About: ABOUT Metals casting, metals stamping, and metal wastage in jewelry processing.

Metals, techniques and wastage



We work mostly Gold and Silver (no platinum). Exceptionally we will accept to work on Brass but only for high end jewelry were quality is more important than competitive price. We work brass with the same level of quality than silver or gold.
This page will detail metals weight properties, various techniques that can be used and corresponding wastage and conditions.


METAL ALLOYS COMPOSITION, DENSITY and comparative weights :

NICKEL FREE WHITE GOLD :
Please note that WHITE GOLD is available only in 18k and 14k gold. and NICKEL FREE WHITE GOLD is available on demand , where Nickel (Ni) is replaced by Paladium (Pd) which is very slightly more expensive.
*** It is important to note that Au/Pd is much more difficult to cast and to work with due to a higher porosity level at the surface resulting in little dots that we will treat eventually with recasting and laser correction on the surface.
Nevertheless when working with Au/Pd we will request a little tolerance in this regard for objects offering large flat surfaces.
If everything was perfect about Au/Pd

everyone would be working only with this alloy and the reason why we keep using Au/Ni is not a question of price (very similar) but a question of finish and whiter color with Au/Ni.

CADMIUM :
Our jewelry is normally cadmium free. Sources of cadmium could come only from radom accessories other than standard jewelry findings, chains,gemstones and metal.


Passing from silver to gold or from Gold 14k to gold 18k is not only more expensive as a price per gram, it does also weight more for the same volume .

Precious metals alloy purity and density
Metal composition % base metal Density
White Gold 18k (Au, Pd) 75% 16.5 g/cm3
White Gold 18k (Au, Ni) 75% 16.5 g/cm3
Yellow Gold 18k 75% 16.5 g/cm3
White Gold 14k (Au, Pd) 59% 16.5 g/cm3
White Gold 14k (Au, Ni) 59% 14.5 g/cm3
Yellow Gold 9k 0.38% 14.5 g/cm3
Platinum 950 95% 21.5 g/cm3
Silver 925 92.5% 10.5 g/cm3
Brass Various % 8.4 g/cm3

CASTING Method
Labor:
Casting labor is mostly the work on injection waxes.
Wax is injected into the rubber/silicon mold and is pulled out once it is solid and must be cleaned before being attached on a tree for casting in metal. Extraction and cleaning can be delicate depending on the design.
Sometimes waxes from different molds will be assembled before casting to avoid welding labor on metal parts which result in additional cost.
Why not having them already assembled into 1 single molds?
Because a rubber mold must be cut at least in 2 parts sometimes more in order to open it and extract the injection wax for each piece produced. After casting the cement can be broken to extract the metal piece so it does not need to be reused like the rubber mold does.

Limitations:
Logically a closed object cannot be casted in 1 single part.
The thickness limitations are mostly coming from the fact that liquid injection wax must be able to "run and reach" each part of the rubber mold to have a complete wax. The same thing for the liquid melted metal that must run into the cement crucible during casting process. Extremely thin walls or wires may result into incomplete castings or porosity (small dots visible on the final piece surface.
We work on castable sheets (side of an object) of 0.7 mm minimum for silver (for solidity) and 0.6 mm for gold (on masters) which will result in a 0.6mm to 0.5 mm thickness after filling and polishing.
A simple border separating rows of stones for instance can be 0.5 mm in the 3D design and will be recut by the setter on the final piece to smaller values.
Such standards are part of the verifications and adjustments we will perform on 3D Designs submitted by customers, and in case of intricate designs not fulfilling our standards we might charge for rebuilding the 3D Design entirely..

Gold and Silver Version using the same mold :
Most of the time customers want to save CREATION COSTS by using the same mold for silver and gold versions of the same product. This is generally a bad idea because on the long run we can save money by optimizing a mold specifically for gold productions.
Gold can be thinner and remain strong while silver is soft and bendable.
Silver version of the product will gain in "quality look and feeling" when it is a little thick and heavy.

