Snapshot of an Industry

1. A more realistic acceptance of the role of cast precious metal.

When I began my casting career, casting was frowned upon as an inferior method of manufacturing jewellery. Some of my customers did not admit to using castings for some years. One large Melbourne retailer had a sign in the window stating, "We do not use castings" with a photograph showing a broken cast ring titled, "This is cast" and a sound ring titled, "This is not cast". Fortunately, this thinking does not exist today.

Casting has taken part of the role earlier filled by presswork and is now used as a forming tool like any other facet of manufacturing; its forte being the ability to economically handle very short runs and being able to make the complex, fine, designs as dictated by fashion and the designers of jewellery.

2. An improvement in the sharing of knowledge

The old barriers to the sharing of knowledge have broken down due to world forums such as the Santa Fe Symposium on Jewellery Manufacturing Technology* which has run now for ten years and The International Symposium on Gold Jewellery Technology* held in Vicenza each year.

Although a large proportion of subjects at the Santa Fe Symposium relate to casting, all aspects of the latest technology and equipment pertaining to manufacturing jewellery are discussed. Subjects as diverse as, "CAD/CAM in the jewellery Industry" by Kevin Abernathy; "Refining Jewellers Wastes" by Roland Loewen; "Casting Gemstones in Place" by Ajit Menon and "Chip Carving Hard Wax" by Chuck Hunner are discussed

3. Improvements in equipment.

From the early spring-driven centrifugal casting machines using gas torch melting, where the operator usually judged the temperature of the metal by eye, we've moved to today’s state-of-the-art induction melting, vacuum or centrifugal casting machines. Programmable by inbuilt computerization, the operator loads the flask into the machine, loads the crucible with the pre-weighed metal, pushes the program and start buttons, the metal is melted and cast within minutes - indeed a major improvement.

Wax pattern production is still reliant to a large degree on operator skill. Wax injecting machines have made advances in technology for mass production. A number of moulds can be automatically presented in turn to the nozzle and the correct mould clamp pressure and wax pressure is applied by means of computer analyzed indexing marks on the rubber moulds.

Beads of metal on the castings, from bubbles of air trapped on the wax pattern, are now a thing of the past because of the vacuum investment mixing machines now in use.

4. Improvements in materials

The investment makers, conscious that consistency of their product is paramount, have improved the quality of investment. Waxes are now high tech products, the blending of plastics with the wax requires specialized equipment and techniques and has given the waxes improved strength and surface finish.

Moulding materials likewise have been improved. It is now possible to obtain a mirror-like finish on the wax pattern with the advent of silicon rubbers. Many of the precious metal formulae have improved with the addition of silicon to the zinc containing alloys.

Now we have sterling silver which has the attribute of being fire stain free with an increased resistance to tarnish making it easier to handle in production as well as requiring less cleaning as retail stock.

5. Improvements in technique.

Initially jewellery casting went through a trial period when everyone attempted to cast everything. People were asking too much of the process; wanting to cast complete items which should have been componentised. Now, patterns are now designed to make use of its advantages. By being more conscious of quality control at each step of the process, we now produce much improved castings which require minimal time at the bench, being easy to finish and set without the breakage's early castings displayed.

*All papers of The Santa Fe Symposium on Jewellery Manufacturing Technology are available in a bound year book and video form:

The Santa Fe Symposium 7500 Bluewater rd. N.W. Albuquerque, New Mexico, USA.

*Gold Technology Bulletin is available free by applying to:

The World Gold Council, Kings House, 10 Haymarket, London SW 1Y 4 BP