Electrocoating

Electrocoating is a method of giving a metal an organic finish by using electrical current to deposit the paint. The process works on the simple principle of Opposites Attract.

Thus the fundamental principle of electrocoating is that materials with opposite electrical charges attract. An Electrocoat System applies a DC charge to a metal part immersed in a bath of oppositely charged paint particles. The paint particles are drawn to the metal part and paint is deposited on the part, forming an even, continuous film over every surface, in every crevice and corner, until the coating reaches the desired thickness. At that thickness, the film insulates the part and the attraction of paint particle stops and electrocoating is complete.

Electrocoating could be protective, decorative and may combine the properties of both depending upon the end use

Types of

Electrocoat

Depending upon the polarity of the charge, electrocoating is classified as either:

• Anodic, or
• Cathodic

ANODIC: In Anodic Electrocoating, the part to be coated is the anode with a positive electrical charge which attracts negatively charged paint particles in paint bath. In the anodic process, small amounts of metal ions migrate into the paint film, which limit the performance properties of these systems. Their main use is for products in interior or moderately aggressive exterior environments. Anodic coatings are economical and offers excellent color and gloss control.

CATHODIC: The cathodic process is just the opposite of anodic process. In Cathodic Electrocoating, the part to be coated is given a negative charge, attracting the positively charged paint particle. The reversing of anodic polarities greatly reduces the amount of ions entering the cured paint film and thus enhances the properties of cathodic electrocoated products. Cathodic electrocoating are high performance coatings with excellent corrosion resistance and can withstand the harshness of exterior environment.

The Process

The Electrocoat Process can be divided into the following four distinct sections:

• Pretreatment
• Electrocoat Bath and Ancillary Equipment
• Post Rinses
• Bake Oven