High surface quality thanks to plasma polishing

Surface treatment using polishing is a known and widely applied technology, often used for creating reflective surfaces with an extremely low Ra value. Besides optical effects, among other things this good surface quality also influences the friction, corrosion resistance (above all with stainless steel), aesthetic qualities and resistance against biofilms forming. This is why it is important pieces can be polished in a cost-effective way.

The downside of classic polishing is that the geometry is heavily restricted and the process is time-consuming. Polishing large pieces, such as moulds, is labour intensive and the quality is all down to the professional’s skill. A technology recently gaining attention and able to offer a good alternative is plasma polishing. The workpiece is immersed in an electrolyte, after which a voltage is applied between it and the bath. Once a critical current density has been reached, a gas layer will arise around the anode (the workpiece), filled with plasma. Electrical discharges take place in this gas cloud, which create a polish effect on the surface of the workpiece.

Principle of plasma polishing

The advantage of this technology is that the process allows roughness up to 0.05 µm Ra, with extremely short process times (only a few minutes) and a high dimensional accuracy. A non-acidic electrolyte is now being used, meaning the impact on the environment is also smaller. The features of the process mean plasma polishing is particularly suitable for treating entire components and series, and is less suitable for applications such as moulds, where only certain areas require polish quality.

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(photo above : polished metal surface)