Taking A Closer Look At The E-Coating Process

E-coating Process

In a recent newsletter article entitled The Industrial Uses of E-Coating , we covered the basics of electrophoretic painting, or e-coating. We discussed how it can be a highly effective solution for undercoating and other common painting or coating applications. This month, we’d like to take a closer look at the actual e-coating process and elaborate on the steps involved. While the procedure may vary somewhat depending on the application, an e-coating process typically entails the following:

  • Cleaning and pre-treating– It’s critical to clean the parts prior to e-coating, as this will remove the bulk of the oil, grease or other contaminants from the surface. The type of chemicals used for cleaning and pretreating can vary depending on the substrate, but immersion into a tank containing an inorganic phosphate solution is usually the preferred method with metal parts made of steel or iron.
  • Immersion into e-coating bath – Once the parts have been cleaned and pre-treated, they are ready for immersion into the e-coating bath, which may consist of a black epoxy paint and deionized water solution. (The typical ratio is 80-85% deionized water to 15-20% paint solid.) The total immersion of the substrate into the bath is what provides such a thorough interior and exterior coating of the part – it’s also what makes e-coating so effective. A DC electric current is then introduced to agitate the solution and deposit the coating onto the parts. The thickness of the deposited coating can vary depending on the amount of voltage applied, which generally ranges from 25 to 400V.
  • Rinsing– Once the coating reaches the desired thickness, it’s time to remove the parts from the bath. At this point, it is necessary to rinse the parts to remove the “cream coat,” which is the term used to describe the remaining paint solids that are still clinging to the surface of the parts. Failure to remove the cream coat will detract from the appearance of the coating. During rinsing, the excess solids are recovered and returned to the e-coat tank.
  • Baking– It’s critical to clean the parts prior to e-coating, as this will remove the bulk of the oil, grease or other contaminants from the surface. The type of chemicals used for cleaning and pretreating can vary depending on the substrate, but immersion into a tank containing an inorganic phosphate solution is usually the preferred method with metal parts made of steel or iron.
    However, part size, composition and paint chemistry are all key factors that must be taken into consideration when selecting the appropriate baking time and temperature. Many modern baking ovens offer a multi-stage curing process that can minimize water-spotting and enhance the flow of the film, which improves the appearance of the finished product.

Contact Sharretts Plating Company to learn more about the e-coating process and how it may be able to benefit your manufacturing applications.

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