CED Painting Plant

Four primary phases make up the entire process: pre-treating, electrocoating, rinsing, and baking. The type of electrocoating procedure can be either cathodic or anodic, contingent upon the substrate’s applied charge. The resulting coating has different qualities even if the methods are almost the same. Anodic methods coat positively charged substrates with paint; they were the first to be utilized in electrocoating. The pigment and resin particles that are negatively charged adhere to the substrate (anode). The dissolution and incorporation of substrate metals into the coating, which modifies surface characteristics, is one drawback of this technique. Compared to anodic electrocoating, cathodic electrocoating has many advantages and deposits paint onto negatively charged substrates. Cathodic electrocoating, for instance, can deposit over impurities, increase corrosion resistance, and produce a better color consistency over welded areas—all of which prevent metal dissolution of the substrate.

CED Process:
The electrocoat process can be divided into four distinct steps:
1. Pretreatment
2. CED/Electrocoat Bath
3. Post Rinses
4. Baking
Pretreatment – cleaning and phosphating the metal
The metal is cleaned and phosphated in the pretreatment zone in order to get it ready for electrocoating. To meet the performance standards that today’s product end user wants, the product must be cleaned and phosphated. When coating steel and iron components, a premium zinc phosphate system applied by immersion technique is usually utilized.
CED/Electrocoat Bath – applying coating in bath
The electrocoat bath and ancillary equipment zone is where the coating is applied and the process control equipment operates. The electrocoat bath consists of 80-90% deionized water and 10-20% paint solids. The deionized water acts as the carrier for the paint solids which are under constant agitation. The solids consist of resin and pigment. Resin is the backbone of the final paint film and provides corrosion protection, durability and toughness. Pigments are used to provide color and gloss.
Post Rinses – rinsing off excess paint solids
The post rinses provide both quality and conservation. During the electrocoat process, paint is applied to a part at a certain film thickness, regulated by the amount of voltage applied. Once the coating reaches the desired film thickness, the part insulates and the coating process slows down. As the part exits the bath, paint solids cling to the surface and have to be rinsed off to maintain efficiency and aesthetics. The excess paint solids are called “drag out” or “cream coat.” These excess paint solids are returned to the tank to create a coating application efficiency above 95%.
Baking Oven – thermally curing the paint film
The bake oven receives the parts after they exit the post rinses. The bake oven cross links and cures the paint film to assure maximum performance properties. The minimum bake schedule is 20 minutes with the part temperature at 375°F for most electrocoat technologies. However, there is also a “low temperature cure” electrocoat material. This material has a minimum cure of 20 minutes at a part temperature of 180°F so that many assemblies containing seals, bushings, bearings, or oil can use the electrocoat process.
Why CED Based Coating: An object’s surface can be coated with CED coating, also known as cathodic electrodeposited coating. The maximum level of corrosion protection is provided by this electronically applied coating type. Because of its extreme durability, it is frequently used to coat car parts and components. However, in order for the metal surface to be painted correctly, it must first be prepared. This procedure is comparable to the “laying of foundation” procedure.

The requirement of pre-treatment before CED Coating on automobile products is due to the following:

• Cleaning of the surface for oil, physical contamination & rust
• Making such a surface condition that has higher degree of paint-adhesion
• Minimize or eliminate any chance of reaction of paint with the base metal
• Provide added benefit of high level of corrosion resistance
Benefits of CED Coating
• Highest level of rust resistance
• Allows coating of highly recessed areas
• Provide ability to coat complex shapes with unmatched preciseness
• Transfer efficiency of over 95%, reduced paint wastage
• CED paint does not sag during curing and doesn’t wash off in enclosed areas due to hot vapours.