GZbohangzhineng@163.com
+86-18675873677
Maintaining stable air pressure is one of the most critical aspects of ensuring consistent bottle quality in a PET bottle blowing line. When pressure fluctuates or drops, it can lead to poor bottle formation, deformation, or production stoppages. Understanding how to identify, analyze, and resolve these air pressure issues will help maintain continuous and efficient operation. For factories using high-efficiency blow Molding systems such as those provided by BOHANG, stable air pressure management ensures maximum machine output and reduces production downtime.
In a PET bottle blowing system, compressed air is responsible for shaping preforms into finished bottles by forcing the heated plastic against the mold walls. This process typically involves high-pressure air ranging from 25 to 40 bar. If the pressure is unstable, the preform may not expand evenly, leading to thin walls, dents, or partial deformation. Maintaining consistent air pressure throughout the blowing cycle is essential to achieving accurate bottle shapes, uniform thickness, and smooth surface finishes.
When pressure irregularities occur, certain production indicators can help operators identify the issue early:
Incomplete bottle shape: The bottle appears partially formed, indicating insufficient blowing pressure.
Uneven wall thickness: Pressure loss during the stretching phase causes inconsistent plastic distribution.
Slower cycle time: The blower compensates for pressure loss, reducing efficiency.
High reject rate: Fluctuating pressure leads to more defective bottles.
Air compressor alarms: Frequent triggers indicate leakage or capacity mismatch.
Recognizing these signs allows maintenance teams to pinpoint the issue before it affects product consistency or causes system failure.
The air compressor is the heart of the bottle blowing system. If the compressor’s output is below specification, the entire line suffers. Begin by verifying:
Pressure gauge readings at the compressor outlet. The output should remain within the specified range under load.
Compressor load and unload cycles. Excessive cycling may indicate air leakage or undersized capacity.
Air filter condition. Clogged filters restrict airflow, lowering pressure.
Compressor oil level and temperature. Overheating or low oil can reduce efficiency and air volume.
If the compressor cannot sustain consistent pressure, consider increasing air storage capacity or scheduling routine maintenance to prevent performance degradation.
Even if the compressor functions correctly, leaks or restrictions in the air distribution network can cause pressure drops before reaching the blower. Inspect:
Air receivers and tanks for cracks, rust, or improper drainage that reduce effective volume.
Piping joints and valves for leaks using a soapy water test or ultrasonic detector.
Pressure regulators and gauges for calibration accuracy.
Pipe diameter. Undersized piping increases pressure loss over distance.
A well-designed system should have minimal pressure difference between the compressor and the blow molding machine inlet. If the measured loss exceeds 5%, the distribution network likely requires optimization.
Moisture and impurities in the compressed air line can also affect bottle quality and cause uneven pressure delivery. Key inspection points include:
Refrigeration or desiccant dryers. Check dew point levels to ensure dry air is supplied.
Primary and secondary filters. Replace clogged filters regularly to avoid pressure restrictions.
Drain valves. Automatic drains should function correctly to prevent moisture accumulation in air lines.
Maintaining clean, dry air reduces not only pressure issues but also prolongs the lifespan of valves and cylinders in the blowing unit.
Inside the Bottle Blowing Machine, valves control the timing and intensity of air delivery during the pre-blow and main blow stages. Malfunctioning valves or sensors can cause inconsistent bottle formation. Technicians should:
Test solenoid valve response times using diagnostic software or manual activation.
Inspect seals and diaphragms for wear or air leakage.
Check pressure sensors for calibration drift or contamination.
Monitor blow cycle data from the machine control system to identify irregular patterns.
Replacing worn components promptly ensures stable air pressure control during every cycle.
Environmental factors also affect air system performance. High ambient temperatures or humidity can reduce compressor efficiency. Ensure the compressor room is well-ventilated, with stable operating conditions between 20°C and 35°C. Additionally, analyze production load variations. When multiple blowers or molding lines share a common air supply, sudden demand peaks can drop pressure temporarily. Installing a pressure regulator or booster system near the blowing station can help maintain stability.
To prevent future pressure issues, adopt a scheduled maintenance plan that includes:
| Inspection Item | Frequency | Key Actions |
|---|---|---|
| Compressor oil & filter | Weekly | Check oil level, replace filters |
| Air receiver drainage | Daily | Drain moisture and condensate |
| Air filter cleaning | Weekly | Replace or clean elements |
| Pressure sensor calibration | Monthly | Verify against reference gauge |
| Valve seal inspection | Quarterly | Replace worn seals or gaskets |
A consistent maintenance schedule reduces unexpected downtime and ensures every blow molding batch maintains uniform quality.
A stable and reliable air system depends not only on maintenance but also on machine design. Advanced PET bottle blowers from BOHANG integrate precision valve control systems, energy-efficient compressors, and modular air circuits designed for long-term stability. Their machines are engineered to maintain consistent high-pressure air delivery, reducing fluctuation even under high production loads. Choosing equipment with optimized pneumatic systems ensures better energy efficiency, fewer rejects, and smoother production flow.
Air pressure issues in bottle blowers can significantly disrupt production efficiency and product quality. By methodically checking each part of the air system—from the compressor and dryer to the valves and control sensors—operators can quickly identify and correct the root cause. Implementing preventive maintenance and using well-engineered systems such as those from BOHANG ensures that your PET bottle production remains stable, efficient, and cost-effective over time.
