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Refined with electricity: galvanisation

Overflowing with power

Galvanization enables functional coatings

Everyone comes into contact with electroplated objects without noticing it. From frames for glasses, plug connectors in coffee machines to chrome-plated taps on washbasins and galvanized components in the car. Using this technology, tools and scissors, for example, are nickel-plated to protect them against rust.

Electroplating involves refining metal objects by applying a thin layer of a different metal to them by using electricity. Electroplating technology enables functional coatings to be applied with a thickness of just a few micrometres and thus to use raw materials very specifically and efficiently.

How does electroplating technology work?

Firstly, a workpiece is immersed in a bath consisting of a metal salt solution (electrolyte) and connected to the negative electrode of a direct current source (cathode). The metal that is going to be deposited (e.g. nickel) is also placed in the bath and connected to the positive electrode of the direct current source (anode). The electric current dissolves the metal on the positive terminal, which is thus turned into metal ions. These metal ions are attracted by the workpiece on the negative terminal, where they are deposited as a thin metal coat.

The object being treated is coated evenly on all sides with gold, nickel, silver, copper or another metal. The longer the object is kept in the bath and the higher the electric current, the thicker the layer of metal will be.

Immersing and pickling in the Festo plants

Festo, too, uses this method during production. The component parts – for example, valve and cylinder housings – are given the necessary characteristics, such as chemical resistance, hardness, gloss or rust protection, in galvanic baths using electrolytic processes. The washed and degreased aluminium parts from the machining department are firstly pickled, when a layer of about ten micrometres – which equates to around 0.01 millimetres – is removed. In the anodizing process, they are finally given a 20 micrometres-thick coating which protects them from corrosion and ensures a low-friction surface.

When planning the electroplating process at the Scharnhausen Technology Plant, much attention was paid to energy efficiency. Several components can thus be anodised simultaneously in one tank and no retooling is necessary to change the anodizing substances. A heat exchanger enables energy to be recovered from the ventilation system.

Overview