Common problems in stainless steel electrolytic polishing

Why are there seemingly unpolished spots or small pieces on the surface after electropolishing?
Reason analysis: Before polishing, the oil removal was not thorough, and there were still oil stains on the surface.
Solution: Use "Taoyuan High Efficiency Degreasing Agent" or "Taoyuan High Quality Dewaxing Water" to soak at 60-90 ℃ for 5-20 minutes. The cleaning effect is better when using Super Zhibo. After prolonged use, it is necessary to add or replace the cleaning agent
Why are there gray black patches on the surface after polishing?
Cause analysis: It is possible that the oxide skin has not been thoroughly removed. Oxidized skin still exists locally.
Solution: Increase the intensity of removing oxide skin, and choose products such as "stainless steel oxide skin removal solution" and "stainless steel oxide skin removal paste". Due to the abundance of rust and oxide skin removal products, specific applicable products can be consulted.
3. What is the cause of excessive corrosion at the edges and tips of the workpiece after polishing?
Cause analysis: Excessive current at edges and tips, or high electrolyte temperature and polishing time, resulting in excessive dissolution.
Solution: Adjust the current density or solution temperature, or shorten the time. Check the position of the electrodes and set shielding at the edges and corners.
4. Why is the workpiece not bright and appears gray and dark after polishing?
Analysis reason: Perhaps the electrochemical polishing solution is no longer effective or the effect is not obvious.
Solution: Check if the electrolytic polishing solution has been used for too long, the quality has decreased, or the proportion of solution components is out of balance.
What is the reason for white stripes on the surface of the workpiece after polishing?
Reason analysis: The relative density of the solution is too high, the liquid is too thick, and the relative density is greater than 1.62
Solution: Increase the stirring degree of the solution. If the relative density of the solution is too high, dilute it with water to 1.52. Heat at 90~100 ℃ for one hour.
6. Why are there negative and positive surfaces on the polished surface, as well as local lack of luster?
Reason analysis: The position where the workpiece is placed is not aligned with the cathode, or the workpiece is shielded from each other.
Solution: Adjust the workpiece appropriately to ensure the appropriate position between the workpiece and the cathode, and ensure a reasonable distribution of power.
7. After polishing, the surface of the workpiece is flat and smooth, but some points or blocks are not bright enough, or there are vertical dark stripes. What is the general reason for this?
Reason analysis: It may be that the bubbles generated on the surface of the workpiece during the later polishing stage did not detach and adhere to the surface in a timely manner, or there were airflow lines on the surface.
Solution: Increase the current density to increase the amount of gas evolution for bubble desorption, or increase the stirring speed of the solution to increase the flow of the solution.
8. What is the reason why the contact points between the parts and the fixture are dull and have brown spots, and the rest of the surface is shiny?
Cause analysis: It may be due to poor contact between the parts and the fixture, resulting in uneven current distribution or insufficient contact points between the parts and the fixture.
Solution: Polish the contact points of the fixture to ensure good conductivity, or increase the contact area between the part and the fixture.
9. Some parts polished in the same groove are bright, some are not bright, or some parts are not bright.
Reason analysis: There are too many polished workpieces in the same slot, resulting in uneven current distribution or overlapping and shielding between workpieces.
Solution: Reduce the number of polished workpieces in the same slot, or pay attention to the placement of workpieces.
10. Why are there silver white spots near the concave part of the polished part and the contact point between the part and the hanger?
Reason analysis: It is possible that the concave part of the part is shielded by the part itself or the hanging tool.
Solution: Change the position of the parts appropriately so that the recessed parts can receive power lines, reduce the distance between electrodes, or increase current density.
11. We have strictly followed the process specifications for operation. Why is there more or less excessive corrosion on the surface of the polished parts?
Reason analysis: Is the solution temperature too high or the current density too high? If there are no problems with the solution preparation and strict operation, it may be a problem with the treatment before polishing.
Solution: Strictly implement the pre-treatment operation of electrochemical polishing to avoid excessive corrosion during the pickling process. Do not leave cleaning water on the surface of the parts and bring it into the polishing groove.
12. Stainless steel universal electrolyte "Why does foam appear after a period of use?
Reason analysis: The surface of the workpiece has not been degreased, and some oil stains are floating on the surface of the electrolyte, which brings difficulties to the operation.
Solution: If this situation has already occurred, it is recommended to remove the surface oil stains. If it does not occur, it is recommended to remove the oil before polishing.
13. What is the relationship between sulfuric acid and phosphoric acid in electrochemical polishing solution?
Reason analysis: Due to excessive sulfuric acid, the polishing speed is too fast, which can accelerate corrosion of the metal substrate. Due to excessive phosphoric acid, a type of mucous membrane can be adsorbed on the surface of the workpiece, resulting in a decrease in brightness and slower polishing speed. Of course, other factors cannot be ruled out.
Solution: Adjust the appropriate proportion of sulfuric acid and phosphoric acid. You can also choose the formula of "Taoyuan Various Chromium Free Electrolytic Additives".
14. After polishing, the surface of the workpiece lacks luster and there are white spots on a light yellow substrate. What is the general reason for this?
Reason analysis: It may be that the chromium anhydride content in the electrolytic polishing solution is too high, even exceeding 1.5%.
Solution: Chromium ions are heavy metal ions that have carcinogenic effects on the human body and pollute the environment. Therefore, chromium free polishing solution can be used. It is recommended to use "Taoyuan Stainless Steel Universal Electrolyte".
