The surface of the zinc melt, usually heated to 440 °C up to <460 °C (normal temperature galvanizing), must be free from zinc ash before the component is immersed or removed.
The stripping of the zinc ash floating on the zinc melt surface occurs longitudinally along the zinc kettle.
The immersion of the components in the zinc melt should occur continuously at a steep immersion angle.
The aim should be a rate of at least 5 m/min under consideration of the floating behavior of the component.
The components must remain in the zincmelt until the flux has completely boiled off or a temperature balance has been achieved.
Depending on the kind and form of the component, a rule of thumb may be 30 s up to 1.5 min per mm wall thickness. During the galvanizing process, the component should be moved in a way that the resultant zinc ash is able to float off.
The removal of the galvanized component from the zincmelt has to occur relatively slowly to ensure good zinc drainage and a smooth surface (approximately 0.5 to 1 m/min, depending on the design of the component).
A stripper must be used to keep the surface of the zinc melt clean at all times.
Converging zinc drips and swellings on the underside of the profiles can be removed by a stripper or through regulated compressed air blowing.
The zinc consumption per ton of substrates to be galvanized depends on the chemical composition of the steels, in particular on their Si and P content (see below), which varies between 5 and 8% in normal assortments.
As zinc is consumed, new zinc must be added to the zinc melt.
In order to guarantee the nominal aluminum content, it is recommended to add it in the form of a ZnAl alloy evenly distributed over the kettle.
Even distribution is important in order to avoid uncontrolled addition of Al that may result in ungalvanized spots (black spots) on the galvanized component. The Al content of the melt ensures the zinc’s inherent shine of the coatings and leads, in the case of dead steel, to a slightly decelerated layer growth.
Moreover, aluminum increases the naturally limited bending strength of zinc coatings on thin sheets. Aluminum in the melt is consumed considerably faster than zinc (ratio of approximately 5:1). This is in particular due to its preferred oxidation on the melt’s surface and the enhanced reaction with the flux.
Q: What is a Hot Dip Galvanizing Line?
A: A Hot Dip Galvanizing Line is a continuous industrial process used to coat steel or iron with a layer of zinc to protect it from corrosion.
Q: How does a Hot Dip Galvanizing Line work?
A: In a Hot Dip Galvanizing Line, steel or iron materials are cleaned, pickled, and then dipped into a bath of molten zinc. The zinc coating forms a metallurgical bond with the steel, providing excellent corrosion protection.
Q: What are the benefits of using a Hot Dip Galvanizing Line?
A: The main benefits of using a Hot Dip Galvanizing Line include superior corrosion protection, extended lifespan of steel products, low maintenance requirements, and a smooth, durable finish.
Q: What types of steel products can be processed with a Hot Dip Galvanizing Line?
A: A Hot Dip Galvanizing Line can process a wide range of steel products, including structural beams, pipes, and various fabricated components.
Q: Are there any environmental considerations when using a Hot Dip Galvanizing Line?
A: Yes, environmental considerations are important when operating a Hot Dip Galvanizing Line. Efforts are made to minimize emissions, manage wastewater responsibly, and ensure compliance with environmental regulations to reduce the impact on the environment.