Gilding net shaped manufacturing

Tweaks to an old process allow the manufacture of short run, net shape formed products with exceptionally good surface finishes and low weight. Tom Shelley reports A firm in West London uses electroplating and electroforming to produce finished parts with an exceptional degree of precision on surprising substrates. They can even electrodeposit copper, silver and gold onto wood and other organic materials. Developed to produce a decorative finish to fittings in a Hindu temple in Neasden, the wood plating process is but one example of what can be done with modern versions of a mid nineteenth century invented, rapid prototyping and short run manufacturing technique. Richard Lewis, managing director of BJS explained that the trick to electroplating wood is to first deposit a flash of silver, employing the same chemistry used to make mirrors. Copper is then heavily electrodeposited onto the silver, on top of which is deposited the decorative gold or silver finish. The main business of BJS is in electroforming to produce engineering products, modern silverware and replica antiques. By laying down a silver flash on a moulded silicone rubber former, it is possible to produce an electroformed item with re-entrant angles. The silicone rubber is pulled out afterwards. An electroformed replica antique silver column base shown to Eureka had been made by this method all in one piece whereas the base of the original had had to be made of four stamped out parts. BJS specialises in working with silver, both because of the silverware side of the company, and also its very high thermal conductivity. This has led BJS to be the main global manufacturer of high precision heat exchange units used in the biotechnology research field. So good is BJS at electroforming that its replica antiques look exactly the originals down to exact reproduction of every blemish and scratch. Neither they nor parts made for engineering purposes normally require any finishing. Electroforming easily produces very light weight sub millimetre wall thickness parts that would be difficult if not impossible to make using thin walled investment casting or by any other method. Particularly remarkable products include the part shown in our illustration, used to repair the eye socket of a worker injured in the Piper Alpha disaster and replica musical instrument trumpet cones. BJS Biotechnologies email BJS Pointers * A process has been developed to allow wood to be electroplating * Improvements in electroforming based processes allow the net shape formed short run manufacture of finished, thin walled parts of complex shape with re-entrant angles in a single operation