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The cleaning frequency depends on production volume and raw materials.
Generally, manufacturers should clean the die head:
During material changes
After carbon buildup
When black spots appear
During routine maintenance
Proper cleaning improves film quality and extends die head service life.
| Unstable die head temperature | Check the heater function is normal |
| Check the thermocouple position is correct | |
| Die head throughput fluctuations | Adjust the die gap |
| Regular cleaning of die head, screw and hilter | |
| Non-uniform cooling air volume | Check air ring for dirt buildup or breakage |
| Adjust air ring position | |
| Check whether air pipe is damaged | |
| The air flow in the factory is too fast | Do not let outdoor air directly enter the factory |
| Extruder throughput instability | Cool down the hopper throat to avoid plastic blocking |
| Replace the strainer meshes of Filter to avoid blocking | |
| Matter of the formula |
| Blow-up ratio | Use a smaller die head to increase the blow-up ratio |
| Improper die design or scratches | Clear die impurities |
| Fix scratches on the die head | |
| Avoid seams by design | |
| Material cracking | Change the material |
| Turn down heating temperature | |
| Inappropriate raw material formula | Select raw materials with suitable Melt Index (MI) |
| Select compatible additives | |
| Uneven gels mix | Use screw with a greater L/D |
| Adjust the melt temperature | |
| Use multi-layer strainer meshes for filter, or reduce the die gap, to improve back pressure |
| Inappropriate ink | Choose the right ink |
| Improper use of additives | Reduce the amount of additives |
| Use the appropriate surface lubricant | |
| Insufficient corona treatment | Increase the treatment voltage or wattage |
| Reduce the take-up speed | |
| Narrow the gap of the electrode | |
| Raise the electrode treatment temperature | |
| Air humidity too high | Reduce the air humidity |
Blown film die heads are commonly used for:
HDPE
LDPE
LLDPE
MHDPE
PP
Multilayer co-extrusion materials
Different die head designs are optimized for different resin flow characteristics and film applications.
HDPE die heads are designed for high-pressure blown film production and are commonly used for shopping bags and grocery bags.
LDPE die heads are suitable for low-pressure blown film applications and are widely used in food packaging, agricultural films, and flexible packaging.
The flow channel design, air volume requirement, and cooling configuration are different between HDPE and LDPE systems.
An air ring delivers uniform airflow around the molten film bubble to cool and stabilize the film during extrusion.
The air ring directly affects:
Film thickness consistency
Bubble stability
Cooling efficiency
Optical film quality
Production speed
Single lip air rings provide basic cooling performance and are suitable for standard film production.
Dual lip air rings provide more stable airflow distribution and better cooling efficiency, making them ideal for high-speed and high-quality blown film production.
Uneven film thickness may be caused by:
Improper die head adjustment
Unstable air ring airflow
Incorrect temperature settings
Poor raw material quality
Bubble instability
Damaged die lips
Regular maintenance and precision die head design help improve thickness uniformity.
A screen changer filters contaminants and impurities from molten plastic before extrusion.
Benefits include:
Better film quality
Reduced black spots
Improved die protection
More stable extrusion pressure
Longer equipment life
ARE YOU STILL NOT SURE WHICH TYPE OF DIE HEAD YOU WANT TO BUY?
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