Metallic Coatings and Processes
Applying a metallic coating to a product serves a number of advantages, depending on its use. Electroplating has been used for decades in the jewelry and automotive industries. In this process, a metallic finish coating is attached to a metal product by means of an electric charge.
For example, a “gold plated” necklace is made of steel or other substance and electroplated with gold leaf. The resulting necklace is meant to look like a solid gold piece, but sold for a fraction of the cost. In the automotive field, it has been used to add sheen to trim pieces of the vehicle.
But an increasingly popular method of applying a metallic coating is through a process called physical vapor deposition or PVD. In this method, the product is placed in a vacuum at a very low temperature. The product is then saturated in the metal coating, providing a very thin, but very durable film.
It does not rely on an electrical charge to adhere to the product so a larger array of materials can be finished through the PVD method. Glass, plastic and other materials can be metallized. PVD technology has been refined greatly over the past three decades.
There are other reasons for applying a metallic coating besides aesthetics. Some of the advantages of a finished PVD coating include:
• Wear protection- in a product where corrosion is a concern, an inhibiting PVD coating can be applied. Tool, cutting dies, nuts and bolts are becoming popular items to apply a PVD coating;
• Vapor protection- the PVD coating can act as a vapor barrier, either to prevent the release of noxious product vapors or as a barrier to prevent moisture damage to the product;
• Friction reduction- In moving parts of machinery, certain PVD coatings can reduce the friction coefficient of two moving parts. The resulting friction protection can prolong the life of machinery, increase operating speeds and reduce heat build up.
Another advantage to a PVD applied coating is a uniform application, with a very thin final film. It is especially advantageous in products with grooves, corners and uneven surfaces. The PVD process doesn’t create a build up of coating. Finally, the PVD applied coating can be removed and reapplied a number of times over the life span of the coated product.
Because PVD coating remains a specialized field, company choices may be limited. It is usually best to choose a company that has experience in the field, with a solid track record of quality coatings.