, heating circuits and motion energy before entering the guarded area. Treat hot oven components and pressurized blowing circuits as stored-energy hazards.

Locate the fault

• Bottle details and feet are not fully formed
• Panels feel soft and dimensions are undersize
• The fault worsens when several cavities blow together
• Micro-hole detection or pressure control rejects bottles

Inspection sequence

1. Compare actual pressure curves by cavity under the same recipe
2. Check supply pressure and recovery during simultaneous blowing
3. Perform approved leak tests on neck seal, valve and circuit
4. Measure preform temperature profile at oven exit
5. Inspect stretch timing and rod travel
6. Clean and inspect mould vents after full isolation

Corrective work

• Restore high-pressure supply capacity and validated timing
• Replace leaking seals, valves or connections
• Correct the heating profile and stable oven condition
• Clean damaged or blocked vents without altering mould geometry

Operating records and follow-up

• Trend cavity pressure curves
• Maintain high-pressure filters and dryers
• Replace neck seals by condition
• Clean vents on a defined schedule
• Verify pressure recovery at maximum production demand

Equipment details: PET Bottle Blow Molding Machine.