Knowledge of Electropolishing Processes

Features of the electropolishing process

Electropolishing processes have high efficiency and the metal part which is processed by the electropolishing process has good quality. High gloss can be obtained by the electropolishing process within a few minutes. Pressure regulators, rectifiers, electrolytic tanks and other devices are required for the electropolishing process.

 

The technological process of the electropolishing process

Chemical degreasing → hot water washing → cold water washing → electropolishing → hot water washing → cold water washing → passivation → cold water washing → hot water washing → hot pure water washing 

Note: Adjust some of the processes according to the actual situation.

 

Advantages and disadvantages of the electropolishing process

Advantages

1. Metal parts which are processed by electropolishing processes have the same color on inner and outer surfaces; the metal parts have lasting gloss and their concave part which can not be totally processed by mechanical polishing can be leveled.

2. The electropolishing process has high production efficiency and low costs.

3. The electropolishing process improves corrosion resistance of the workpiece’s surface, and it can be applicable to all stainless steel parts.

 

Disadvantages

1. Quality of electropolishing is related to electrolytes and standards of current and voltage. You need to grope for different polishing parameters. However, there are a lot of parameters which can affect electropolishing, and it’s not easy to find the correct parameters for electropolishing.

2. It is difficult to get good results for samples such as cast iron and inclusions.

3. The composition of electrolytes is complex, and you need pay attention to safe operation.

 

Common problems

1. Why are spots or patches found on surfaces of metal parts after the electropolishing process?

Analysis of causes: Degreasing is not complete and there are still grease spots on the surface of the metal part before it is polished.
 

2. Why are gray and black patches on the partial surface of the metal part after it is processed by the electropolishing process?

Analysis of causes: The oxide skin is probably not completely removed. There are still some oxide skins. 

Solutions: Products such as stainless steel oxide skin removal solutions and stainless steel oxide skin removal creams can be used for removing oxide skins.

 

3. Why over corrosion occurs on edges and points of the workpiece?

Analysis of causes: Edges and points of the workpiece have excessive currents; temperature of electrolytes is too high and polishing time is too long. All of these will result in excessive dissolution.

Solutions: Adjust current density or solution temperature, or shorten the time. Check the electrode position and set a shield for the edge part.

 

4. Why is the surface of the workpiece not bright but gray?

Analysis of causes: The electropolishing solution may have no effect, or the effect is not obvious.

Solutions: Check whether or not the electrolytic polishing liquid is used for too long, quality of the solution becomes poor, the proportion of the solution is unbalanced.