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Blister Defects and Remedies in Pharmaceutical.

Blister Film is a plastic processing technology in which a flat plastic sheet is heated softly, vacuum adsorption is applied to the mold surface, and the mold is cooled before being molded. It is extensively used in plastic packaging, lighting, advertising, and decorating. But during the Blister formation, we faced issues related to the quality of blisters and defects. The problems with blister defects and remedies are explained here.

Blister defects and Remedies:

Following are the issues we encounter during the blister packing process:

  1. Leak test failure
  2. Wrinkle on Blister
  3. Cavities Defects
  4. Blister Cavity stuck in forming Plate
  5. Forming station does not open fully
  6. The camera system not working
  7. PRC out of the bend
  8. Pinhole detector not working Probable causes:
  9. Homing not done
  10. Blister Damage in sealing station
  11. Motor overload
  12. Emergency machine stop
  13. Blister dropping problem, machine not stared after press green button
  14. Bend Blister or Twisted blister
  15. Web direction uneven
  16. Dott Impression on PVC/PVDC foil after pocket formation
  17. Web slipping at punching station
  18. Low air Pressure
  19. High-temperature cooling water
  20. Thermocouple check/ perforation blade

1. Leak test Failure:

Probable causes:

  • Improper sealing due to less pressure
  • Sealing temperature less than required
  • ink or extra material deposition on sealing roller

Suggested Action:

  • Maintain sealing pressure up to 5 bar
  • maintain sealing temperature as per BPR
  • Clean the sealing roller with a brash brush

2. Wrinkle on Blister

Probable causes:

  • guide plate alignment with a counter sealing roller is not proper
  • aluminum foil unwinding pressure low
  • the guide roller is not perpendicular to the Front Plate

Suggested Action:

  • align the guide plate properly with the counter sealing roller
  • increase the unwinding pressure to the required level
  • check if the guide roller is not perpendicular and correct it.

3. Cavities Defects

Probable causes:

  • air went partially closed in some area
  • failure of heater
  • height differences between heating and forming station

Suggested Action:

  • check vent, do clean if required
  • check heater properly
  • set heating and forming station height and level.

4. Blister Cavity is stuck in developing Plate.

Probable causes:

  • forming plate not sufficiently cleaned
  • ejection pins are stucks

Suggested Action:

  • check the cooling system, reduce the temperature if required
  • check ejection pin

5. Forming station does not open fully

Probable causes:

  • maybe due to jamming in moving Plate
  • servo motor coupling is loose, or rubber is worn out

Suggested Action:

  • lubricate piller bearing
  • clean if foreign particles deposited in the sliding part
  • replace the rubber

6. The camera system not working

Probable causes:

  • signal or disconnection camera system
  • camera key in special function is not activated

Suggested Action:

  • check the signal coming from a camera
  • activate camera key in special function

7. PRC out of the bend

Probable causes:

  • Eye mark shifted while the machine running
  • distance between two eye marks on foil is not as per drawing

Suggested Action:

  • Teach the PRC scanner
  • check the distance between two eye mark

8. Pinhole detector not working Probable causes:

Probable causes:

  • input in PLC is not connected
  • distance between pinhole and rejection system is not proper

Suggested Action:

  • connect pinhole detector
  • input right distance between pinhole and rejection system

9. Homing not done

Probable causes:

  • homing is not performed

Suggested Action:

  • perform homing of all axis

10. Blister Damage in sealing station

Probable causes:

  • PRC setting not proper
  • improper sealing station knob tightness

Suggested Action:

  • set the PRC
  • Fixed the sealing station

11. Motor overload

Probable causes:

  • motor is overheated

Suggested Action:

  • eliminate the error, wait until the motor has cooled down
  • check the mechanical parts for roughness and blockage
  • clean the drive unit
  • lubricate the moving part

12. Emergency machine stop

Probable causes:

  • an emergency push-button activated

Suggested Action:

  • unlock the emergency knob by turning it.

13. Blister dropping problem, machine not stared after press green button.

Probable causes:

  • splice sensor

Suggested Action:

  • change the number of tracks selected in the PLC after the changeover
  • check the splice sensor, whether it is loose or not
  • do the challenge test for PVC sensor and Alu splice

14. Bend Blister or Twisted blister

Probable causes:

  • guiding roller before the indexing roller

Suggested Action:

  • use the guiding roller having diameter 5mm less than blister width, for example, blister having 110x45mm in which 110mm in length and 45mm in width then, use the guiding roller having a diameter of 40mm. (45mm width-5mm=40mm) to prevent bend blister.

15. Web direction uneven

Probable causes:

  • forming plate

Suggested Action:

  • check the lower forming plate position, tight the lower screw

16. Dott Impression on PVC/PVDC foil after pocket formation

Probable causes:

  • heating plate surface

Suggested Action:

  • use the heating tap on the identified surface from which impression generated

17. Web slipping at punching station

Probable causes:

  • incomplete forming cavities, wrong blister setting in indexing roller
  • improper pickup
  • misalignment of support plate in punching plate

Suggested Action:

  • remove the web from punching and check causes

18. Low air Pressure

Probable causes:

  • no compressed air, leakage in the air pressure line
  • pressure seal defective or set incorrectly
  • faulty setting pressure regulator
  • wire break in cabling in air pressure controller

Suggested Action:

  • activate the compressed air supply, check pressure gauge or maintenance unit

19. High-temperature cooling water

Probable causes:

  • thermocouple for cooling water is not connected

Suggested Action:

  • connect the thermocouple, replace the defective one

20. Thermocouple check/ perforation blade

Probable causes:

  • actual pressure of thermocouple blade is below 50°C

Suggested Action:

  • check thermocouple connection
  • replace the defective thermocouple
  • set the perforation blade temperature above 50°C

Conclusion:

The quality of the blister depends on the material and machine setting as per the given parameters. But sometimes, small problems can lead to harm the quality of products. I hope topics related to blister defects and remedies will cover all these minor or major problems.

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