What is E-Coating?
Electrophoretic deposition (e-coating) is a process that suspends particles in a liquid medium and applies a current, generating an electric field that deposits the particles on a metal substrate.
An electric current reduces dissolved metal cations to form a thin, coherent metal coating in electroplating. The process is comparable to electrophoretic deposition (e-coating/electric coating).
They apply an electric current while dipping parts in an epoxy, water-based solution, or paint bath to create an e-coating.
The current depositing forms a coating on the component, floating particles when the current is in the bath. After coating, the part spends time in a curing oven.
2 Common E-Coating Processes
Anionic and cationic are the most common e-coating processes.
An anionic process charges the metal components using a negatively charged bath solution. Anionic processes are common in the general metal industry because of their color control, ease of use, and affordability.
They used an anionic process coating on non-corrosive environment components more often than not.
The cationic process provides a more corrosion-resistant surface and is the reverse of the anionic process. The material is negatively charged, and the fluid is positively charged. The chemistry behind the cationic process is based on acrylics or epoxies. If corrosion protection is crucial, use epoxy compositions. If color retention or longevity is crucial, use acrylics.
E-Coat Evolution
With a history dating back to the 1930s, e-coating provided a coating inside steel food containers. Around 30 years later, many industrial applications started using the e-coating system.
Ford Motor Company was at the forefront of e-coating technology. In the early 1960s, Ford scientists created an anodic process for e-coating an assembled auto giving anti-corrosion protection. A few years later, domestic appliances and architectural aluminum successfully used the e-coating system.
In the mid-1970s, Ford advanced e-coat technology by replacing anodic with cathodic processes where a continual DC circuit in the bath applies the e-coatings.
Since then, recent advancements in e-coating technology have led to improved edge protection, low-voltage organic compounds, and more protection from UV light. E-coating is now used when making electrical components and heavy equipment needing corrosion protection.
TYPICAL E-COAT PROCESS
There are four main parts to the e-coating process:
- Cleaning and pre-treating the component: a phosphate is applied to the surface of the component, preparing the piece for e-coating
- Immersing the component into a bath containing direct current and applying the coating to the part’s surface
- A complete rinse
- Baking the part for at least 20 minutes while the component is around 375 ºF
E-Coat Advantages
Rather than discussing the pros and cons of powder coating versus e-coating, we’ll only discuss the benefits of employing the e-coat procedure in this article.
E-coating provides the following advantages:
- A greater coverage when a component is e-coated. Total immersion covers all the hard-to-reach places.
- More thickness control using varying levels of DC.
- A reduction of rework, paint usage, and VOC emission