Electrolytic galvanizing lines
ANDRITZ Gravitel systems have set the trends in electrolytic galvanizing technology (EGL) for coating steel strip with zinc or zinc alloy on one or two sides. With good cause, manufacturers of galvanized steel opt for this technology.
The Gravitel (Gravity for Electroplating) process takes place in a vertical cell, where the strip runs with narrow clearance between two moveable anode boxes. The anode plates are attached to the anode boxes. The anodes are made of titanium sheet coated with conductive iridium oxide. The electrolyte flows into the gap between anode and strip and is accelerated by gravity up to a speed of 5 meters per second. High electrolyte flow enables high-capacity electroplating at a current density of up to 180 amps per square decimeter.
The Gravitel process has proven to be a reliable system for the production of highest quality electro-galvanized steel strip for automotive exposed sheet, as well as household and office appliances, such as air conditioners, microwaves, washing machines, flat-screen TVs, computers, and so on.
- High product quality, high availability
- Low power consumption, low overall cost
- Low use of line length
- Low dent (needle crystals on strip edge) development
- No edge over-coating, no wrap around at strip edge
(no need for edge masking)
- Dimensionally stable anodes
- Engineering based on experience
- Energy- and zinc-saving operation with minimum downtimes
- Many years of experience and outstanding reference situation
Corresponding E&A models
ANDRITZ Line Master
Based on the primary coil data and the requested coating weight, the coating algorithm continuously calculates the set point for process speed and rectifier current for each cell in order to maximize the output of the EGL. A closed loop control system corrects the calculation based on the zinc coating weight measured online. The dissolving calculation provides the set point for the speed of the zinc dissolving pump.