There are a wide variety of issues that can occur when shrink wrapping products using shrink film. We are going to help you understand the common problems and solutions along with the terminology used for describing shrink wrapping issues. Most of these issues are pretty common and easy to resolve by adjusting machine settings. Typical solutions to resolve shrink wrapping issues are adjusting temperature, air velocity, and conveyor speed of the shrink tunnel. The size and quantity of perforations also have a significant effect on how fast the balloon forms and how fast it collapses as the film shrinks. The rate at which air escapes the film must be analyzed in order to get the best looking package.  Before you start, make an empty bag on your sealer with air inside and squeeze it to see if the air is escaping and where. Then pull on each seal individually to make sure they are strong. If your seals are not strong you will never get a good shrink. Seal strength is dependent on time, temperature and pressure. It is also critical that the film be relaxed and not under ANY stress when you seal or you will get weak seals.

Dog Ear

A dog ear is the most common issue in the shrink wrapping world and it is often seen on many of the shrink wrapped products in a retail store. Dog ears are triangular protrusions of the shrink film at the corners of the product which indicate lack of shrinkage. They often occur on corners, or in areas where large amounts of excess film are located BEFORE shrinking is completed.

Causes:

1. Improper amount of heat
2. Shrink film bag too large
3. High or round product with too many perforations in the wrong place
4. Too many perforations or weak seals that allow air to escape too quickly

Solutions: Do one at a time!

1. Increase or decrease the tunnel temperature in increments of 10 degrees and monitor package shrink.
2. Reduce the bag size of the package before shrinking. (Make a tighter bag)
3. Increase or decrease perforations or add hole punch.
4. Lower the tunnel conveyor speed.
5. Increase the tunnel air velocity.
6. Correct amount of perforation.

Fish Eyes

Fish eyes are round or oval patterns on a package caused by poor shrinking. Fish eye’s makes your package look very unprofessional.

Causes:

1. Insufficient heat.
2. Improper air velocity.
3. To many perforations or bad seals.

Solutions:

1. Heat up the tunnel temperature to proper amount of heat.
2. Provide enough tunnel air velocity from your heat source.
3. Lower the tunnel conveyor speed
4. Reduce the bag size.

Crow’s Feet

Crow’s feet are wrinkles emerging from the corners of shrink wrap package. They are almost always accompanied by Dog’s ears

Causes:

1. Excessive film on corners of the product
2. Insufficient heat

Solutions:

1. Try using thinner centerfold shrink film
2. Reduce the air evacuation from shrink film containment
3. Reduce or lower the amount or size of air holes
4. Reduce the bag size

Angel Hair

Angel hairs are thin strands of shrink film between the product being sealed and the sealed end of the shrink wrap film. A large angel hair on the package is not attractive.

Causes:

1. Low sealing temperature
2. Uneven clamp pressure
3. Incomplete sealing
4. Type of shrink film
5. Type of seal blade, wire or knife being used

Solutions:

1. Increase the sealing temperature to proper amount
2. Apply even clamp pressure
3. Use compatible shrink film

Ballooning

Ballooning happens when the shrink film is exposed to hot air. The air inside sealed film expands and causes it to gust out making it look like a balloon.

Causes:

1. No perforation for air evacuation on the film
2. Improper positioning of perforated holes

Solutions:

1. Apply proper perforation to the film
2. Do not let excessive air enter the film before shrinking
3. Position the holes properly for air evacuation
4. Add more air holes

Burn Out

Burn outs are usually caused by excessive heat applied on the shrink film, which leads to burning or tearing while shrinking. It causes unwanted holes on shrink film. Burn out symbolizes improper heat on the bubble of the package. It can be detected during trials and corrected before final shrinking of package. Look inside the tunnel as the product is shrinking to see what is happening.

Cause:

1. Not enough perforation
2. High temperature
3. Tunnel conveyor too slow
4. Voids in package

Solutions:

1. Apply enough holes for air evacuation
2. Reduce tunnel temperature
3. Increase tunnel conveyor speed
4. Use thicker gauge shrink film

Hazing

Hazing is when the shrink film starts to get “cloudy” after the shrinking process. It typically happens around voids, especially when wrapping rounded bottles.

Cause:

1. Excessive heat causing film to burn

Solutions:

1. Reduce the tunnel temperature in increments of 10 degrees and monitor package shrink
2. Increase the speed of the conveyor

 

That sums up the most common shrink wrapping issues and their solutions. Make sure you have a perfect package before sending it out to your customers. Feel free to Contact Us at (416) 299-0960 if you are unable to resolve any issues and one of our Impak representatives would be happy to assist you.