When poor tracking, slippage, and other problems occur on flow wrappers, fin wheel pressure or temperature is often increased to get the machine up and running again.
These adjustments, however, may only be a temporary fix that could cause more severe problems in the future.
This Greener Tech Bite presents a systematic approach you can use to:
- Optimize Fin Wheel Adjustments
- Troubleshoot Problems
- Implement Preventative Maintenance
Follow these procedures to ensure consistent package quality and productivity.
Most wrappers utilize at least two, and often three, pairs of fin wheels. The first pair, typically unheated, works primarily to draw the packaging material tube forward through the wrapper. The second and third pairs seal the fin and guide the tube forward.
The same four steps can be followed to solve fin wheel problems and for preventative maintenance, which should be performed every six months.
Inspect
Check Bearings
Test Sealing Pressure
Check Adjustments and Design
1. Inspect
Begin by removing the cover plates and making a visual and physical inspection.
Damage, Wear, Sharp Edges
Rotate each pair of fin wheels and check the sealing surface for damage and wear. Make sure their top edges have not grown sharp from rubbing against the cover plate.
Clean
Clean any packaging material or product that has built up on the sealing surface.
Replace fin wheels that are worn, damaged, or that can’t be properly cleaned with a new, matched pair; never replace just one fin wheel.
2. Check Bearings
Even with new fin wheels, slippage and poor tracking can continue if the bearings are worn. Bearing failure is often caused by excess pressure and heat adjustments that were made to compensate for worn fin wheels.
Using protective gloves if the fin wheels are hot, grasp and try to rock each fin wheel backward and forward, between the product feed and the product discharge. Any freedom of movement indicates worn bearings that should be replaced.
3. Check Sealing Pressure
Fin wheel wear that was not detected during the visual inspection can still cause problems.
Bring the fin wheels to operating temperature, and engage each pair together with a doubled piece of packaging material between them.
If the material can easily be pulled out, make sure the tension between the fin wheels is within normal operating parameters. If pressure is too low, make corrective adjustments to increase it. If pressure settings are correct, the fin wheels are likely worn and need to be replaced.
Worn bearings will also yield this result, so be sure to follow step 2 before doing this test.
4. Check Adjustments and Design
If problems continue after following the first three steps:
Temperature
Make sure that fin seal temperature settings are within the proper range for your flexible packaging material. Excess heat causes slippage problems and can distort and even melt through the fin seal.
Tilt
Next, check the tilt adjustment of the fin wheels. Additional tilt, where the infeed end of the fin wheel is slightly higher than the discharge end, gives the fin wheels more “bite” and helps them draw the tube forward.
This tilt also pulls the material downward to create tighter packages.
Make this adjustment with care.
Too severe an angle can cause the fin wheels to rub against the cover plate and develop sharp upper edges that cut the package.
Gripper Grooves
If problems still persist, install fin wheels with gripper grooves for the first, leading pair. Gripper grooves provide extra tension to prevent slippage and tracking issues.
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Dura-Therm
Some flexible packaging materials are poor thermal conductors, such as paper and some thicker structures.
For these applications, fin wheels made from Dura-Therm provide more consistent, responsive heat transfer to prevent temperature fluctuations that cause sealing and tracking issues.
Product Presentation & Package Formation
Problems that persist after following these troubleshooting steps are often caused by upstream issues.
Learn more from our post and video on Product Presentation and Package Formation.
If you’d like technical assistance with fin wheel or other packaging problems on flow wrappers or vertical baggers, contact Greener Corporation.
We provide integrated parts and technical services worldwide.
