We are offering end-to-end casting services for jewelry industry.
Everything that will ever be cast starts with a Model.
The model can be made out of many different materials. The model can be an item
that has already been produced in metal, a wax carving, a plastic carving, or just
about anything that will not react to the mold rubber negatively.
If you have an idea for an item that you would like cast but cannot carve wax or
shape metal, we can help. We have model makers that can take your idea and turn
it into a work of art. Model making is often done on computer and then the model
is produced with a Rapid Prototype Machine. This method is not the cheapest but
generally produces the best results if carving or fabricating your own model is
not an option.
Molds are used to produce wax replicas of your model. There are two kinds of molds
that we produce.
The first type of mold is the Rubber Vulcanized mold and is used, generally for
metal models that can with stand heat to approximately 350 degrees.
The second type of mold is the Room Temperature Vulcanized mold and is usually used
for wax or plastic models. Both types of molds reproduce your models accurately.
By injecting molten wax into the mold, waxes replicas of your item will be produced.
Waxes can be injected into molds about once every two to three minutes. This allows
for mold cooling and wax hardening.
Once we have the wax replica of your item we then put them on wax trees. The wax
trees will often contain as many as one hundred or more items or as few as one.
Flasks and Investment
Once the wax trees are finished, they are placed in a metal flask. The flask will
then be filled with a plaster investment that covers the wax tree. The plaster Investment
dries and is then ready for the casting burn out ovens.
Burning out the Wax
After the Investment has completely dried, the flasks are place into the burn out
ovens and a 12 to 16 hour burn out cycle begins. This is where the Lost Wax Casting
name comes from. The wax is slowly burned out to leave a plaster Investment mold
that will be used to pour the casting metal into.
The casting is done by placing the flasks in a centrifuge or a vacuum casting machines
and then heating the metal and pouring the metal into the flasks. So that we can
handle large capacity orders, we use large induction heaters to melt the metal for
Cutting the Cast Tree
The result of the casting is a metal tree of your items. When the metal trees come
out of casting they must be cleaned and prepared for cutting from the tree. Each
cast item must be cut from the tree.
Desprueing is the process of grinding the sprue off of the item so that evidence
of the casting process is removed.
We have a number of ways to despure items from rotary tools to grinding wheels.
Because much of the metal from desprueing is unrecoverable and must be refined,
desprueing is about 60% of the total cost of finishing or more if it is gold.
There are numerous ways in which your products can be finished such as; Hand polishing,
tumble polishing, satin wheel finishing, sand blasting and the list goes on...
Final stage in gold jewelry making process is setting stone. Stone setting is also
having numerous ways.
Types of stone setting
There are thousands of variations of setting styles, but there are several fundamental
A Bezel Set Sapphire
The earliest technique of attaching stones to jewelry was bezel setting. A bezel
is a strip of metal bent into the shape and size of the stone and then soldered
to the piece of jewelry. Then the stone is inserted into the bezel and the metal
rubbed over the stone, holding it in place. This method works well for either cabochon
or faceted stones.
Prong set diamonds
Prong setting is the simplest and most common type of setting, largely because it
uses the least amount of metal to hold the stone, thus showing it off to its best
advantage. Generally it is simply some number of wires, called prongs, which are
of a certain size and shape, arranged in a shape and size to hold the given stone,
and fixed at the base. Then a burr of the proper size, is used to cut what is known
as a "bearing", which is a notch that corresponds to the angles of the stone. The
burr most often used is called a "hart bur" that is angled and sized for the job
of setting diamonds. That bearing is cut equally into all of the prongs and at the
same height above the base. Then the stone is inserted so that it goes into all
of the bearings, pliers or a pusher are used to bend the prongs gently over the
crown of the stone, and the tops of the prongs are clipped off with snips, filed
to an even height above the stone, and finished. Usually a "cup burr" is used to
give the prong a nice round tip. A cup burr is in the shape of a hemisphere with
teeth on the inside, for making rounded tips on wires and prongs. There are as many
variations of prong settings as there are stars in the sky - 2 prongs up to 24 or
more, many variations involving decoration, size and shapes of the prongs themselves,
and how they are fixed or used in jewelry. But the method of setting is generally
the same for all of them.
Channel set diamonds
Channel setting is a method whereby stones are suspended between two bars or strips
of metal, called channels. Often when setting small stones and the bars go in a
linear line with the design it is called channel setting, and when the bars cross
the lines of the design, it's called bar set. The idea is the same, though. The
channel is some variation of a "U" shape, with two sides and a bottom. The sides
are made just a bit narrower than the width of the stone or stones to be set, and
then, using the same burs as in prong setting, a small notch, which is again called
a bearing, is cut into each wall. The stone is put in place in those notches, and
the metal on top is pushed down, tightening the stone in place. The proper way to
set a channel is to cut a notch for each stone, but for cheaper production work
sometimes a groove is cut along each channel. Also, since the metal can be very
stiff and strong, this is a situation where a reciprocating hammer, which is like
a jackhammer but jewelry sized, might be used to hammer down the metal, as it can
be difficult to do by hand. Then, as always, the metal is filed down and finished,
and the inner edge near the stones cleaned up and straightened as necessary. As
with all jewelry, there can be many variations of channel work. At times the walls
will be raised - sometimes a center stone will be set between two bars that rise
high from the base ring - or the channel might just be cut directly into some surface,
making the stones flush with the metal. It is still channel setting, though.
Example of bead set diamonds
Example of pave set diamonds
Bead setting is a generic term for setting a stone directly into metal using gravers,
also called burins, which are essentially tiny chisels. A hole is drilled directly
into the metal surface, and then a ball burr is used to make a concave depression
just the size of the stone. Some setters will set the stone into that concave depression,
and some will use a hart burr to cut a bearing around the edge. Then the stone is
inserted into that space, and the gravers or burins are used to lift and push a
tiny bit of the metal into and over the edge of the stone. Then a beading tool,
which is simply a steel shaft with a concave dimple cut into the tip, is pushed
onto the bit of metal, rounding and smoothing it, pushing it firmly onto the stone,
and creating a "bead". That is the essential method, but there are many types of
setting that use the technique. When many stones are set in this fashion very closely
together, covering a surface, that is called "pavé" - from the French for paved
or cobblestoned. When a long line is engraved into the metal going up to each of
the beads, that is "star set", because of the look. The other common usage is called
"bead and bright", "grain setting" or "threading" in Europe, and other names at
times. This is when, after the stone is set as described above, the background metal
around the stone is cut away, usually in geometric shapes. In the end what is left
is the stone with four beads in a lowered box shape with an edge around it. Often
it is a row of stones, so it will be in a long shape with a raised edge and a row
of stones and beads down the center. This type of setting is still used often, but
it was very common in the early to middle 20th century.
Burnish set diamonds
Burnish setting or flush setting is similar to bead setting, but after the stone
is inserted into the space, instead of using a graver to lift beads, a rubbing tool
is used to push the metal all around onto the stone, not very different from bezel
setting. The stone will be roughly flush with the surface, with a nice rubbed edge
around it. This is a fairly recent type of setting, looks very contemporary, and
the metal is often finished using sandblasting, as it shows off the work very well.