When an automobile body that is composed of press-molded or welded steel plates and aluminum is coated and parts like engines or tires are assembled, it becomes an automobile which we are accustomed to seeing everywhere. Of these processes, coating is effective for protecting the surface of an automobile body and making the automobile body look beautiful. A coating film formed by coating is usually consists of three to five layers.
Removing iron powders and oils adhering to materials such as steel plate enhances adhesion to electro-deposition coatings. It also forms a chemical coating film and increases the resistance to corrosion, using chemical reactions. | ||
Automobile bodies are dipped in a large vessel containing electro-deposition coatings for preventing rust, and coated by applying electrical current. This makes it possible to coat the inside of the automobile body which is difficult to coat by spray-coating. | ||
This is done by making the automobile body look beautiful and reducing the damage due to chipping. | ||
In the top coating, the final coating process, after having undercoated for coloring, a clear coat is coated to make the surface glossy and improve weatherproofing. |
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Metal parts which are heavily used in automobiles require high corrosion resistance, thus high rust-preventive electro-deposition coatings are used. Of these parts, frames for trucks and other associated parts that are exposed to sunshine or rain are treated with electro-deposition coatings which additionally have weather-proofing properties. These steel plate parts are basically finished with a single film of electro-deposition coating to become a final product.
Many plastic parts are also used in cars. Of these parts, bumpers are made of polypropylene for absorbing anti-personnel impact and weight-saving. Polypropylene generally rejects coatings, so special primer coatings* are used.
*Primer coating: A coating that is directly coated on material.
This type of coating is specifically used for automobile parts whose material is thick like cast metal and difficult to cure by heating.