How does a jeweler make a ring?

A common method to produce jewelry like rings and pendants is through metal casting, which consists of a number of technologies including lost wax casting. A wax Model is made of an object which is then trapped inside a plaster block. Later, the plaster block is placed inside a kiln until the wax model evaporates. Next, the plaster mold is filled with liquid metal. Once the metal has cooled and hardened, the plaster is dissolved in water and you’re left with a metal copy of the wax model which is ready for post-processing.

Experienced jewelers are capable of making wax master models by hand using numerous carving tools with great precision and accuracy. However, it can be time-consuming and human error inherently leads to jewelry pieces being slightly different from one another if you consider that each new piece requires its own new wax model. In order to avoid this, wax models are created using another mold. Basically, the process of mass production requires creating a mold for wax master models and then new plaster molds for each piece casted with metal.

To make custom jewelry like wedding rings using traditional methods, the master would usually require somewhere between 2-4 weeks, with some companies even asking for at least 6-8 weeks to fully complete an engagement ring. This is where CNC machining really shines through, helping to save time and cut down the costs for creating a piece of jewelry.

How CNC machines help to create master models for casting?

Since metal casting is one of the most popular methods to create jewelry, manufacturers tend to focus on improving the process of making master models to speed things up. Instead of hand carving pieces from wax, makers use Cnc Machines. If a wax copy of a jewelry piece is created with CNC technology, it may allow more complex and precise geometries to be produced compared to a hand-carved piece. For example, engraved details can be done before casting. Machines also operate faster but they would require a CAD file of an object to be created.

To work the block of wax, several types of CNC machines can be used such as milling, turning and water jet. To remove material from intricate areas, a CNC machine should be equipped with a thin type of mill and if different types of surfaces required, the process would include switching tools for other sizes and angles. Depending on the number of axis a machine has, less tool changes needed and more possibilities are available but if a jeweler creates a specific type of object, they usually select the most suitable machine optimized for those.

The downside that mechanical milling, drilling and turning CNC machines may have for working castable wax blocks – the deformity of material. Since wax is quite a soft material, mechanical tools can accidentally heat it up during the process and warp some parts – especially in thin and intricate places. CNC machines that are fine-tuned for creating master models usually have special cooling systems which prevent the wax from crooking under a tool and delivers smooth surface finishes. Another type of CNC machine which is often used for carving master models is water jet. Water jet cutting is quite similar to milling but instead of mechanical mills, it operates with a flow of water mixed with abrasive materials. Water jet CNC machines don’t heat the piece of wax so much and no tooling changes are needed. If a water jet machine has many axis or a turning table, it can produce good results like that of milling machines.

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