15. What are the main cost accounting methods for electrolytes?
Mainly including electricity bills, electrolytes, rectifiers, electrolytic cells, plates, copper rods, heating tubes, etc.
What is the current density of various stainless steel materials during electrolytic polishing? What is the correlation with the cost of electrolysis?
Reason analysis: Under normal market conditions, the density of various stainless steel materials in the electrolyte is: the current density of the 200 series stainless steel material is between 25-50 amperes, the current density of the 300 series stainless steel material is between 15-30 amperes, and the current density of the 400 series stainless steel material is between 30-55 amperes.
Solution: You can choose the "Stainless Steel Universal Electrolyte". The current density of the 200 series stainless steel material is between 15-25 amperes, the 300 series stainless steel material is between 10-15 amperes, and the 400 series stainless steel material is between 25-30 amperes. The higher the current density, the greater the power consumption. In the cost accounting of electrolysis, electricity accounts for a large proportion.
17. After polishing, wipe it clean and throw it away without luster. What is the reason for the light blue shadow?
Reason analysis: It may be that the electrochemical polishing solution was not heated or powered on after preparation, or the operating temperature of the solution was too low.
Solution: Heat the electric polishing solution at 120 ℃ for one hour or heat the electrolyte to the specified temperature.
18. What is the reason for the matte and yellow spots after polishing?
Reason analysis: It is possible that the relative density of the electrochemical solution is too low, which is less than 1.50.
Solution: Adjust the relative density of electric polishing or heat and concentrate at 80-100 ℃ to increase the relative density. Or replace with a new fluid.
Why do brown spots appear when the workpiece is removed from the groove after polishing?
Reason analysis: It may be due to insufficient electric polishing or a short time.
Solution: Firstly, extend the polishing time appropriately. If it is ineffective, it may be due to insufficient temperature or current density.
Why is it easy to experience sparking during electrolysis?
Reason analysis: There are three factors that lead to this phenomenon: first, the contact point between the fixture and the workpiece is not firm, second, the electrolyte density is too low, and third, the current density is too high.
Solution: Change multiple methods of connecting the fixture to the workpiece, and try to increase the contact points between the fixture and the workpiece as much as possible. If the electrolyte density is too low, the electrolyte can be replaced, and it is recommended to choose "stainless steel universal electrolyte".
What is the effect of operating temperature of stainless steel electrolyte on electrolytic polishing? What is the optimal temperature?
Reason analysis: Generally, the use temperature of electrolytes is between 50-90 ℃, with lower temperature, slower polishing speed, and decreased brightness. If the temperature is too high, the liquid will accelerate the corrosion of the workpiece, which can easily cause excessive corrosion of the workpiece, and the effective components of the electrolyte are easy to decompose.
Solution: When the temperature is low, it should be heated to the specified temperature. Various heating tubes (such as quartz or titanium material heating tubes) can be used for heating. The temperature will rise after long-term operation. When the temperature exceeds 90 ℃, the work should be stopped. Mixing or cooling circulation can be used for heat dissipation. The optimal usage temperature is 50-90 ℃, and the optimal usage temperature for "stainless steel universal electrolyte" is 50-80 ℃.
22. The surface of stainless steel workpieces is uneven and the pits are convex. What is the reason for this?
Reason analysis: There is a lot of surface corrosion, and the electrolyte only undergoes micro corrosion leveling. The more corroded electrolyte cannot be completely removed. If the polishing time is extended, a large amount of iron ions will sink into the bottom of the electrolyte, reducing its service life.
Solution: Clean the rust on the surface of the workpiece. It is recommended to use products such as "stainless steel activation solution", "rust removal water", and "oxide skin remover" for cleaning and rust removal.
23. What are the main factors that affect electrochemical polishing?
Temperature, time, workpiece material, electrolyte, voltage, current, and workpiece placement.
24. When performing stainless steel electrolytic polishing, a layer of light red substance is adsorbed on the surface, and there will be a short reaction time when the electrolyte is added again. What is the reason?
Reason analysis: With a copper hanging tool, copper ions enter the electrolyte and adsorb onto the anode surface, affecting the polishing quality. If they are placed again, there will be a short reaction time because the electrolyte dissolves the copper ions on the surface of the workpiece.
Solution: Use a titanium hanger, bake a film with polyvinyl chloride resin at the exposed area of the fixture, and scrape off the insulation film at the contact point to leak metal to facilitate conductivity.
25. What is the optimal area ratio for the anode and cathode?
The anode is between 1:2 and 3.5 compared to the cathode.
26. What is the optimal polar distance between the two poles?
The optimal distance between the cathode and the anode is 10-30 centimeters.
27. How to maintain stainless steel universal electrolytic polishing solution after aging?
After aging, sulfuric acid (density 1.78) can be added to the stainless steel universal electrolyte, with an amount of 5% by weight of the bath solution
28. When conducting electrolytic polishing for the first time, not only did it not emit brightness, but also all the surface of the workpiece turned black or gray. What is the reason for this?
Reason analysis: This phenomenon usually occurs when the two poles are connected in reverse. After the connection is reversed, the lead plate dissolves into the positive electrode, and the workpiece adsorbs onto the cathode. The iron, nickel, and chromium ions dissolved in the solution adsorb onto the surface of the workpiece, forming a film layer with poor adhesion.
Solution: Reconnect the positive and negative electrodes, connect the anode to the positive electrode, and connect the cathode to the negative electrode.