Jewelry Design Technology
CAD/CAM and CNC
At jeweler’s benches across the world, a master wax carver will sit with a detailed jewelry rendering and begin a painstaking subtractive and additive process to create a wax model.  Tiny chisels, modified dental tools, slender heating elements, a steady hand, and a jeweler’s eye all collaborate in this first step to bring a rendering out of the realm of ideas and into a three-dimensional piece.  Indeed, this process can require hours of meticulous effort, especially considering that it’s not uncommon for multiple models to be carved in order to produce a single piece of jewelry.  

These days, however, jewelry designers are able to accomplish this task without both the jeweler and the master wax carver. Computer aided design and modeling, referred to as CAD, has revolutionized and automated what was once a meticulous skill of the hand.

CAD debuted as an engineering technology in the 1960s.  Used primarily as a drafting tool for the automotive and aerospace industries, the two decades following have seen great evolution in the software capabilities from its 2D origins. Wireframe and solid modeling have allowed designers to create three-dimensional renderings that could be duplicated, re-sized, altered, and most importantly, converted to computer aided manufacturing, or CAM.  As personal computers became more affordable, their use became more widespread, and by the late 1990s, the application of CAD/CAM software became more ubiquitous in jewelry manufacturing.  The concurrent advancement of computer numerical control, or CNC, provided jewelers with yet another way of translating CAD designs into working production models.

CAD is a creative tool with staggering capabilities. Sketches and illustrations can be imported into a software program and converted into graphic vectors.  Design also can be initiated within a program using a mouse or stylus to produce photorealistic renderings that can be rotated, colored, and defined. Specific dimensions can be set, defining points of elevation, raising features, and adding textures.  Essential, too, is the fact that the weights of gemstones and metals can be calculated in the rendering process. The rendering can be altered easily or saved for later use.  The most widely used CAD modeling methods are solid modeling, surface modeling, relief modeling, subdivision modeling, and combinations of these four approaches.

Solid modeling is used for designing uncomplicated geometric shapes with hard angles.  For graceful and flowing shapes that also incorporate geometric shapes, surface modeling is used. Subdivision modeling is relatively new and works as a combination of solid and surface modeling:  it has been described as akin to working with clay.  Design elements can be pushed, pulled, and divided, creating a more hand-crafted appearance in the final product.

A CAD rendering can be exported to one of two machines in order to produce a model that can be molded and cast:  rapid prototyping machines, which produce an additive process, or computer numerical control milling machines, which is subtractive.  In order to reproduce the rendering, rapid prototyping machines typically use a thermoplastic building material—one for the actual structure (the positive space of the rendering), and one for structural support (the negative space of the rendering). The building materials come in contrasting colors, typically green and red.  The support material is soluble so that it can be eliminated before casting.  Layers are systematically built up through a process referred to as “stepping.”  Rapid prototyping models are fragile and frequently cannot withstand the molding process. A thermoplastic prototype is often cast directly into metal in order to create a production model.  While some hand-alteration of a prototype is possible, only minor adjustments can be made without remodeling.

On the other hand, CNC milling machines can interpret CAD data into 250,000 separate commands or more, carving directly into standard jeweler’s wax. CNC milling is the robotic equivalent of the master carver, beginning with a block of wax and removing material to reveal the designed structure. Because jeweler’s wax is used, CNC milled models can be manipulated by a skilled wax carver to create modifications or corrections. Wax models also can be molded more easily, as jeweler’s wax is harder and more durable than the thermoplastics used by rapid prototyping machines.

While CAD/CAM and CNC may represent the future of jewelry design and manufacturing, will they ever truly replace the hand of the artist?  It is hard to imagine a jeweler’s atelier without the master craftsman dexterously creating a custom jewel for a discerning clientele; however, with newer CAD versions specific to the jewelry industry, which even allow operators to program in modest “mistakes” to lend an organic, handmade effect, the future of jewelry is limited only by the imaginations of its designers.


Twist Ring by Julia Behrends.
Images by Laser Star Technologies.

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