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CASTING
– Snapshot of an Industry
Based on 34 years in the industry, Anthony Eccles, managing director of Apecs
Investment Castings Pty Ltd, reports on the major developments he has witnessed in
investment casting for the jewellery industry.
Major developments:
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. |
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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.
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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 |
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.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. |
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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. |
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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
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.
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The past and the future
Now for some history ...... Lost wax casting has been used as a tool for the production
of jewellery for at least 3,000 years, though not to the extent it has been used since the
end of W.W.II. At the time, jewellers in England and Germany began adapting dental casting
machinery for jewellery casting.
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In 1950 the jewellery industry in Australia, was a three tiered structure
with manufacturer, selling to wholesaler, selling to retailer and each kept to their
speciality area. The wholesaler would place orders with the manufacturer, in preparation
for the selling season. Standard lines sold year in, year out in quantity. It took a long
time to prepare dies for new designs. By 1970 wholesalers could no longer finance the
large inventories they carried and the product could not carry the three margins.
Simultaneously, casting had made an impact - able to reproduce both the large quantities
when required and small orders, economically, as well as producing new design ranges in a
short time frame. Today, these developments have already had a profound affect on the
industry, as there is now a greater awareness of the attributes of casting. Indeed many of
the pieces cast today could not economically be made any other way. |
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Until now all master patterns have been handcrafted. There is now another stream
developing for the manufacture of mass produced jewellery. Currently, we have computer
generated designs which can be fabricated three dimensionally in plastic or wax by stereo
lithography and then cast, without going near a jewellery bench until clean up time. There
is now a need for jewellery designers with computer skills able to understand CAD/CAM and
apply it to the manufacture of jewellery.
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The jewellery industry is a fashion industry and there will always be the
requirement for individual hand made pieces designed to suit beautiful, individual
gemstones. Casting is not the be-all-and-end-all of jewellery manufacturing. Casting is
only one tool in the jewellery designers and manufacturers kit and manufacturers, but it
is a powerful one. One facet of jewellery design is hand making and forming in wax; the
original method by which jewellery was first fashioned for casting. This gives another
dimension to jewellery design which can allow a different set of design parameters, able
to achieve results not otherwise obtainable. A casting can only be a reproduction of an
original piece which has been created, so there is a greater need for more designers and
design courses for apprentice jewellers.
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*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
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Text reproduced from the article in "Australian
Jeweller"
Yearbook 1998.
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