Troubleshooting guide for Tubular Quenched PP Blown Film Applications
Tubular Quenched PP Blown Film Troubleshooting
Problem
Probable Cause
Suggested Remedy
Temperature Setting
Temperature setting are crucial parameter for proper plastic processing ,hence one should check temperature controller, thermocouple and solid state relay(SSR)
- when you cold start the machine ,wait for 2hours.
Poor operability of film
- Too much temperature of barrel and die
- Too low temperature of cooling water
- Too large quantity of cooling water
- Insufficient air flow at air ring
- Too much pressure at nip rolls
- Higher drying temperature
- Moisture in raw material
- Reduce temperature of barrel and die but not too low for operability
- Increase water flow rate or increase cooling water temperature
- Decrease water flow rate
- Increase air blower damper to the extent that film does not shiver
- Loosen nip rolls carefully such that no air should enter in the film bubble
- Reduce drying temperature below 50°C
- Dry resin preferably > 50°C
Poor Clarity
- High temperature of cooling water,Inadequate flow of cooling water
- Excessive air cooling
- Low temperature of barrel and die
- Lower water temperature, increase water flow rate
- Reduce quantity of air gradually by closing damper of air blower
- Raise temperature of barrel and die
Partial white patches
- Incorrect contact with sizing ring
- Partial water repellency created at sizing ring due to contamination by polymer fines, dust, oil, or grease
- Inadequate air in the film bubble
- Film thickness is not uniform, film tube is preliminarily cooled by air ring
- Tiny scratch owing to friction against guide plate
- Check and adjust the centering between die and nip rolls, adjust and centering of sizing ring, check uniformity of water flow around sizing ring
- Clean sizing ring with detergent
- Restore contact of bubble with sizing ring, blow air gradually through die nozzle and inflate tube, establish contact of film with sizing ring perfectly
- Adjust die lip clearance carefully with adjusting bolt to get uniform thickness of film
- Increase flow rate of cooling water enough to make film tube run smoothly inside sizing ring along guide plate, increase line speed
Appearance of stripes
- Higher blow-up ratio
- Insufficient quantity of water
- Sizing ring and guide plate are rusty, scratched
- Decrease quantity of air in the tube
- Increase water flow rate, create uniform water membrane between sizing ring and guide plate by adjusting water flow rate
- Polish and clean sizing ring and guide plate with sand paper
Poor gloss of film
- Reduce temperature of die and barrel
- High water temperature
- Excessive cooling air
- Water squeezing and film drying are not satisfactory
- Increase temperature of barrel and die
- Drop water temperature of barrel and die
- Reduce air flow rate
- Raise film drying temperature
Non-uniform gauge of film
Die lip opening incorrect, non-uniform flow of cooling water around the tube
Adjust the mandrel within the die, adjust uniform cooling water flow around the tube, adjust die bolt for uniform gauge of film
Improving mechanical properties of the film
The most important parameters which affect physical properties of film are: extruder output, blow-up ratio, cooling water flow rate and temperature, take-off speed
Optimisation of these process variables
