Corona Pre-treatment for cast film in Detail
With over 40 years of experience, AFS systems are among the best-selling corona treatment stations in the world. They guarantee reliable surface modification for cast films thanks to the highest quality and safety standards. Achieve optimal and uniform pretreatment of your cast films even at the highest speeds and widths. Rely on the market leader for maximum process reliability and efficiency.
AFS Corona Treatment Systems
In recent years, cast film lines have been built to be faster and wider. Widths of over five meters and production speeds of around 400 m/min are no longer uncommon. Polypropylene films are often produced on cast film lines, which can only be pretreated with a high energy input and very often only to a surface energy of 44 to 46 mN/m. The PP films are usually treated on one side only, either the front or the back. Pretreatment of the other side (back effect) is almost always undesirable and can lead to problems in subsequent processes. This places special demands on the corona pretreatment system.
The generators
The high energy input at high speeds and large widths results in high generator outputs. Our module generators with a maximum output of up to 144 kW easily cover the required power range. With a single generator with switchover unit, you can select the side to be pretreated either directly on the generator or remotely via the BUS connection. If both sides are to be pretreated, we recommend the double generators from AFS for full flexibility.
The pre-treatment station
In order to place the high generator outputs on the film without damaging the heat-sensitive films, many good individual solutions are required in the Corona pretreatment station. Corresponding error patterns include, for example, wrinkles, which can lead to a backside effect and impair the pretreatment result. Optimal ventilation of the electrode chamber prevents excessive heating of the electrodes and thus also of the film.
In addition, water-cooled pretreatment rollers support adequate heat dissipation. The design of our round electrodes has proven to be optimal after more than 40 years of experience with cast film lines. The roller coatings used have also been optimized over many years in terms of dielectric properties, efficiency, and robustness. To avoid a back effect caused by an air cushion between the pretreatment roller and the film, our nip rollers ensure that the film fits perfectly against the treatment roller thanks to their precisely calculated crown.
The transformers
The transformers are compactly mounted on one side of the corona station to keep the high-voltage connection to the electrode as short as possible. This minimizes electrical losses in the high-voltage circuit and avoids wear parts, enabling many years of trouble-free operation.
exhaust fans
Our exhaust fans are explicitly ozone-resistant and ensure compliance with occupational exposure limits around our plant. Noise emissions can be significantly reduced with an optional silencer.
Technical details
| Attribute | Details |
|---|---|
| Application | Cast film treatment |
| Typical working width range | 2000 - 5000 mm as standard |
| System variants | One-sided, two-sided, or alternating |
| Electrodes (depending on system type) | - Stainless steel tubular electrodes - Ceramic electrodes |
| Dielectric on the pre-treatment roller | - Silicone - Ceramic |
| Line speed | Up to 400 m/min, higher speeds are possible |
| Options | - Pressure roller - Drive for treatment roller - Water cooling - Stretcher roller |
| Technical highlights | - The best electrode holders on the market (AFS-Patent) - External spray gap adjustment - Specific station design according customers requirements - Robust, reliable and compact design for extremely easy cleaning and maintenance - The high efficiency of the corona generators benefits the user in terms of investment and operating costs |
Typical Options for Cast film lines
Corona-Pro
For very low corona outputs, the generator can automatically activate the Corona-Pro mode. This enables homogeneous power distribution across the entire electrode width and thus ensures uniform pretreatment results even at very low speeds.
Wet start
The wet start function dries the station electrically and prevents failures due to flashovers.The system is ready for use again in a short time, as any condensation that has formed evaporates very quickly.
LookBack
The LookBack function displays all process parameters graphically as a diagram on the generator display. An interface is available for further data evaluation.
System overview
Clear control panel with multifunction rotary knob and touchscreen.
Precise spray gap adjustment via AFS electrode adjustment units (scalable from 0.9 to 2.3 mm).
High-voltage transformer: All high-voltage cables are laid inside the Corona station.
Curved contact/nip rollers guarantee optimally distributed contact pressure for pre-treatment without any residue on the reverse side.
Well-designed cassette concepts with targeted airflow ensure optimal pre-treatment results.
Maximum operator protection possible thanks to various protective devices.
System highlights
Maximum safety
High voltage, a fast-moving web of goods, and many moving parts in the system increase the risk of injury to operating personnel. Detailed risk analyses were used to identify the hazards and eliminate them by means of covers or other measures, such as an optionally available complete enclosure for the system. Even in conditions of high humidity, our generously calculated flashover distances to our all-metal electrode housing ensure safe and error-free production.
Highest quality standards
At our site, we manufacture in modern assembly halls to ensure our usual high quality standards. The energy requirements of the assembly hall are met in an environmentally friendly and sustainable manner using our own solar power.
Ceramic insulators
AFS uses only ceramic insulators. Our design allows sufficient distance between the electrode and the side covers. This is a major advantage over plastic housings, as these absorb salts and moisture over time, which can lead to frequent flashover failures and long cleaning times. In addition, cleaning itself is made easier by improved accessibility.
Systems for clean rooms
On request, we can even manufacture entirely in stainless steel. This allows complex clean room requirements to be met.
AFS generators for maximum production reliability and productivity
Our latest generator technology combines reliability and efficiency with optimal process integration at low operating costs.
Insulated airflow cooling for electronic components to avoid maintenance-intensive filter cleaning in our S/SE series.
The new M generator series from AFS is based on a modular approach that ensures your production reliability and productivity. The number of modules depends on the desired maximum power and can be increased for additional redundancy.
- Modern design with a clear and intuitive user interface.
- All AFS generators feature a comprehensive operator action and error message log in plain text and in multiple languages.
- The internal process parameters are monitored using an “early warning system” that enables corrective measures to be taken without any loss of production.
- The M2 generator type allows individual power adjustment at each electrode, optimizing investment costs and space requirements compared to two separate generators.
- All available remote control interfaces, such as ProfiBus, Can Bus, Profinet, Ethernet, etc.
- Changing a module is easy and takes just a few minutes. Step-by-step instructions are included in our documentation. No special tools or skills are required.
- For demanding climatic conditions, we offer suitable additional cooling units that have proven themselves over time.
