Category Archives: electropolishing

Electropolishing Process

Depending on the industry standard you are working with, your electropolishing process can differ in a few ways. Make sure to consult with the ASTM standards for your industry or regulatory group. Below we will identify a typical electropolishing process including the pre-electropolishing and post-electropolishing methods for the perfect surface finish.

Pre-Electropolishing

It is important that all surfaces be uniformly exposed to the electrolyte solution so a pre-electropolishing wash process should be established. Classic Electropolishing puts all parts through a wash and rinse cycle with agitation to get any surface imperfections such as coolant or grease off of the parts. 

Carefully inspect your welds to ensure that the part has continuous seams and is free of pits or gaps where the electrolyte solution could collect.

Electropolishing

The electropolishing steps are discussed in additional posts on this blog. Recently we discussed the steps of DIY Electropolishing. DIY Electropolishing.

The basic steps of electropolishing include: heating the electrolytic solution, securing your work piece to the electropolishing tooling, submerging your work piece into the electrolytic solution, turning on the proper amps of electricity to begin the actual electropolishing.

  1. Heat the electrolytic solution securing your work piece to the electropolishing tooling, submerging your work piece into the electrolytic solution, turning on the proper amps of electricity to begin the actual electropolishing.
  2. Secure your work piece to the electropolishing tooling submerging your work piece into the electrolytic solution, turning on the proper amps of electricity to begin the actual electropolishing.
  3. Submerging your work piece into the electrolytic solution turning on the proper amps of electricity to begin the actual electropolishing.
  4. Turning on the proper amps of electricity to begin the actual electropolishing
  5. Set your timer to when the workpiece will be done electropolishing.
  6. Pull your workpiece out of the electrolyte solution and begin the post electropolishing process
  7. Neutralize your parts
  8. Rinse

Depending on the design specifications of your electropolishing process, you may need to electropolish the product, re-rack the product and then electropolish again so as to make sure that the entire workpiece is electropolished otherwise you might get extensive marks where the workpiece was being held in the rack tooling.

Post-Electropolishing

Following electropolishing all traces of the electrolyte solution are to be thoroughly removed from the part. One process to use after the part has been electropolished is a nitric acid followed by a hot rinse, followed by a rinse, followed by drying. According to ASTM B912 the electropolisher must include post-coating procedures as part of the process, as well as performance testing by means such as a salt spray test, a humidity test or a copper sulfate test. Surfaces should be dried with a soft, non-particulating cloth.

The preceding was meant to serve as an introductory blog post describing the steps of a typical electropolishing process. We have seen many different types of electropolishing processes. If you have variant processes or process improvements we would love to hear about them.

Citric Passivation vs. Nitric Passivation

We get many requests for both citric passivation and nitric passivation so we wanted to dispel the myths and help with your next project. Passivation is the act of becoming passive, that is, being less affected by environmental factors such as air and water. Most finishers will push you towards citric passivation and here is why. 

The benefits of citric passivation are both economical and environmental. Citric passivation is the more environmentally conscious choice. Nitric passivation solutions emit toxic gasses and must be handled and disposed of properly to avoid any environmental affects. Citric passivation solutions can be easily disposed of.

Citric passivation is more affordable. The citric passivation process takes less time overall. Combine this with the handling costs and the fact that less citric solution is needed with the process and you can get large pricing discounts by going with citric passivation.

Many of our customers also need help differentiating electropolishing and passivation so we made a little guide electropolishing vs. passivation. Let us quote out your next metal finishing project.

 

Foil Electropolishing

Many electropolishing companies boast their ability to do large products. At classic electropolishing, we go in the other direction. We are able to do commercial thin foil electropolishing for small medical components and components for electron microscopy. The foils we have worked generally have had a width of 200 μm to 400 μm but we are always open to testing out new products and processes.  

Electropolishing Clamp Marks

If you are a medical product designer, you may not have thought about how to specify  the electropolishing clamp positioning. Depending on the critical features of your product this can make a large difference.  Electropolishing requires the product to be touching an electrode which sends a current through the product. Depending on where the clamp is located, there may be slightly more material taken off of the product. Next time you are working out your drawing, make sure to identify where you would like the product clamped for electropolishing!

Don’t hesitate to contact Classic Electropolishing for your next project.