Common Issues and Solutions in the Film Blowing Process 

The Blown Film Machine is essential for producing plastic films by extruding molten polymer and inflating it into a thin, continuous tube. However, various challenges can arise during the process, impacting film quality, consistency, and efficiency. Common problems include poor film adhesion, uneven thickness, surface defects, and more. Addressing these issues effectively is key to optimizing production and maintaining high-quality output. Below, we explore frequent film-blowing problems and their solutions.  

Poor Film Opening (Film Too Sticky)  
 

Causes:

Incorrect resin type (not designed for blown film) or insufficient opening agent.  
Excessive melt temperature, increasing resin fluidity.  
Excessive blow-up ratio.  
Slow cooling, causing film layers to stick.  
Excessive traction speed.  

Solutions: 

Use the correct resin grade or add an opening agent.  
Lower extrusion and resin temperatures.  
Reduce the blow-up ratio.  
Increase cooling airflow for faster film solidification.  
Decrease traction speed.  

Low Film Transparency
 

Causes:

Low extrusion temperature, leading to poor resin plasticization.  
Insufficient blow-up ratio.  
Inadequate cooling.  
High moisture content in resin.  
Excessive traction speed, reducing cooling time.  
 

Solutions:  

Increase extrusion temperature for better plasticization.  
Raise the blow-up ratio.  
Enhance cooling efficiency with higher airflow.  
Pre-dry resin to reduce moisture.  
Reduce traction speed for proper cooling.  

Film Wrinkling
 
Causes: 

Uneven film thickness.  
Insufficient cooling.  
Excessive blow-up ratio, causing bubble instability.  
Excessive herringbone splint angle.  
Uneven pressure on traction rollers.  
Misaligned guide rollers.  
 

Solutions:

Adjust die gap for uniform thickness.  
Improve cooling to ensure full solidification.  
Reduce blow-up ratio for stability.  
Decrease herringbone splint angle.  
Balance traction roller pressure.  
Align guide rollers properly.  

Mist-Like Water Marks on Film
 

Causes:

Low extrusion temperature, leading to poor plasticization.  
High moisture content in resin.  
 

Solutions: 

Increase extrusion temperature.  
Dry resin to maintain moisture below 0.3%.  

Uneven Film Thickness
 

Causes: 

Non-uniform die gap.  
Uneven die temperature distribution.  
Inconsistent cooling airflow.  
Improper blow-up or traction ratio.  
Fluctuating traction speed.  

Solutions: 

Adjust die gap for consistency.  
Ensure uniform die temperature.  
Balance cooling airflow.  
Optimize blow-up and traction ratios.  
Stabilize traction speed.  

Excessive Film Thickness

Causes:

Oversized die gap or excessive extrusion volume.  
Excessive cooling airflow, causing rapid solidification.  
Slow traction speed.  

Solutions: 

Adjust die gap.  
Reduce cooling airflow to allow further inflation.  
Increase traction speed.  

Insufficient Film Thickness

Causes:

Too small die gap, increasing resistance.  
Insufficient cooling airflow.  
Excessive traction speed, overstretching the film.  

Solutions: 

Widen die gap.  
Increase cooling airflow.  
Reduce traction speed.  

Poor Heat Sealability
 

Causes:

Low dew point, increasing molecular orientation.  
Excessive blow-up or traction ratio.
 

Solutions:

Adjust cooling to raise dew point.  
Reduce blow-up and traction ratios to minimize orientation.  

Conclusion  

The Blown Film Machine is highly efficient but requires precise control to avoid defects. By understanding common issues—such as poor film opening, uneven thickness, or heat seal problems—and implementing corrective measures, manufacturers can enhance film quality and production efficiency. Proper material selection, machine calibration, and process monitoring are essential for minimizing defects and ensuring smooth operations. Addressing these challenges proactively improves both machine longevity and overall production economics.  
 

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