Karl Trautz, HEMO GmbH, Ötisheim, Germany
It is well known that high-tech coating processes require significantly higher component cleanliness compared to conventional coating methods. A wide variety of, sometimes unknown, contaminants must be reliably and reproducibly removed. The search for an optimal cleaning process, especially regarding the increasingly important cost-benefit ratio (unit costs), presents a major challenge.
In this context, it is interesting to consider the still underrepresented use of modern organic solvents in combination with aqueous cleaning media.
Here, the important principle of cleaning technology, "like dissolves like", must be taken into account. This principle means that hydrophilic contaminants should preferably be removed with aqueous media, and lipophilic contaminants with organic solvents such as modified alcohols or isoparaffins.
Often, there are very diverse contaminants from both groups, and additionally, of course, non-soluble contaminants such as metallic or mineral particles. In this case, hybrid cleaning processes, such as the Hybrid or Beyond process from HEMO, become interesting and advantageous.
In the Hybrid process, organic solvents such as isoparaffins (hydrocarbons with chain lengths C9 to C14) or modified alcohols are first used in the same working chamber to remove lipophilic contaminants, followed by aqueous media with detergents to remove hydrophilic contaminants. After the aqueous stage, a final solvent stage is performed before the final drying.
It is important to recognize the enormous advantages of the overall process, which takes place in one working chamber or cleaning system in sequence, compared to carrying out the treatment steps in several separate cleaning systems. This relates, for example, to issues such as the prevention of corrosion or the perfection of part drying.
HEMO already offers the market many proven processes.