A variety of issues can arise when shrinking wrapping products with shrink film.

We will cover common problems and solutions when wrapping with shrink wrap machines.

Most of these issues are familiar and easy to resolve by adjusting machine settings.

Among them are often adjustments of shrink tunnel temperature, circulating air speed, conveyor belt speed, number of vent holes, and changing shrink film.

Ⅰ. Shrink Film Ballooning

Excess air trapped inside the sealed shrink film.

The reason is that shrink film is exposed to hot air after sealing.

Shrink Film Ballooning

Solution:

1. You can buy pre-punched heat shrink film. There are many small needle-sized vent holes in this type of film.

Or add the number of vent holes to the film you have already purchased.  Increase air escape velocity when shrink film wraps product.

At KEEPTOP Packaging We sell pre-perforated shrink film rolls and bags to prevent.

2. Slow down conveyor speed of shrink wrap machine and shrink tunnel.

Helps hot air have more time to escape from shrink wrap.

3. Raise the temperature of the shrink tunnel to increase the speed at which the air is expelled from the heat shrink wrap.

Ⅱ. Burn Holes on shrink films

A cloudy appearance or burn Holes through the heat shrink film after passing through the heat shrink tunnel.

The reason is that too much heat is applied to the shrink film.

Burn Holes on shrink films

Solution:

1. Reduce the temperature of the shrink tunnel machine.

2. Increase the conveyor speed of shrink wrap machines and shrink tunnels.

3. Increase the number of vent holes in shrink wrap rolls.

Ⅲ. Dog Ears On Shrink Wrap

Shrink film is bunched up in the corners of the package. They resemble a dog ear.

It is a widespread problem when shrink wrapping.

Dog Ears On Shrink Wrap

Solution:

1. Utilizing a larger film width than necessary can result in dog ears appearing on the corners of your finished goods.

Packaging products with less shrink film roll to reduce the width of the film.

2. If the temperature of the heat tunnel is too low, Increase the temperature.

3. The heat tunnel blower speed is too low. Increase the blower speed.

4. If using PVC shrink film, switch to POF shrink film. PVC is more brittle after heated.

5. If the product is irregularly shaped, it can also cause dog ears after heating.

Ⅳ. Fish Eyes on shrinkable film

There are circular or oval patterns on the surface of shrink wrap film, and the shrinking effect is poor.

The reason is lack of heat.

This is also a common problem in shrink wrapping. When solving for dog ears, you will often solve for crow feet too.

Fish Eyes on shrinkable film

Solution:

1. Increase the temperature of the heat shrink tunnel.

2. Reduce the speed of shrink wrapping machine and heat tunnel conveyor belt. Increase heating time.

3. If the air speed of the heat shrink tunnel blower is too low, increase the airspeed.

The wrap doesn’t shrink consistently if your heat source is not pushing enough air when applying heat.

Ⅴ. Crow’s Feet on heat shrinkable film

Crow’s feet are wrinkles extending from the corners of your packages.

Crow Feet on heat shrinkable film

Solution:

1. Using a smaller heat shrink wrap roll. Excessive film on the corners of the product occurs if there is too much film wrapping the product.

2. Temperature of shrink tunnel machine is too low Increase temperature.

3. Decrease the speed of the conveyor belt to allow enough time for the shrink film to heat.

4. Increase the air speed of the heat shrink tunnel blower.

5. There are too many vent holes on the shrink film, reduce the number or replace the film.

The hot air can fully heat the shrink wrap film and help it to shrink consistently.

Ⅵ. Weak sealing line on heat shrink wraps

The reason is that the seal bar sealing effect is not good.

Weak sealing line on heat shrink wraps

Solution:

1. Reduce the temperature of the shrink wrapping machine’s hot knife.

2. The height of the sealing line should be in the middle of the package height.

3. The seal bar pressure applied to the film is not uniform. Adjust the seal bar to be level. Replace the gasket if it is damaged.

4. Clean the surface of the hot knife and seal base.

5. Replace the thermal pad if it is damaged.

6. The hot knife sealing time is too short. There is not enough time to complete the sealing. Extend sealing time.

Ⅶ. The sealing line is not in the center of the package height

not in the center

Solution:

1. The height of the sealing table or conveyor belt on the shrink wrappers is incorrect. Adjust the height of the sealing table or conveyor belt.

2. The direction of the shrink tunnel blower is incorrect. Adjust the direction of the blower.

3. Packaging products with less shrink film roll to reduce the width of the film.

Ⅷ. Angel Hair On heat shrinkable film

There are very thin strands of melted plastic between the product and the film.

