A packaging line can be technically tuned to perfection, yet still experience regular downtime. In many cases, the cause does not lie with the machine, but with the properties of the film used.
Runability, or the degree to which a film can be processed stably and reliably on an automatic packaging line, is determined by a combination of material properties, machine settings and the packaging application. A FFS film what performs excellently on one line can actually cause disruptions on another machine.
Which film properties have the greatest influence on the performance of automatic packaging machines?
1. Coefficient of friction (COF)
The coefficient of friction (COF) determines how easily film moves over machine parts.
When the COF is too high, it can be difficult to transport the film through the machine. If the COF is too low, however, the film may start to slip, making positioning and sealing less accurate.
A well-adjusted COF contributes to:
- Stable foil feed
- Constant packaging speed
- Less machine downtime
- Reliable positioning during packaging
2. Thickness tolerances
It is not just the thickness of the film that is important, but above all its consistency.
When the thickness varies across the roll, this can lead to differences in tension, sealing behaviour and film guidance. Especially on high-speed packaging lines, even minor deviations can affect process stability.
Precise thickness tolerances ensure:
- Continuous processing
- Even seal lines
- Reduced process variation
- Reliable machine performance
3. Rigidity of the film
The stiffness determines how the film behaves during transport and forming.
If the film is too flexible, it may crease or deviate from the desired path. Conversely, if the film is too stiff, it may be difficult to shape or cause unnecessary tension during the packaging process.
The right balance helps to:
- Good film guidance
- Less creasing
- Better dimensional accuracy
- Stable processing at high speeds
4. Claim behaviour
During transport within the machine, the film is constantly under tension.
If a film stretches too much or, conversely, not enough, this can affect the registration, the seal position and the dimensions of the packaging.
Controlled stretching behaviour ensures:
- Precise packaging
- Constant dimensions
- Reliable print tracking
- Fewer product rejections
Sealing behaviour
The performance of packaging is largely determined by the quality of the seal.
Factors such as the following play a role:
- Sealing temperature
- Sealing window
- Hot tack
- Seal Strength
an important role.
A film with a wide sealing window often offers greater process reliability, especially when small temperature fluctuations occur during production.
6. Surface treatment
For printed packaging, a good surface treatment is essential.
Proper corona treatment ensures good adhesion of inks and coatings, but also helps to ensure stable processing during the production process.
A properly treated film helps to:
- Achieving consistent print quality
- To improve the lighting
- to limit production waste
7. Material build-up
The composition of the film also has a major influence on the runnability.
Modern mono-PE structures can nowadays combine excellent processing properties with a high degree of recyclability.
Through the right combination of raw materials and layer structure, a film can be tailored to:
- High packaging speeds
- Specific products
- Different FFS processes
- Future PPWR requirements
Why runability is about more than just the film
Although foil properties play a major role, runability is always determined by the combination of:
- The packaging machine
- The product
- The foil
- The machine settings
- The environmental conditions
Therefore, the ultimate suitability of a film is assessed not only in a laboratory, but also under practical conditions on the packaging line.
Frequently asked questions about packaging film runability
What does runability mean?
Runnability indicates how stably and reliably a film can be processed on an automatic packaging machine, without unnecessary downtime or quality issues.
Which film property has the most influence on the performance of a packaging line?
That varies by application. In practice, the coefficient of friction (COF), thickness tolerances, sealing behaviour and stretch behaviour are often decisive for a stable packaging process.
Is a thicker film always better for runability?
No. Performance is determined by the total material structure, the formulation and the processing properties. A thinner, optimised film can in many cases even perform better than a thicker variant.
Why does the processing differ per packaging machine?
Every packaging machine works with different transport, sealing and tension systems. As a result, the same film can perform differently on different machines.
How does KIVO help optimise runability?
KIVO develops packaging films in which material properties, packaging machinery and application are considered as a single entity. By working with customers and machine manufacturers, films can be tailored for both reliable processing and future requirements regarding recyclability and PPWR.
Conclusion
A stable packaging line starts with the right film. Properties such as COF, stiffness, stretch behavior, thickness tolerances, seal performance, and material structure largely determine how efficiently an automatic packaging machine operates.
By incorporating these characteristics into the development of packaging from the outset, unplanned downtime, product rejection and unnecessary packaging costs can be reduced. At the same time, scope is created to future-proof packaging with recyclable mono-materials that align with the requirements of the PPWR.
Curious which film properties affect the performance of your packaging line? Contact one of KIVO's specialists for an analysis of your packaging application.
