The Electroforming process is virtually the same as electroplating, but its purpose is entirely different. Electroforming involves electrolytic deposition of metal onto a pattern until the required thickness is achieved; the pattern is then removed to leave the finished part. Whereas the typical plating thickness of pieces formed using electroforming is only about 0.05 mm (0.002 inches) or even less, electroformed parts are often substantially thicker, so the production cycle is proportionally longer.
Patterns used in electroforming are either solid or expendable. Stable patterns have a taper or other geometry that permits the removal of the electroplated part. Expendable patterns are destroyed during part removal; they are used when part shape precludes a stable pattern.
Expendable patterns are of two types. They are (i) fusible or (ii) soluble.
- The fusible pattern type is made of low-melting alloys, plastic, wax, or other material that can be removed by melting. When non-conductive materials are used, the pattern must be metalized to accept the electrodeposited coating.
- Soluble patterns are made of a material that can be readily dissolved by chemicals; for example, aluminum can be dissolved in a sodium hydroxide (NaOH).
Electroformed parts are commonly fabricated of copper, nickel, and nickel-cobalt alloy materials. Applications of electroforming include fine molds for lenses, compact discs (CDs), and digital versatile discs (DVDs); copper foil is used to produce blank printed circuit boards, and plates for embossing and printing. Molds for compact discs and digital versatile discs represent a demanding application because the surface details that must be imprinted on the disc are measured in μm(1 μm = 10-6 m). These details are readily obtained in the mold by electroforming.