The reason is the seal bar not being hot enough.

angel hair on shrinkable film

Solution:

1. Increase the temperature of the hot knife of the seal bar.

2. The seal bar pressure applied to the film is not uniform. Adjust the seal bar to be level.

Ⅸ. Deformed or crushed product

The shrinking force is too large, and the product is crushed by the heat shrink film.

Deformed or Crushed Product

Solution:

1. The temperature of the shrink tunnel is too high, decrease the heat.

2. The speed of the shrink tunnel conveyor belt is too slow. Increase the speed.

3. The size of the shrink film is too small, use a large shrink film.

Ⅹ. Zippering

There are zipper-like, intermittent holes on the surface of the shrink film.

Zippering

Solution:

1. The pinwheel perforating device tears the shrink film. Check if the pinwheel perforating device pressure is too high.

2. Increase the number of vent holes.

High-quality heat shrink film plays a crucial role in heat shrink wrapping, as evidenced by the cases discussed.

Taking Polyolefin Shrink Film as an example, what are the standards that define a high-quality POF shrink film?

To learn more about this, please refer to the POF Shrink Film Testing Standards and Compliance.

The Importance of Regular Maintenance of Shrink Wrappers

The above article shows that you need to understand the equipment‘s structure fully. Know which parts to adjust when problems are found during the packaging process.

And proper regular maintenance of your packaging line can greatly reduce the number of damaged goods you see.

The following takes the automatic L sealer as an example of regularly maintaining the machine.

automatic L bar sealer demo

1. Clean the conveyor belt

Air Blowing Nozzle clean the conveyor belt

The operator must clean the belt with the Air Blowing Nozzle before working.

2. Maintenance of air pressure regulating valve

When the height of the water level in the filter reaches 2/3, the operator should drain the water.

Maintenance of air pressure regulating valve

Operation method:

  • Close the intake valve.
  • Exhaust the air inside.
  • Press the drain switch at the bottom of the filter to drain the water.

3. Hot knife maintenance

Hot knife maintenance

Clean the hot knife with a soft cotton cloth each time the machine stops.

Note: Please clean the hot knife before the temperature has dropped. If the temperature is below 70 degrees Celsius (158 degrees Fahrenheit), it may damage the Teflon.

4. seal bar screw

1. Maintenance once a month

2. If the screw of the seal bar is loose, tighten the screw.

5. Check Teflon on the hot knife

If the Teflon on the hot knife comes off, it will cause the shrink films to stick to the hot knife easily.

The hot knife needs to be reprocessed with Teflon or replaced with a new knife.

Check Teflon on the hot knife

6. Replacing the electric heating tube

When the electric heating tube is damaged, it cannot heat the knife.

Need to replace the new electric heating tube.

Note that the voltage and power of the new electric heating tube must be matched before replacing the old one.

Replacing the electric heating tube

Operation steps:

  • Turn off the power and wait for the electric heating tube to cool down.
  • Disconnect the electric heating tube wires in the wiring box.
  • Loosen the screw of the electric heating tube, take it out, and install a new one.
  • Tighten the screws, connect the electric heating tube wiring and lock the wiring box.

7. Waste File Recycling Wheel Maintenance

Waste File Recycling Wheel Maintenance

1. Maintenance once a month

2. Remove the recovery wheel nut, take out the spring, and recovery wheel

3. Apply butter on the contact surface between the shaft and the recovery wheel to ensure smooth operation.

4. Put the recovery wheel and spring back, and tighten the nut

8. chain maintenance

apply butter to the chain

1. Maintenance every three months.

2. Remove the chain protection cover, apply butter to the chain, and then reinstall the cover.

9. Bearing and Bearing housing maintenance

Bearing and Bearing housing maintenance

1. Maintenance once every three months.

2. Drop the hydraulic oil in the contact gap between the bearing and the shaft to maintain lubrication.

10. Check conveyor belt tightness

conveyor belt tightness

The conveyor belt will loosen after running for a while, so it is necessary to adjust the belt tightness.

where to buy shrink wrap rolls or shrink wrapping machines

When looking for a shrink wrap supplier or shrink wrap machine manufacturer, it is advised to shop around.

We recommend comparing 3-4 different companies. Do some research and compare prices, quality of products, lead times, and quality of customer service.

KEEPTOP Packaging is worth your trust.

We are concern the design of pre-production quality and the optimization of production flow, supervise and detection of the whole production process.

It is also equipped with first-class detecting instruments within the industry.

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