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All About Metal Plating
The Art Of Plating
Metal Plating is the method of applying a metallic coating to another
material. There are many reasons to plate objects. They can be applied to
almost any coarse material. The most common surfaces that are plated are
metals and plastics. Plating can be used for different reasons. Some
objects are plated to increase their sturdiness and provide a hard shell
for whatever it is plate on. Some are plated to avoid corrosion, and a few
are plated just to give off an attractive finish.
There are a few ways of conducting the metal plating process. There is
electroplating, electroless plating, metal spraying, and vacuum
metallizing. Among these, the most popular is electroplating.
The plating of other metals mainly depends
on the physical properties and composition of the metal that is going to
be plated. Some may not be good conductors, thereby making poor Cathodes
for the electroplating process. Others may not plate well because of a
strength-weight ratio of the metal to be plated. If the strength to weight
ratio is low, then the plating material may not hold well with the metal.
If the strength to weight is high, then the plating will hold well to the
metal, ensuring a good bond between the two. Ideal metals to plate are:
Steel
Brass
Zinc Die castings
Copper Alloys (Zinc and tin)
Beryllium
Aluminum
Before a metal is plated, it must go through a process of pretreatment. In
the pretreatment, the metal is cleansed and prepared with other chemicals,
that will quicken or make a more reliable adhesion with the plating metal.
A design consideration for this would be to make the object to be plated
have certain design characteristic that
will make the plating even and stable.
The actual plating of metals can be divided into three groups. These are:
Barrel
Rack
Strip (reel-to-reel, continuous)
Barrel Plating is used when the plating is
done inside of a perforated barrel, and the barrel is rotated to even the
plating. It is mainly used in the plating small diverse objects, devoid of
sharp and long edges that tend to plate badly.
Rack Plating is used for plating objects that are too heavy, too large, or
too complicated to barrel plate. These can vary from small things such as
keyholes, to large roller. Most rack plating setups, are made up of copper
rods, that conduct electricity very well, and are very durable. The
objects are clipped to this copper rack and then put in to the electrolyte
solution. The placement of the copper rack in the solution is crucial
because if the rack is placed incorrectly, the plating may be lop-sided
and uneven.
Strip Plating is used when the object happens to be just a strip of metal.
This strip of metal is then put through different process stations (or
solution tanks), where they are plated at different levels. It can be used
for selective plating.
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