Plating

 Plating is a surface covering in which a metal is deposited on a conductive surface. Plating has been done for hundreds of years; it is also critical for modern technology. Plating is used to decorate objects, for corrosion inhibition, to improve solderability, to harden, to improve wearability, to reduce friction, to improve paint adhesion, to alter conductivity, to improve IR reflectivity, for radiation shielding, and for other purposes. Jewelry typically uses plating to give a silver or gold finish. Thin-film deposition has plated objects as small as an atom; therefore, plating finds uses in nanotechnology.
 
There are several plating methods, and many variations. In one method, a solid surface is covered with a metal sheet, and then heat and pressure are applied to fuse them (a version of this is Sheffield plate). Other plating techniques include vapor deposition under vacuum and sputter deposition. Recently, plating often refers to using liquids. Metallizing refers to coating metal on non-metallic objects.


From wikipedia
  Plating Applications
 
Electroplating is used for:
•appearance or for decoration
•protection
•special surface properties
•engineering or mechanical properties
 
Electroplating is widely used in various industries for coating metal objects with a thin layer of a different metal. The layer of metal deposited has some desired property, which the metal of the object lacks. For example, chromium plating is done on many objects such as car parts, bath taps, kitchen gas burners, wheel rims and many others that chromium is very corrosion resistant, and thus prolongs the life of the parts. Electroplating has wide usage in industries. It is also used in making inexpensive jewelry. Electroplating increases life of metal and prevents corrosion. Zinc, chrome and nickel are the most common industrial plating metals.
 
Plating Methods
 

• Rack Plating Method

Rack plating is the most commonly used method where the metal to be plated is hung on a frame or rack.
 

• Barrel Plating

Barrel plating occurs in a closed barrel. The process is used when electroplating smaller parts or there is a lower level of processing requirements/standards.
 

• Manual Plating

In manual metal plating everything is performed by a trained technician. It is for small batch plating.
 
Typical Steps in Electroplating Process

This is the process for plating steel aerospace parts with cadmium.
 
Step 1 Cleaning: surface must be free of contaminants for bonding to take place.
Step 2: Rinsing and dry (if needed)
Step 3: Acid cleaning and etching: Sand blasting with aluminum oxide will roughen up the surface so that the plating metal adheres better.
Step 4. Rinsing (if needed)
Step 5. Conversion Coating or Plating
Step 6: Water Rinsing (1 minute)
Step 7: Chemical Rinsing to make parts more rust resistant
Step 8: Rinse in Hot Water