Common Issue in Blown Film Machines: Excessive Die Lip Buildup

Description

Die lip buildup is a frequent issue in blown film production, where residues accumulate at the die exit (die lip). This buildup causes uneven film thickness, surface defects, and even film breaks or winding irregularities, significantly impacting product quality.

Analysis

1.Material Contamination or Degradation

Impurities or volatile components in raw materials carbonize and adhere to the die lip.

Excessive processing temperatures cause polymer degradation.

2.Improper Process Parameters

Fluctuations in melt temperature or pressure lead to unstable extrusion.

Insufficient cooling from the air ring prolongs melt contact with the die lip.

3.Inadequate Maintenance

Infrequent die cleaning allows residues to harden over time.

Procedures

1. Immediate Cleaning

Use copper scrapers or non-abrasive tools (e.g., brass brushes) for soft buildup.

Recommended cleaners: Silicone-based or fluorocarbon solvents; avoid chlorine-based chemicals.

2. Deep Cleaning

For severe buildup, disassemble the die and use ultrasonic cleaning or high-temperature salt baths.

Inspect die lip flatness before reassembly.

3. Process Optimization

Adjust extrusion temperature (reduce by 5~10°C) to minimize degradation.

Optimize air ring airflow to accelerate melt solidification.

4. Preventive Maintenance

Clean the die lip every 8 hours of operation.

Purge the screw and die when switching materials.

Reminders

Wear heat-resistant gloves during cleaning.

Die disassembly should be performed by trained personnel to prevent seal damage.

Regular maintenance and process control are essential to prevent die lip buildup. Selecting the right cleaning method for your materials can significantly improve productivity and film quality.