Metal Casting Zone Info Blog

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What two benefits are they of using lost wax casting for jewelry manufacture?

Jewelers who specialize in custom designing often use the lost wax casting method to create one-of-a-kind rings, charms, pendants, or other specialized items out of precious metals.

First the jeweler may sketch an idea on paper, especially if he or she is working with a client.  When the diagrammed sketch is approved, the jeweler then fashions an exact replica of the finished item in a soft, pliable wax.  The wax pattern, or maquette, is fitted with a stem called a sprue, which will create an exit for the wax when it is burned out.

This wax form is weighed to determine the amount of metal that will be needed.  It is then attached to a base and fitted with a tumbler that holds the mold material, which is plaster mixed with water to a cake batter consistency, called investment.  It must be free of bubbles before pouring into the tumbler, so it is placed in a vacuum to remove all the air.  The investment is poured into the tumbler and then taken to a kiln to have the wax burned out.

A jeweler’s centrifuge machine is the tool that injects the liquid metal into the mold.  The mold is taken from the kiln and placed in a holder that has a hollow arm attached to a cup that lines up with the hole in the mold. The pre-measured metal is placed in this small crucible, and then heated with a torch until it is liquid. 

The pin is then released on the centrifuge, and it spins rapidly around while the liquid metal is forced into the tumbler and mold. Once the spinning stops, the tumbler is removed from the centrifuge with tongs (it is extremely hot), dipped into cold water, and the plaster cracks and falls off of the metal inside.

At this point, the beautifully designed object created on paper does not even slightly resemble the blob of metal in the jeweler’s tongs.  This is because the base (or button) and the sprue are now metal like the rest of the design, and must be sawed and ground off with a jewelers’ Dremel tool, which is an instrument much like a dentist’s drill.

Much fine sanding and shaping is done with the Dremel and its attachments, and gradually the original design emerges.  Jewelers’ rouge puts a nice patina on the finish, and after much polishing, the piece is now ready for use.

Having a custom-made, jeweler-designed ring, pendant, charm, or other special item is something to be proud of, since it can define who you are, what your interests are, or what is important your life.

This is a home chemistry experiment being done in safe conditions with properly trained individuals. It seems as if thermite eats through just about everything so even if the material does not melt if it gets to hot it could deform the casting. I would prefer answers not containing the word titanium. Unless you can give an example of where you can get titanium and if its within a reasonable price. I would prefer the material to be somewhat easy to shape.

For years custom designed jewelry has been created using old world techniques dating as far back as the 1800′s. Until recently, almost all-custom designed jewelry was created using these methods. The introduction of Computer Aided Design (CAD) and Computer Aided Manufacturing (CAM) has changed all that and in it’s wake ushered in a whole new universe of possibilities. Designs that were never thought possible can be made to the highest quality standards.

How is Custom Designed Jewelry Made?

Before learning about the benefits of 3D-CAD you’ll need to know more about the custom jewelry design process. Most jewelry is made using a method called lost wax casting. A skilled artisan/jeweler hand carves a jewelry prototype out of jewelers wax using small scalpels and knives. This wax prototype also known as a “model” is placed in a flask and plaster called “investment” is poured all around the model. Once the investment hardens an exact impression of the model is formed inside of the flask. The wax model is burned out of the flask leaving a cavity of the jewelry design.

Next molten metal is injected in the flask mold using vacuum or centrifugal casting. When the metal cools and hardens the investment is broken away revealing the un-finished jewelry casting. This casting is filed, polished and prepped for assembly, which may include setting the gemstones or welding other precious metal parts to the casting.

The process of hand carving the wax prototype has always been the accepted process for creating custom jewelry. The problem with this process is that the human hand can’t be as precise as a computer-aided machine when carving the model. Precision equates to more design possibilities and much higher quality jewelry production. In the end you’ll have a product that looks crisper and won’t be prone to stone loss or breakage.

What is Computer Aided Design?

Computer Aided Design is a sophisticated modeling process using advanced software to plot coordinates for mechanical drawings. These drawings can be exported to various types of prototyping machines called CNC mills or growing machines. CNC mills cut-away material from a block of wax to make the jewelry model. The growing machines layer material from side to side much like a printer to build the model, samples of this process can be viewed at http://www.andrewsjewelers.com/ .The precision of these models exceeds what any human could do while hand carving the jewelry model. Design possibilities become limitless because the 3D-CAD software enables the designer to create parts and design elements that aren’t possible using outmoded tools and methods.

Another benefit of 3D-CAD jewelry design is the ability to see a computer rendering before the final completion of the jewelry. In old methods the jeweler would create crude counter sketches of your concept and the rest would be left to your imagination. Now the designs that the jeweler creates in 3D-CAD can be rendered to photo-realistic images for you to view before making your final decisions.

Choosing a Jeweler for Custom Jewelry Design

Like any other occupation or trade there are good jewelry craftsmen and there are bad ones. It is important to pre-screen your jeweler to determine if he/she is skilled at making custom designed jewelry. Ask to see their portfolio and examine their designs to determine if the flair they have for jewelry design matches your style requirements. Also, pay close attention to their communication and interpretation skills because much can get lost in the translation of your ideas if you’re not careful. Once the jewelry is made its too late to make changes and the typical jeweler will not re-make it again without added fees.

At this point higher qualified and better skilled custom jewelry designers have moved to using 3D-CAD to create their designs. If you feel 2 jewelers are equally matched in aptitude and skills then you should choose the one that is using 3D-CAD design. You’ll pay a little more to have your jewelry created in 3D-CAD but the final results will be amazing. The jewelry will look 1000% better than if it were hand carved and it will last much longer because of the precision of the jewelry model.

Andy Moquin
President
Andrews Jewelers Inc.
andrew@andrewsjewelers.com
716-630-7091

I have a wax figure i would like to cast into metal bColloidald to coat it with some sort of ceramic material except clay to fire melt the wax out leaving a perfect mold for a metal pour. Is this Colloidal silica liquid and I add sand to it or is it the other way around. Or do I need to use something completely different.