Electroforming is a highly specialized process
of metal part fabrication using electrodeposition in a plating
bath over a base form or mandrel which is subsequently removed.
Technically, it is a process of synthesizing a metal object by
controlling the electrodeposition of metal passing through an
electrolytic solution onto a metal or metallized form. More simply,
a metal skin is built up on a metal surface, or any surface that
has been rendered electroconductive through the application of
a paint that contains metal particles. Essentially, a metal part
is fabricated from the plating itself.
This differs from electroplating basically because
the skin is much thicker and can exist as a self-supporting structure
if the original matrix is removed. The object being electroformed
can be a permanent part of the end product or can be temporary
(as in the case of wax), and removed later, leaving only the metal
form, the “electroform”.
The advantage of the electroforming process is that
it reproduces the form or mandrel to within one micrometre without
the shrinkage and distortion associated with other metal forming
techniques such as casting, stamping or drawing. And, since the
mandrel is machined as an outside surface, close dimensional tolerances
and high surface finishes can be held and maintained on complex
In recent years, due to its ability to replicate
a mandrel surface precisely atom-by-atom with practically no loss
of fidelity, electroforming has taken on new importance in the
fabrication of micro and nano scale metallic devices and in producing
precision injection molds with micro and nano scale feature for
production of nonmetalic micromolded objects. Electroforming tolerances
of 1.5 to 3 nanometres have been reported by some precision fabricators.
In the basic electroforming process, an electrolytic
bath is used to deposit nickel or other electroplatable metal
onto a conductive patterned surface, such as glass or stainless
steel. Once the plated material has been built up to the desired
thickness, the electroformed part is stripped off the master substrate.
This process allows high-quality duplication of the master and
therefore permits quality production--at low unit costs with high
repeatability and excellent process control.
Compared to other basic metal forming processes
(casting, forging, stamping, deep drawing, machining and fabricating)
electroforming is very effective when requirements call for extreme
tolerances, complexity or light weight. The precision and resolution
inherent in the photographically produced conductive patterned
substrate, allows finer geometries to be produced to tighter tolerances
while maintaining superior edge definition with a near optical
finish. Electroformed metal is extremely pure, with superior properties
over wrought metal due to its refined crystal structure. Multiple
layers of electroformed metal can be molecularly bonded together,
or to different substrate materials to produce complex structures
with "grown-on" flanges and bosses.
A wide variety of shapes and sizes can be made by
electroforming, the principal limitation being the need to strip
the product from the mandrel. Since the fabrication of a product
requires only a single pattern or mandrel, low production quantities
can be made economically.