Why Auxiliary Anodes are Used in the Electroplating Process?

Why Auxiliary Anodes are Used in the Electroplating Process?

It is difficult to obtain a coating having a uniform thickness in the electroplating industry. The problem of non-uniformity in coating thickness is especially apparent when the object being coated has recessed areas. These recessed areas receive less current and, therefore, obtain a lesser deposit of metal from the plating solution.

Each plating solution has its peculiarities in the degree, the irregularity of the surface of the object being coated will affect the uniformity of the coating. It may be defined in terms of throwing power.

Throwing power refers to the uniformity of plate thickness that can be expected on a shaped article over the surface of which the current density will vary. The distribution of the plating current is influenced “by the relative distance of any given part of the surface from the anodes. No plating bath has a throwing power great enough to produce a uniform plate thickness on complex” shaped cathodes.

An insoluble anode that will function as an auxiliary anode free from particle dislodging tendencies in both nickel and chrome plating solutions. Auxiliary anodes of the conforming type are found to be desirable when plating objects having irregular surfaces.  

As insoluble auxiliary anodes generally have the same area presented toward the workpiece, uniform current density over the entire surface of the anode is not required. An extremely effective anode has been produced by coating a single area or face of the auxiliary titanium anode, thereby limiting the area coated with platinum while increasing the effective current being utilized.