Electroplating is the process of applying one or more layers of a metal to a part.
The process used in electroplating is called electrodeposition. It is analogous to a galvanic cell acting in reverse. The part to be plated is the cathode of the circuit. In one technique, the anode is made of the metal to be plated on the part.
Both components are immersed in a solution called an electrolyte containing one or more dissolved metal salts as well as other ions that permit the flow of electricity.
A power supply supplies a direct current to the anode, oxidizing the metal atoms that comprise it and allowing them to dissolve in the solution.
At the cathode, the dissolved metal ions in the electrolyte solution are reduced at the interface between the solution and the cathode, such that they "plate out" onto the cathode.
The rate at which the anode is dissolved is equal to the rate at which the cathode is plated, vis-a-vis the current flowing through the circuit. In this manner, the ions in the electrolyte bath are continuously replenished by the anode by passing a positively charged electrical current through a solution containing dissolved metal ions (anode) and a negatively charged electrical current through your part to be plated (cathode).
The history dates back to the ancient Egyptians who would coat metals and non-metals with gold or a process known as “gilding”,?the first known surface finish.
Some metals apply more evenly than others, but the use of electricity means that the metal being deposited flows more easily to high current areas or the edges of a part.
This tendency is especially pronounced on complex shapes or when trying to plate the inside or ID portion of a part. In addition to just single metals being applied, it is possible to simultaneously plate alloys of materials such as Tin and Lead or Zinc and Iron to achieve desired customized properties.