What are the types of anodizing for aluminum

XingLi achieves the best anodizing results with Cyklos

The rotation process patented by Schmid for anodizing aluminum meets the strict requirements of the automotive industry at XingLi without the usual post-processing. This makes Cyklos a decisive competitive advantage for the Chinese anodizer.

Colorful carabiners, high-precision injection nozzles, elegant packaging made of aluminum - the possible areas of application for chemical surface finishing are diverse. In the conventional processes of chemical surface treatment, the parts are treated by immersion in a mostly aqueous solution. The layer thickness can vary and, due to gas bubbles when immersed, scooping parts that have partially enclosed cavities can have poor coating results. The situation is different with Cyklos von Schmid: Thanks to the patented rotation process, there is better convection (flow movement) in the process solutions, so that the gas bubbles are released from the cavities and the surface treatment is optimized.

KunShanshi XingLi Automotive Parts Co. Ltd, which specializes in chemical aluminum processing, has been producing aluminum hydraulic valve blocks with Cyklos for a year. The component controls the shifting processes of an automatic transmission. The tribological requirements are correspondingly high. So that no hysteresis occurs, the uniformity of the oxide layer, the accuracy of fit and the surface roughness must be met exactly.

XingLi's customer, one of the world's most renowned automotive suppliers, regularly carries out hydraulic tests on a test bench specially developed for this component. In order for the components to pass the test, the surface roughness may change by a maximum of Ra 0.3 µm as a result of anodizing. With the conventional, static immersion process, the Delta Ra is about twice as high, so that the parts have to be mechanically reworked. Since XingLi, which employs 30 people in Kunshan (China), has been using Cyklos to anodize the cast aluminum blocks, the post-processing step for surface smoothing has been omitted. A significant competitive advantage.

Patented rotation process

Due to the rotation process, Cyklos achieves excellent surface quality. In contrast to the immersion process, the 360 ​​° rotation detaches all of the gas bubbles from the workpiece and especially from the cavities. This means that the process can take place uniformly everywhere. The process technology is similar to that of molded part etching and circuit board processing - areas in which Schmid has been a technology leader for decades.

Like all Schmid wet systems, Cyklos has a modular structure and a high degree of automation. Thanks to the modularity, the system is precisely adapted to the needs of the user. In general, the system can be designed either for anodizing aluminum or titanium or for chemical deburring of steel parts.

Before machining, the workpieces are clamped on product-specific workpiece carriers for optimal contact. The format of the workpiece carrier corresponds to 450 mm x 330 mm, the maximum height approx. 200 mm. The subsequent process is fully automated. The workpiece carriers are pushed linearly into the following basin by a transport arm. A rotor system takes up to four workpiece carriers there and guides them through the process solution using the principle of rotation. The automation follows the principle of first in - first out, so that all workpieces go through exactly the same process. Depending on the geometry and size, a throughput of 0.5 to 50 million workpieces per year is possible.

Better working environment

With anodic oxidation, the aluminum part is connected in an electrolyte made from dilute sulfuric acid as an anode (positive pole) and aluminum oxide is formed on the surface of the workpiece through the electrochemical generation of oxygen. The system is completely enclosed and therefore does not emit any pollutants into the working environment. Since the system also works fully automatically - which reduces the intervention of the operating personnel to a minimum - Cyklos offers the employees the best possible protection.

The system also has an HMI-controlled process control. A data logging system is integrated in this for the monitoring and recording of all necessary process parameters. Industry 4.0 suitability enables traceability and ensures constant quality and reproducibility. Thanks to the precise control and regulation, the quality of the oxide layer to be produced can be directly influenced. Above all, the roughness and the uniformity of the layer can be checked here. In addition, the regulated dosage reduces the consumption of chemicals. The processing time depends on the desired layer thickness and the alloy and is around 10 µm to 60 µm per hour. Without anodizing, aluminum has a hardness of around 100 HV. Hard anodized surfaces reach up to 450 HV depending on the type of anodization, i.e. high wear resistance.

Technology center for machining trials

Schmid has installed a Cyklos system for chemical surface treatment in its Technology Center in Freudenstadt (Germany). The company, founded in 1864, uses it to carry out machining tests and samples. A feature that XingLi also used in the run-up to procurement. During the sampling, the qualitative expectations were even exceeded.

XingLi is extremely satisfied with the Cyklos and manufactures high quality products. Due to the increasing number of orders, the company is planning to expand the facility. Due to the typical modular structure, the capacity of the system can be increased by around 50% by upgrading. XingLi wants to grow further in the medium term. When the modern production hall was expanded, space was already provided for a second Cyklos.

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