The purpose of electrolytic polishing is to obtain a smoother and brighter surface effect, which is often used in the processing of aluminum alloy surface for smoothing and brightness requirements.Electrolytic polishing and mechanical polishing are the same, but they are very different in principle.When mechanical polishing, due to pressure and local high temperature, it will form a layer of amorphous surface on the polished surface.While electrolytic polishing has a selective dissolution, the principle of smoothing in electrolytic polishing is that the workpiece is realized by the difference of the dissolution rate of the microconcave surface in the electrolyte.Metal concave points and prominent in the anolyte with different concentration gradient, the concentration gradient has a great influence on the membrane layer of dissolved, and the concentration gradient is accomplished by using a high concentration of the electrolyte.During electrolysis, highlight points with larger current density, can accelerate the dissolution rate, and concave point, on the other hand, a relatively small current density, the dissolution rate is relatively slow, thus in the aluminum alloy surface smooth and bright effect.
There are two types of electrolytic polishing: first, the electrolytic polishing can completely replace the mechanical polishing, and the electrolytic polishing can obtain a smooth and shiny surface effect, but it is difficult to achieve the mirror effect.2 it is used for mechanical polishing precision polishing, after then depends on the quality of mechanical polishing, excellent mechanical polishing quality combining electrolytic polishing mirror polishing effect can be obtained, which is electrolytic polishing is the most typical USES in the aluminum alloy surface treatment.
In the case of the temperature electrolytic polishing of current density on the quality of the polishing and polishing time, current density within the limit of the workpiece surface bubbles generates at least, polishing time depending on the current density, temperature and aluminum alloy material, polishing commonly 3 ~ 15 min.
The polished surface will have a thin layer of oxide film, which needs to be removed before further processing. The removal method can be made by phosphoric acid method or other methods.
