Electroforming

Electroforming process

Electroforming is a metal forming process that forms thin parts through the electroplating process. The part is produced by plating a metal skin onto a base form, known as a mandrel, which is removed after plating. This process differs from electroplating in that the plating is much thicker and can exist as a self-supporting structure when the mandrel is removed.

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 nonmetallic micromolded objects.

Process

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.

The mandrel is made of a non-conductive material it can be covered with a conductive coating. 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 metalized form.

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”. New technologies have made it possible for mandrels to be very complex. In order to facilitate the removal of the electroform from the mandrel, a mandrel is often made of aluminum. Because aluminum can easily be chemically dissolved, a complex electroform can be produced with near exactness.

Advantages and disadvantages

The main advantage of electroforming is that it reproduces the external shape of the mandrel within one micrometre. Generally, forming an internal cavity accurately is more difficult than forming an external shape, however the opposite holds true for electroforming because the mandrel's exterior can be accurately machined.

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.

Tolerances of 1.5 to 3 nanometres have been reported.^{[citation needed]}

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.

See also

• LIGA
• Electrotyping

Further reading

Spiro,P. Electroforming: A comprehensive survey of theory, practice and commercial applications ,London 1971.

External links

• http://www.drc.com/metrigraphics/electroforming.htm
• http://www.nicoform.com/definitions/electroforming