Plant manufacturers are confronted with the end of the combustion engine. Hardly any new production lines are being planned and the few remaining projects are fiercely contested. This is also evident in parts cleaning, as its systems were and are an integral part of such production lines. However, instead of cylinder heads, sustainable mobility and the economy are now on the development agenda. The family-owned company Meißner Technik Müllenbach GmbH from Marienheide has been working on patented system technology for parts cleaning in the field of combustion engines - and has used, adapted and further developed existing concepts.
Development markets are the ramp-up of the hydrogen economy and electromobility. The electrode surfaces of electrolysers in particular require ultra-clean surfaces. This is where cleaning technology can develop in new ways. Another rapidly growing area is electromobility. Battery trays made of aluminum are used there on a large scale. During production, forming and machining processes occur that leave behind machining fluids and metal residues.
As the example of battery trays shows, aluminum components are particularly popular in electromobility. They have a low mass and high strength. This makes them particularly interesting for vehicle construction, as their installation can reduce the overall weight of the vehicle. Aluminum parts are often bonded and are therefore now coated with titanium oxide. Aluminum is a base metal that forms an undefined oxide layer when exposed to air. This is responsible for the appearance of the surface. However, this oxide layer dissolves in acids and alkalis, revealing the bare metal. The oxide layer that forms in the air interferes with the bonding of aluminum parts due to its undefined structure. Therefore, a pre-treatment is necessary in which the oxide is removed and the surface is then coated with titanium oxide. The titanium oxide layer has a thickness of around 30 µm. Due to its defined structure, the layer is also suitable for bonding.
Digital visualization of the system technology
In the classic process, the components are passed through treatment baths in a step-by-step process. First, the oxide layer is removed in a strongly alkaline bath. The classic process sequence then includes two rinsing processes. The next step involves coating with titanium oxide in strongly acidic media. This process has to contend with carry-over problems, as caustic soda quickly accumulates in the two rinsing processes. This requires efficient process engineering, which is provided by Meißner Technik Müllenbach GmbH.
In the alternative, patented process, the parts to be coated are moved through the treatment basins in baskets using a robot. The robot enables much greater flexibility in the process sequence. According to this, the coating with the titanium electrolyte in the first tank is followed by post-treatment. After a highly acidic treatment, the parts are then transferred to an alkaline rinsing environment using a robot. This leads to acid-alkali neutralization in the rinsing stages. This neutralization process considerably extends the service life of the rinse and the titanium oxide coating solution and thus optimally prepares the coating by changing the composition of the rinse bath. The decisive difference here is the use of robots.
Stacking systems in front of the system ensure a smooth throughput. Sophisticated automation is part of the system technology
In addition to the increased flexibility, another advantage of the robot is that it can transport the components like a hand. This makes it easier for the applied liquids to run off, as the robot holds the components at an angle to the surface of the bath. The liquid level in the baths is also regulated. This bath guidance also helps to extend the service life. The dip tanks remove oil and floating particles from their surfaces by means of efficient bath level cleaning. This prevents problems caused by floating oil lyes on the bath surface and therefore also on the parts coated with titanium oxide - a significant improvement for the coating process.
The process-relevant dip tanks are fed from separate storage tanks. The medium flows through a filter during activation. This also leads to longer bath service lives with stable process results. The process runs largely at room temperature. Only the rinsing and degreasing baths are heated before drying. This transfers thermal energy to the component, and the energy stored in the component ensures an efficient drying process. To dry, the medium must be transferred from the liquid to the gaseous phase. If part of this drying energy is already provided by the component, the process is more energy-efficient than if only hot air is responsible for transporting the energy. In the patented process, the waste heat from the system processes is used to heat the hot baths via heat pumps.
The process from Meißner Technik Müllenbach GmbH aims to achieve greater sustainability. One result is significantly reduced operating costs thanks to the economical use of energy and coating chemicals. Sophisticated process engineering can therefore be a building block in mastering the major challenges of the transformation.
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