Corona treatment of metal sheets 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 sheet metal strips thanks to the highest quality and safety standards. Achieve optimal and uniform pretreatment of your sheet metal. Rely on the market leader for maximum process reliability and efficiency.
Corona treatment of metal sheets
Wherever sheets of metal (painted and unpainted) are laminated or coated, adhesion is an important issue.
In sandwich panel production in particular, the painted inner side of the sheet metal outer skin is pretreated with Corona to improve the adhesion of the foam. The switch to foams with a higher flash point means that adhesion must be further increased. In addition, bare sheet metal strips can also be cleaned with corona pretreatment. However, this is only possible up to a certain degree of contamination.
What is special about the pretreatment of metal sheets
Unlike plastic films, pretreatment rollers cannot generally be used for the pretreatment of sheet metal. The grounded sheet metal web itself becomes the counter electrode. We developed this special system in collaboration with one of the world’s largest sandwich panel manufacturers. Several of these systems are in use there, offering reliable production and low wear.
How was our system optimized in this regard?
Roller pairs at the inlet and outlet of the system precisely define the distance between the sheet metal web and the ceramic electrodes and prevent them from being damaged by accumulated sheet metal.
The ceramic electrodes are equipped with stainless steel cores. There are no adhesives. Unlike electrodes that are bonded and filled with metal powder, AFS electrodes are many times more stable.
Our quick-open function provides additional protection for the ceramic electrodes. In the event of a sheet splice, which is either announced by a signal from the line or detected by an interrupted laser beam, the system opens and closes again after the splice has passed through. Sheet metal webs can carry metal particles that remain on the back of the Corona electrodes. In the worst case, this can lead to flashovers or damage. The optimized AFS extraction system can prevent this to a large extent. Moreover, the electrode holders are additionally shielded.
Easy maintenance with high accessibility.
To enable convenient cleaning and easy replacement of the electrodes, the middle section of the system with the ceramic electrodes can be easily opened. Inspection panels on the side wall of the electrode chamber also allow for quick cleaning in between.
System Highlights
- Safe and easy operator access for adjustment and cleaning work.
- All common digital interfaces, Profi-Bus, Can-Bus, Profi-Net, Ethernet, etc.
- CE conformity.
- No use of plastic in insulators or housings. AFS uses only ceramic insulators. Our design allows for sufficient air gap between the electrode and the side covers.
- Fast opening for splice operation.
Technical details
| Attribute | Details |
|---|---|
| Application | Metal sheet treatment (e.g. sandwich panels) |
| Working width | 600 - 2000 mm |
| System versions | Single sided (treatment top side or bottom side) |
| Electrodes | max. 7 high output ceramic electrodes |
| Line speed | up to 100 m/min |
| Generators | 1 – 14 kW, depending on working width |
| Technical highlights | - Customer specific designed Corona-Station - Stable and safe path through grounded guide rollers - High ceramic electrode protection - Robust, reliable and compact design for easy cleaning and maintenance - High efficiency corona generators results in low operating costs and improved ROI Generators withstand strong power fluctuations - Fast Open (splice) on web thickening (option) |
System overview
Pneumatic cylinders open the system even during splicing.
Hinged top for easier access during maintenance work.
High-voltage transformer:
All high-voltage cables are laid inside the workstation.
Suction nozzle:
Optimized suction prevents chip formation behind the electrodes as far as possible. Ozone produced during treatment is reliably extracted.
Easy insertion of the sheet metal strip when the system is open.
Ground roller pairs at the inlet and outlet of the system define a precise spray gap regardless of the material thickness. They also ensure even pressure to guide the sheet metal safely through the station.
Closed bar with ceramic electrodes and protective cover.
Ceramic electrodes
Our ceramic electrodes are the result of decades of experience in the field of corona pretreatment.
The single-sided corona sheet metal pretreatment is equipped with four ceramic electrodes (see image), for example. These are connected to the high-voltage supply of the attached transformer. Conductive webs such as sheet metal can only be pretreated with ceramic electrodes.
The protective housing completely encloses the electrode. This enables complete extraction of the ozone and prevents radio interference as far as possible.
AFS generator
Operation at the resonance frequency
AFS generators always run at resonance frequency. In the event of deviations, the frequency is adjusted until the phase shift returns to zero degrees. This means that the entire electrical oscillating circuit is constantly monitored and regulated to ensure that reactive currents are kept to a minimum and the systems achieve maximum efficiency.
The diagnostic and operating memory
Our operating memory has proven to be a helpful tool, storing the last 200 changes with a time stamp, thus making the processes transparent. When was the station started or when were performance adjustments made? The diagnostic memory displays the last 200 messages in plain text, enabling continuous quality assurance of production.
Climate control
Studies have shown that a temperature increase of just 10 °C significantly shortens the service life of electrical components. We offer a wide range of climate control solutions, from passive cooling to compressor-based cooling units. We would be happy to determine the optimal climate control solution for you.
Remote control via BUS
All generators can be equipped with remote control. Customers can choose between a remote control (FB), a remote control unit (FS04/05), or common field buses such as Profi-Bus/Profi-Net, CAN-Bus, etc. to conveniently integrate the station into their overall system.
High reliability in the event of power fluctuations
In countries where the power supply is subject to occasional fluctuations, many generators have problems maintaining a constant output. This is where the AFS generator can demonstrate its potential, easily compensating for slight to moderate fluctuations.