Benefits of Choosing Coils Continuous Hot Dip Galvalume Line
Did you know that the continuous hot dip Galvalume line moves the coil material at an incredible speed of 100-200 meters per minute? It is the speed at which the coils are coated with Glavalume alloy. The latest technology for a continuous hot-dip galvalume line promises high production rates by dipping sheets into a 600 °C galvalume alloy. The main purpose is to make the carbon coils highly corrosion-resistant and add aesthetic aspects.
This article will explain what a continuous hot dip galvalume line is, cover the popular methods for carbon coil coating, and explain the top benefits of using the continuous hot dip galvalume line instead of other methods of coil coating.
1. What is a Continuous Hot Dip Galvalume Line?
For high production rates, continuous hot-dip galvalume is a method that applies a coat of alloy metal over the coils. These coils can be carbon steel, lean alloy steel-SPCC/SPCD/SPCE, ST12-ST14, BLC/BLD, or BUSD/BUFD. The coating material is a 55%Al- 43.5%Zn - 1.5%Si alloy. The process is fully automated end-to-end. The coating bonds with the coil material metallurgically.
The Process of Continuous Hot Dip Galvalume Line
The process starts with the uncoiling of the coil. It goes into the cleaning process. The purpose is to remove dirt, grime, oil, or any other unwanted substance from the coils. Then, from there, the coil moves to the annealing process to make the sheet more flexible and remove any oxides from the strip. Now comes the main part where the strip is dipped into the molten galvalume (Al-Zn-Si Alloy) at 600 °C. After the coating, air knives precisely control the thickness to the desired value with ±2 µm thickness accuracy. After that, it is cooled and chemically pretreated to avoid white rust during transport.
2. Other Methods for Coil Coating
To fully understand the benefits of the continuous hot dip galvalume process, it's vital to compare it with the alternative methods for coil coating.
Standard Hot Dip Galvanization
The process uses Zinc material as a sacrificial metal protecting the material underneath. It is semicontinuous or a method that requires batching. The process needs precise control as its non-continuous nature can cause wrapping problems in strips. It forms a Zn-Fe intermetallic layer, but no aluminum. The molten zinc is at 465 °C but has thickness problems.
Electrogalvanizing
Electrogalvanizing uses the electrolysis method to deposit a thin 5-20µm of pure zinc layer. The thickness is accurate, but it cannot apply alloy coating such as galvalume. It consumes a lot of energy and is limited by batch production.
3. Benefits of Choosing a Continuous Hot Dip Galvalume Line
As we now know, the biggest advantage of using the continuous hot dip galvalume line is its high-speed non-stop production. It offers energy-efficient operation with 25% lower energy, 40% reduced dross, and superior process control in comparison to alternatives. Moreover, the layer has the added benefit of aluminum, which enhances aesthetics and corrosion resistance. Here are the top benefits of using continuous hot-dip galvalume.
Precision Process Control and Uniform Coating Application
The process forms a uniform coating over the coil material. The coating that covers the material in just 2 to 5 seconds is superior to any other method that uses zinc. The sealed furnace ensures 100% coating adhesion by removing oxidation on the strip. It leads to the formation of a thin <10µm layer of iron-aluminum-silicon essential for excellent fabrication properties. Through the adjustment of knife pressure, the required client thickness can be achieved.
The galvalume material has self-healing properties with a dendritic microstructure. The coating repairs itself from minor damage while providing 2 to 6 times longer durability in comparison to zinc. The result is a material with an extremely low corrosion rate of 2.097 mpy.
Advanced Strip Processing and Operational Reliability
The end-to-end continuous operation allows the coil to be continuously hot-dip galvalume-lined to ensure speed with reliability. It can handle strips with a thickness lower than 0.6mm without the risk of breakage. The all-radiative tube annealing and closed-loop tension control systems ensure that the material stays intact. The precision of temperature control also leads to better material strength by refining the crystalline structure. The result is 10-15% microhardness.
The process involves the use of a 4-Hi skin-pass mill and a tension leveler. These apply a very light rolling action to the coated strip using two work rolls and two backup rolls. It also reduces the chances of spring-back by 50%.
High Energy Efficiency and Cost Reduction
The coil continuous hot dip galvalume process involves heating of the strip, as mentioned earlier. The radiative tube annealing has an excellent thermal efficiency of 90%. The flue gases preheat the combustion air to 400 °C, reducing gas consumption. Even the initial cleaning chemicals are also heated using the same flue gases. There is no need for an external steam boiler.
The galvalume coating provides effective corrosion resistance properties for coils with lower coating mass. Typically, the material coated is 150 g/m2
Cost-Effective Scalability and Rapid Return on Investment
One of the leading reasons to select any manufacturing technology is to analyze ROI. The non-stop working mechanism of the coil continuous hot dip galvalume line makes it an ideal choice for industrialists. Typically, a line with the annual capacity of 200,000 MT will provide payback in 3 to 4 years. Owing to the growing market of high-quality and premium galvalume-coated coil, the business is expected to grow with the market CAGR of 5-6%.
With periodic maintenance, proper operator training, and inherent properties of the process, zero-defect products can be produced. Its full automation allows minimal human intervention, thus reducing the chances of human errors.
Conclusion
After analyzing the performance of the coil's continuous hot dip galvalume line against other coil coating processes, we can conclude that it's the ideal method. The result of using coils' continuous hot dip galvalume line is high production rates, precision control, and cost savings with 25% lower energy, 40% less dross, and superior automation over alternative coating systems. The process is scalable and confirms the premium-grade coil requirements of clients globally.
If you are looking to start a Coils Continuous Hot Dip Galvalume Line, then consider contacting Hito Engineering to customize your line for maximum uptime and turnkey performance.
