When you manufacture or use plastic flexible packaging, achieving a strong and perfectly aligned heat seal is critical. A poor or crooked seal can lead to leaking pouches, reduced shelf life, product contamination, and even customer complaints or returns.
One of the most overlooked reasons for this problem is unstable film friction coefficient. In this article, we’ll explain why film friction is so important in the heat sealing process, the main reasons it becomes unstable, and how to fix it to ensure consistently high packaging seal quality.
Why Film Friction Coefficient Matters in Packaging
The friction coefficient of a plastic packaging film determines how the film moves through the packaging machine.
If the friction is too high, the film may jam or stretch.
If it is too low or unstable, the film may slip or misalign, resulting in seal misalignment or incomplete heat sealing.
Consistent film friction ensures smooth film feeding, proper positioning, and a reliable heat-sealed joint every time.
3 Major Causes of Unstable Film Friction
1. Packaging Material Quality
Your flexible packaging film itself is often the first thing to check.
Uneven surface treatment – If corona treatment or coating is not uniform, different areas of the film will have different slip properties, affecting seal alignment.
Raw material variation – Changes in resin formulation or slip additives can alter the film friction coefficient and affect heat sealing performance.
2. Environmental Conditions
Your production workshop environment directly affects how films behave.
High temperature – Excess heat can soften the film, changing its slip and stretching characteristics.
High humidity – Moisture can form a thin layer on the film surface, causing inconsistent film feeding and unstable seal quality.
3. Packaging Machine Condition
Even with perfect film, a packaging machine can cause problems.
Dirty rollers – Dust, glue, or film residue can change the contact surface, affecting friction.
Worn components – Uneven roller wear can cause the film to skew and create misaligned heat seals.
How to Prevent Seal Misalignment and Improve Packaging Quality
Source consistent, high-quality packaging films from a reliable supplier who ensures proper surface treatment and stable friction properties.
Control temperature and humidity in your production area to maintain stable film behavior.
Schedule regular machine maintenance to keep rollers clean and in good condition, ensuring smooth film transport.
By managing these factors, you can significantly improve seal quality, reduce product waste, and increase packaging line efficiency.
At SKYUTILITYPACK, we work with customers worldwide to solve heat sealing and film friction challenges. Whether you need a custom flexible packaging film with a stable COF (coefficient of friction) or technical advice to optimize your sealing process, we can help you achieve consistent, professional packaging results.
flexible packaging
plastic packaging film
film friction / friction coefficient
heat sealing / heat-sealed joint
seal misalignment / seal quality
packaging machine maintenance
improve packaging efficiency