WASTAGE
The losses in metal will mostly be generated during filling (cleaning with sandpaper to remove the porous and grainy surface for the rough castings) and during poling stage.
Our worker has an allowance to waste a small percentage in"flying dust".
The power that can be retrieved in the worker's table must be melted and recycled at a refinery (losses and costs".

EXAMPLE :
It is easy to understand that a flat plate of gold 1 mm thin will lose 0.15 mm at filling and polishing (both sides) and polishing which represent 15% of its weight, while a 3 mm thin of the same size will lose the same amount of dust but which will represent a smaller percentage on the total weight.
Now if a pattern is cut out on the entire surface we also must go into each hole to clean the edges and this generates more losses.

We use apply 4 levels of wastage depending on the designs. :
- 20% Thin and intricate jewelry
- 18% Thin surfaces
- 15% Normal rate
- 10% heavy massive pieces not intricate.

Hydraulic Stamping Method :
This method is appropriate for thin plates or metal to be produced in mass.
It can punch a pattern in relief, engrave a text or cut out the outline or patterns from a thin plate.
The advantage is the speed and less filling and cleaning work on the piece than can almost by polished immediately after processing.
The downside is the cost and the time for preparing the tooling

Tooling:
The Stamping Heads are mostly of 2 kinds.
One of them will cut out holes or outline (cutting heads) while the other type is only punching and engraved pattern or a text on the surface. The result is the use of multiple heads to perform a specific piece
These heads can be prepared from a 3D Design or from an image (leaving us to perform the tracing job). The file is passed to a CNC machine that will cut the patterns into a Stamping Head directly in the metal (performed by specialized factory working for various industries). This will then be calibrated for the stamping machine to ensure a correct alignment and start the production.
This complicated process is the reason why this technique can be used only for large productions and most of the time it is best so make samples and adjustments using casting method before investing money and time into Stamping Heads.

Costs to create Stamping Heads :
Starting at $200 for a small tag it can go up to $600 or more for a large bangle.
Once this investment made the labor cost per piece will then be much cheaper than using casting method.

By Hand :
Wire chokers, flat chokers or bangles can be done by hand by laminating metal plates and sawing a pattern before reshaping the final piece.
We can also create custom designed chains by hand (round link section) , or from casting, as long as the links are not too small (6 mm and up).


Useful Links about Jewelry and Gemology

Laboratories & schools
www.aigslaboratory.com
(A.I.G.S. Laboratory)
www.gia.edu
GIA)
www.gemresearch.ch
(GRS)
www.igiworldwide.com
(IGI)
www.ssef.ch
(SSEF)
www.gubelinlab.com
(Gubelin)
www.gemnantes.fr
(D.U.G. France)
Knowledge
www.fieldgemology.org/
Field trips in the mines
http://webmineral.com
About minerals
www.ruby-sapphire.com
The best seller
www.mindat.org
Mineral database
www.themelis.com
Another famous gemologist
http://gemme.la.rca.fr
Blog gemmology and opals
www.opalinda.com
Blog gemmology and opals
beyond4cs.com
Free gemology courses and resources
Forums & Networks
www.gemologyonline.com
The rendez-vous gemology
www.geminterest.com
French equivalent
www.pricescope.com
All about prices
www.diamondse.info
Mostly about prices
http://polygon.net/
All about everything
www.ganoksin.com
All about everything
Associations
www.thaigemjewelry.or.th
(TGJTA)
www.crg-dug.frm
Gemology Research center
www.gemstone.org
(ICA)
www.agta.org
(AGTA)
www.gemsociety.org
(IGS)


This page is relative to jewelry design, wax modeling, wax printing, jewelry production and more specifically about precious metals, gold jewelry, silver jewelry, brass jewelry, molds, casting, stamping and wastage. Our jewelry designers working by hand or on computers help in the modeling of custom jewelry. We are jewelry manufacturers in thailand making gold jewelry and silver design and production of jewelry lines in our jewelry factory. We do custom made jewelry and offer design services in order to provide a complete solution to our customers overseas.