Although the name "Hatschek Machine" and "Flow-on Process" may be unfamiliar to you, these methods are similar to how coffee is made: there are espresso machines and pour-over coffee machines, both of which have a particular group of enthusiasts and many advantages.
The Hatschek Machine-The "Founding Father" of Fiber Cement Boards
In 1900, the Austrian engineer Ludwig Hatschek invented the cylinder-mold forming method; this marked the very beginning of the history of fiber cement boards. Believe it or not, more than a century later, this "old workhorse" is still diligently at work in major factories around the globe.
Its operating principle is somewhat akin to making a handmade layered pastry. The slurry is diluted to an extremely low concentration (ranging from just 2% to 10%) and flows into a series of rotating mesh cylinders. Each mesh cylinder picks up a thin layer of material from the slurry; typically, three to six cylinders are arranged in series, stacking layer upon layer. Finally, these layers are wound onto a forming drum and pressed into a dense, solid board slab.
The greatest advantage of this process is its high density. Boards produced via the Hatschek method possess an extremely compact internal structure, with densities capable of exceeding 1.2–1.5 g/cm³. Furthermore, the orientation of the fibers within the board can be controlled-aligned with the primary direction of structural stress-resulting in highly efficient fiber utilization. Consequently, boards produced by this method are inherently well-suited for demanding applications such as exterior walls and curtain walls, where rigorous strength requirements are paramount.
Of course, the system is not without its flaws. The equipment features a complex structure and requires substantial upfront investment; moreover, due to the multitude of stacked layers, there is occasionally a risk of delamination. Additionally, the low concentration of the slurry necessitates the processing of vast quantities of recirculated water during production, resulting in a relatively higher volume of wastewater generation.
The Flow-on Process-The Up-and-Coming Contender
The primary distinction between the Flow-on Process and the Hatschek method lies in the fact that the slurry does not pass through mesh cylinders for filtration; instead, it flows directly from a headbox and spreads out onto a felt conveyor belt-much like spreading batter to make a pancake. The slurry concentration used in this process is also significantly higher than that of the Hatschek method, typically ranging between 10% and 20%.
The advantages of the Flow-on Process are eminently practical. The equipment features a simple structure and requires a low initial investment. Furthermore, the production process involves minimal water recirculation, resulting in low emissions of wastewater and solid waste, making it a more environmentally friendly option. Moreover, its high production efficiency makes it ideal for large-scale mass production, allowing for a daily output of several thousand square meters with ease.
However, the slurry-casting method does have its limitations. Because the slurry is applied directly without undergoing the fine filtration step provided by the wire-wheel forming process, the resulting slabs lack the flatness and density achieved by the sheet-forming method. Consequently, the slurry-casting method is primarily used to manufacture medium-density boards (6–15 mm in thickness), making it suitable for applications-such as interior partition walls and suspended ceilings-where density requirements are not strictly critical.
How to Choose? It Depends on Your "Taste"
To be honest, neither of these two processes is absolutely superior to the other; the key lies in what you intend to produce.
For manufacturing products with high structural requirements, like exterior walls or curtain walls, the method of sheet-forming is generally the better option. It provides a high level of density, outstanding strength, and very efficient fiber utilization. Besides, it is highly resistant to wind pressure and impact. However, it requires a major investment in equipment and results in longer production cycles, so you need to make sure your finances are up to it.
For cost-effectiveness and high production, slurry casting method could be the option if you are making medium-density products. Besides low cost of equipment, it also has a short learning time, produces a large quantity, hardly creates wastewater and is more lenient environmentally.