The electrophoretic painting is one of the most progressive technologies of surface finishing of metal products. The development of the electrophoretic technology is led by the automotive industry since all car producers focus on corrosion resistance of bodies and other components.
High quality of surface finishing, together with favorable economic and ecological conditions, predetermined this technology for use also in other branches of mechanical engineering and consumer industry.
Cataphoresis is a coating technology for the surface preparation of metal which requires significant anticorrosive protection. Painted subject is connected as a cathode in direct-current field of electrolyte (aqueous paint solution) and attracts cations from paint. Electrophoretic cells (flat or tubular) are connected as anodes and they are used to keep an equilibrium concentration in paint bath.
The high corrosion resistance of electrophoretic deposition allows increasing the lifetime of any metal parts. First flat and heavy anodic or cathodic cell type was continuously replaced by new lightweight tubular cell. Small and light design allows decrease the service time and shutdown.
Failure of one small tubular cell has much less negative effect on coating process than failure of one big flat cell. Currently the two tubular cells are on the market, the welded or glued cell from flat sheet membrane and extruded tubular membrane. Each type has some advantage and disadvantage which are described in this article.
Czech company MEGA-TEC produce complete cells and its own electrophoretic membranes as the only european producer and as the only world-wide producer of all types of electrophoretic cells:
- Flat and semi cell custom made with ability of to offer all necessary spare parts such as electrodes, seals and fasteners. The ion-exchange membrane in flat sheet form is stretched between the anode and the frame. Standard RALEX Membrane AMH5E-HD has been in service since 1996.
- Tubular cells with d81mm welded membrane: The membrane is installed around the anode by putting on a perforated plastic tube. RALEX Membrane AMH6E-HD as the latest generation of e-coat membrane has been used since 2013.
- Tubular cells with d65mm extruded membrane: The membrane in a tubular form is installed around the anode by fixing in the bottom cap and top head. RALEX Membrane AM-XT has been developed in 2012.
