Technical Issue

Shrink Films Problems and Solutions

During the shrink packaging process, some problems may occur like ballooning, burn out, fish eyes etc... Actually all these problems can be easily fixed by changing the setting of machineries. Most commonly setting are the tunnel temperature, tunnel air velocity, tunnel conveyor, number of perforation and film bag size.

Some common shrink problems and solutions will illustrate below:


Ballooning

Hot air retain inside the shrink bag.
Solutions:

  1. No or not enough air evacuation holes in the shrink films bag. Increase the number of air evacuation holes.
  2. Shrink tunnel conveyor speed set too fast. Lower the shrink tunnel speed.
  3. Shrink tunnel temperature set too low. Increase the shrink tunnel temperature.

 

Burn Out

 A cloudy appearance or burns through of the shrink film after passing though the shrink tunnel. 
 Solutions:

  1. No or not enough air evacuation holes in the shrink films bag. Increase the number of air evacuation holes.
  2. Shrink tunnel temperature set too high. Lower the shrink tunnel temperature.
  3. Shrink tunnel conveyor speed set too slow. Speed up the shrink tunnel conveyor speed.

 

 

Weak Seal

The sealing line of the shrink bag is easy to broken or has some small holes on it.
Solutions:

  1. The temperature of the sealing blade is too high. Lower the sealing blade temperature.
  2. Sealing line position is not suitable. Sealing line should be at the middle of the product.
  3. Seal pressure apply on the film is not even. Modify the sealing blade and make it even. Check the seal pad to see whether the pad is damage or not. If yes, replace the seal pad.
  4. Sealing surface of the sealing blade or sealing base dirty. Cleaning the surface of the sealing blade and sealing base.
  5. Damage of the seal pad or seal tape. Replace the seal pad or seal tape which is damage.
  6. The sealing cycle is too fast, not enough time to complete sealing. Slow down the sealing cycle.

 

 


Fish Eyes

Scalloped surfaces occur on the shrink-film package.
Solutions:

  1. Shrink tunnel temperature is too low. Increase the shrink tunnel temperature.
  2. Shrink tunnel blower speed is too low. Increase the shrink tunnel blower speed.
  3. Conveyor of the shrink tunnel is too fast. Slower down the conveyor speed.

 

  • Crows Feet

Series of wrinkles radiating out from the corner of an over wrapped package.
Solutions:

  • Shrink tunnel temperature is too low. Increase the shrink tunnel temperature.
  • Shrink tunnel blower speed is too low. Increase the shrink tunnel blower speed.
  1. Too many air evacuation holes in the shrink films bag. Decrease the number of air evacuation holes.
  2. Shrink tunnel conveyor speed too fast. Slow down the conveyor speed.

 

 

Dog Ear

Triangular projections of shrink film at the corners of the bag.
Solutions:

  1. Shrink film bag is too large. Make the shrink film bag smaller.
  2. Shrink tunnel blower speed is too low. Increase the blower speed.
  3. Shrink tunnel temperature is too low. Increase the shrink tunnel temperature.
  4. Shrink tunnel conveyor speed too fast. Slow down the conveyor speed.

 


Angel Hair

Some very thin stands of film appearing between the cut end of the film and the packaged item.
Solutions:

  1. The sealing blade temperature is too low. Increase the sealing blade temperature.
  2. The sealing system is not compatible to shrink films.

 

Bad Seal Position

The sealing line of the shrink film bag is not on the center of the product.
Solutions:

  1. The height of sealing table or conveyor belt on the machine is improper. Try to reset the height of the sealing table or conveyor belt.
  2. Height of the sealing frame is improper. Reset the sealing frame height.
  3. The blower direction of the shrink tunnel set wrong. Reset the blower direction of the shrink tunnel.
  4. Shrink film bag is too large. Make the shrink film bag smaller.

 

 


Crushing

The product is crushed by the shrink film because the shrinking force is too large.
Solutions:

  1. Shrink tunnel temperature is too height. Decrease the shrink tunnel temperature.
  2. Shrink tunnel conveyor speed is too low. Increase the shrink tunnel conveyor speed.
  3. Shrink film bag is too small. Make the shrink film bag bigger.
  4. Shrink film is not compatible to pack the product. Select the other shrink film.

 

Zippering

Shrink film surface have a tearing appearance.
Solutions:

  1. Pin perforate system tearing the firm. Check the pin perforator to see whether the pressure of the pin roller is too height.
  2. Air evacuation holes are not enough. Increase the number of the air evacuation holes.
  3. Sharp edges in film path.