In the paper industry, steel is indispensable; in fact, it is used for several purposes: construction of machinery, equipment and essential components for paper production. Steel provides durability, strength and ability to withstand the production process and ensures efficiency, safety and reliability in paper mills.
Where is steel essential in a paper mill?
Montanstahl produces high-quality steel profiles used in a variety of industries, from the military to the nuclear industry, via the medical and food industries.
However, because steel is an extremely versatile and durable material, even the paper industry cannot do without it. In a paper mill, in fact, steel is used for the production of machinery, equipment and components essential for papermaking.
One of the main uses of steel in this industry is to build the machines that convert pulp or other materials into paper. These machines require components that are strong, durable and can withstand the weight and pressure of the entire production process. Steel meets these requirements through its use in the construction of parts such as cylinders, blades, rollers and gears.
In addition, steel is also used in the construction of auxiliary equipment and devices, such as pumps for transporting water and chemicals used during the papermaking process, storage tanks, and pipes for transporting materials.
The use of steel in paper mills is also essential to ensure the safety and reliability of machinery, as steel components are able to withstand the mechanical and thermal stresses typical of the papermaking process, reducing the risks of malfunctions and failures that could compromise the entire production cycle.
What kind of steel is used?
As mentioned, steel is a widely used material in the construction of papermaking machines, particularly for the rollers that are used to spread the pulp and form the paper surface.
The type of steel used for these rollers depends on the specific requirements of the production process, particularly the speed of rotation of the rollers and the pressure to which they are subjected; in general, they are characterized by high mechanical strength and hardness, so as to ensure a long service life and good ability to withstand repeated stresses over time.
The steel alloys most commonly used for paper machine rollers include carbon steel, stainless steel, and steel alloyed with other elements, such as chromium and molybdenum.
Carbon steel is a versatile and cheaper alloy that offers good mechanical strength and hardness, but is, however, subject to corrosion and plastic deformation, which can reduce the life of the roller.
Stainless steel, on the other hand, offers greater corrosion resistance than carbon steel but is less hard and resistant to plastic deformation; it is mainly used in the parts of rollers that come in contact with water and paste.
Finally, steel alloyed with other elements, such as chromium and molybdenum, offers greater corrosion resistance and hardness than carbon steel and stainless steel. This alloy is often used for the rollers of high-speed papermaking machinery, where pressure and temperature are high.
In each case, the choice of which steel alloy to use depends on the specific requirements of the production process and the trade-off between mechanical strength, hardness, and corrosion resistance.
As Montanstahl worked in this area
We manufactured special profiles of 25x25x3 mm (similar to the size of a one euro coin) with very small welded corners for a paper mill; specifically, the profile would be used in paper winding machines.
These machines are divided into two parts: felting area, where the pulp loses water and the wet sheet is formed; drying area, where the profile is used, in fact here the sheet is dried, further smoothed and rolled onto a reel.
The first difficulty was the welding of this material; the heat of the laser causes changes in the structure of the material and affects its corrosion resistance.
From the production point of view, another problem was the possible twisting of the bar: the laser force could create random twists along the entire length of the bar, which could not be adjusted because of the small geometry.
We solved these problems by adjusting the laser power and speed to ensure the high levels of corrosion resistance and maintain the straightness of the bar.
The angle profiles produced are made of EN1.4410 stainless steel, belonging to those materials called duplex, which are distinguished from other subgroups of stainless steels by a particular chemical composition that determines their characteristics, which we will explain shortly.
The Duplex: characteristics and why it was chosen
Duplexes are ferritic and austenitic: in fact, they have a balanced content of ferrite and austenite (about 50-50).
Ferrite gives them high mechanical properties and increased stress resistance; austenite, on the other hand, makes them more ductile and improves their corrosion resistance.
There are different types of duplexes, which differ in their chemical composition; in fact, other elements (including molybdenum, chromium and nickel) are also present in duplexes in different percentages, which further influence the material properties. In the case of duplex 1.4410, chromium and nickel are present in larger amounts, giving it greater corrosion resistance than other types of duplexes, which is why it is also called super duplex.
This material is mainly used in the oil and gas industry, offshore, textile, paper and construction industries; for chemical tank production; and in general, in high chloride environments.
In summary, stainless steel is an essential material in the paper industry because of its strength, durability and ability to withstand the mechanical and thermal stresses typical of the production process.
Its presence is essential to ensure the efficiency, safety and reliability of the machinery and equipment used in a paper mill.