Surface cleaning with hot active plasma
15 March 2021
TRADITIONALLY, THE automotive industry has relied on chemical cleaning processes. However, these can be expensive and be environmentally problematic. Maria Laure looks a sustainable and efficient alternative
In production, cleanliness is a key criterion: impurities on the component must be removed in advance so that various process steps can be carried out correctly. This is important for processes such as adhesion and sealing, painting and printing, as well as brazing and welding. The Acerios system from Fronius allows for particularly environmentally friendly and cost-effective surface cleaning using plasma technology.
For example, to be able to join individual aluminum parts to a side wall using spot welding when constructing an automotive body, the surface of the sheets must be freed from foreign particles or film impurities, otherwise a serious lack of fusion would be a possible consequence.
Up until now, the automotive industry has relied on chemical cleaning processes. However, the use, storage, and disposal of the required chemicals is not only expensive, but also problematic in terms of their impact on the environment. Such cleaning processes are also subject to strict safety requirements.
Moreover, nearly the entire component must be immersed in the chemicals, meaning that ultra-precise cleaning is not possible. Overall, this is a laborious and very expensive process
A technology developed by Fronius can help: hot active plasma removes residues quickly and effectively with pinpoint precision. The application areas range from aluminum and steel through to plastic, glass, and ceramic. The Acerios system generates a plasma flame with a temperature of up to 1,000 degrees Celsius, while a robot guides the welding torch over the surface at speeds of roughly 6 meters per minute.
Depending on requirements, entire surfaces or specific areas can be treated. This significantly increases efficiency, as instead of cleaning as much of the surface as possible, Acerios cleans only those areas that actually need cleaning. This immediately conserves resources, again emphasizing the environmentally friendly aspect of this technology due to the absence of harmful cleaning additives.
By using plasma in its welding technology, Fronius has extensive expertise in this area. The company has also been researching possible applications for plasma in surface treatment for almost ten years, the key to this eventually being found in the generation of atmospheric pressure plasma. This is a hot, gaseous, and energy-intensive mixture of atoms, molecules, ions, and free electrons.
When the hot active plasma comes into contact with a surface, the gas flow mechanically cleans while the plasma and resulting heat trigger a chemical process. This combination of a chemical and mechanical process reliably removes organic residues and film impurities.
Simple system design
The Acerios system consists of just a few components:
- Plasma torch with active cooling
- Power source with a power range from 35 to 200 amperes
- Industrial robot which guides the welding torch
- Active process gas control
- Cooling system with varying performance depending on the operating mode (from spot to continuous operation)
The system is compact and can be easily integrated into automated systems and production lines thanks to different interface variants. Pre-defined job settings shorten the training phase and make the device intuitive to use. Acerios is therefore a simple, affordable, and environmentally friendly technology for surface treatment.
Author: Maria Laure, process and application engineering surface technology, Fronius International