CHEMICAL PRE-TREATMENT
PICKLING
The term "pickling" describes the removal of rust, scales and oxide layers from component parts.
When is it necessary to pickle?
Rust, scales or oxide layers impede bonding underneath surface layers. For further processing such residues must be removed safely. This may be done with the help of radiation, but there are component parts, which may not be blasted for technical or economic reasons. In this case pickling is one option.
Why do rust or scales get to surfaces ?
Rust is the result of oxidation of iron exposed to aerial oxygen. Thereby the uppermost layer of iron converts to iron oxide under volume expansion. Similarly, this process happens with other metals. Each point of oxidation is the trigger point for further oxidation so that before further processing each and every area of oxidation must be removed.
Scales are also a kind of oxidation and result from exterior influences from the exterior onto the work pieces. Scales develop in the course of rolling, welding at the edges of the welding seam or in the course of cutting of sheet metals with a laser. Scales must also be removed.
Which ways of pickling are there?
We are not aware of any spray pickling method, which would be active enough to remove rust and scales safely. As pickling solutions are very aggressive the industrial systems used would be very badly affected by splashing.
We use immersion-pickling solutions. To this end our equipment disposes of two pickling baths, which may be used alternatively. The average pickling time for steel is roughly 10 minutes, for aluminium it is roughly 3 minutes. After the pickling process the component parts must be rinsed in a cascading triple sink so that oxidation cannot begin immediately again.
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zinc phosphating
chromalising
degreasing
CHEMICAL PRE-TREATMENT
