Particularly in automotive construction and in the aerospace industry, aluminum plates and sheets are increasingly utilized due to their lightweight yet high strength properties. Without these innovative aluminum materials, achieving the imperative of low weight for structural parts or exposed applications would be challenging. Many applications necessitate the treatment of cold-rolled aluminum strips through annealing combined with fast cooling to attain formability and requisite material strengths.
In line with this demand, SMS group provides suitable heat and chemical treatment lines, ensuring precise treatment processes for various materials. These lines not only facilitate material heat treatment but also incorporate an additional chemical treatment for strip surfaces. Covering a broad spectrum of materials, our lines accommodate thicknesses ranging from 0.2 to 4.5 millimeters, with strip widths exceeding 2.5 meters.
Complementing this offering are our advanced color coating lines, pivotal for industries including food packaging, architecture, household appliances, and furniture. These lines are instrumental in applying high-grade coatings to aluminum strips, enhancing their durability, corrosion resistance, and visual appeal. At SMS group, we provide comprehensive color coating solutions tailored to meet diverse application requirements, ensuring optimal performance and quality across all processes.
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Heat and chemical treatment lines (HCTL)
From cold rolled to automotive and aeroplane strip products
The use of aluminum as a lightweight construction material in automobiles and also in the aviation industry continues to be on the rise. Subsequent to the cold rolling process, the aluminum sheets have to undergo a heat treatment to regain formability as well as the required material strengths. Especially the heat treatment and the cooling of the strip play a major role. To increase flatness the strip has the possibility to run through a tension leveler. The strip surfaces must be cleaned before they are coated. The chemical treatment prepares the strip for transportation and further processing. These processes can take place separately in different facilities or combined in a heat and chemical treatment line, which can provide financial benefits.
Main process steps:
- Annealing and cooling
- Tension leveling
- Cleaning
- Chemical treatment
- Aging
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Color coating lines for aluminum (CCA)
High-grade coatings in efficient lines
In color coating lines the aluminum strip is covered with a high-grade coating. One example of its use is in the food industry, such as for beverage cans. Further major fields of application are the construction and automotive industries as well as producers of household appliances. The different fields of application need different protective surface finishes and constant further development of the coatings. SMS group offers solutions for all coatings and market requirements as well as sophisticated process components for the process steps crucial for quality.
Main process steps:
- Tension Leveling
- Cleaning
- Chemical Coating
- Color Coating
- Curing
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Water cooling with pre-defined cross-bow
Floatation annealing furnace and cooling equipment
The furnace and cooling technology is the heart of the process. The strip enters a floatation furnace where it is guided sinusoidal in a contactless floating mode. It is heated up and kept at the required strip temperatures in time, so the aluminum-alloy obtains their structure. Especially 2xxx and 7xxx aerospace alloys require highcooling rates of some 400 kelvin per second. For 6xxx automotive alloys mostly moderate but flexible cooling rates between 25 and 100 kelvin per second are necessary. The cooling process is executed as a combination of water and air cooling. A mathematical model calculates the necessary settings for the annealing and cooling process under consideration of the mechanical properties.
After the furnace, some alloys pass through a tension leveler to improve the required strip flatness. Depending on the material requirements the machine is able to operate without switching the leveling cartridge in either stretch bending or pure stretch mode. The settings are specified by a physical process model. In the following spray cleaning process the remaining surface impurities will be removed and the strip surface will be activated. Here special nozzles are used to avoid clogging and the nozzle bars are switchable for higher process flexibility.
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High-performance floatation furnace for aluminum automotive qualities. -
Chemical treatment
Coating technologies geared to your requirements
After annealing and cooling, a chemical coating is precisely applied onto the strip surface by a vertical or horizontal roll coater. The strip is coated evenly on each side with predefined surface thicknesses. Alternatively, a spray passivation can be used instead of roll coating. Passivation creates a uniform and dense layer of aluminum oxide on the surface (sealing layer). This layer serves several purposes: It improves the corrosion protection of the strips and thus protects them from undesirable corrosion.
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ChemCoater for heat treatment of aluminum strip -
Cleaning technology
Cleaning and de-oxidation
We design all our cleaning components to ensure excellent surface quality at minimum media consumption. You'll find a wealth of experience in our cleaning sections, so we can supply sophisticated components with a high level of automation. Normally, in our systems, the strip passes through spraying tanks made of stainless steel. Several nozzle tubes with clog-free, spoon-type nozzles in the closed tanks spray the cleaning medium onto both strip surfaces. It's easy to adjust the spray angle of the nozzles from the outside during the ongoing process.
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Cleaning technology for aluminum strip
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Tension leveler
Achieving optimal flatness and tension control
The SMS group tension leveler ensures precise flatness and tension control before strip cleaning and coating. The machine is made of a bending and correcting roller arrangement, along with at least one upstream and downstream bridle roll set to adjust the tension. Different leveling cartridges can be used as required for the material properties and dimensions. Leveling rolls and elongation settings are preset via level 2 automation, optimizing tension and bending. A closed-loop system maintains constant elongation across the strip length. Depending on the material requirements, the machine can be operated in two different modes: the pure stretch mode (without bending cassette) or in bending mode (with bending cassette).
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Tension leveling before cleaning and coating process to achieve flatness and tension control -
Flotation dryer and regenerative thermal oxidizer
Efficient thermal process technology for aluminum color coating lines
Efficient heating and cooling technology is a necessary pre-condition to produce high-quality aluminum strips successfully. SMS group offers efficient convection dryers for color coating lines. Optimized floatation nozzles ensure a contact-free strip travel through the whole thermal treatment section. The application of modern burner technology and control systems allows an efficient operation. The flue gases in the exhaust air of color coating lines are burned in an afterburning system (regenerative thermal oxidizer) and fed back into the process.
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The RTO burns the solvent containing exhaust air -
Coating technology
Precise and reliable coating
We offer a comprehensive range of coating systems for color coating lines. Whichever type you choose, you benefit from top precision and reliability. Just as dependable is our closed-loop thickness regulation system because it guarantees precise coat thickness every time.
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Color Coating
