How does a new product go through the prototyping process?

Prototype Development

3-D Systems' Sinterstation Pro SLS System performs selective laser sintering, one of the additive manufacturing methods described below.
3-D Systems' Sinterstation Pro SLS System performs selective laser sintering, one of the additive manufacturing methods described below.
Photo Courtesy of 3-D Systems

There's a bountiful variety of methods that can now be used to take your product from the blueprints and into your hands. Providing you aren't planning on time-consuming methods like building the product from scratch, you'll probably be turning to the world of rapid prototyping for a solution.

Rapid prototyping first emerged in the late 1980s in the form of stereolithography. The word might be a mouthful, but the idea is ingeniously simple. What isn't so simple is determining the exact name for this group of technologies. Rapid prototyping is actually just one category in a broader range of applications. Machines that can churn out 3-D models of new design concepts also have a number of other uses. These might include creating multiple models of a product for market testing and refinement, as well as for custom or short run production. Because of the diversity of technology, products and uses of those products, there's no single overarching terminology structure.

Examine the field carefully, though, and we see what all these technologies have in common is they create something by adding substrate, not taking it away. So a basic general term could be additive fabrication. Beyond its earliest manifestation as stereolithography, other terms used over the years include solid freeform fabrication, automated fabrication, rapid technologies, layered manufacturing, digital fabrication, 3-D printing -- it's quite a list, and there are even more candidates out there.

Despite the variations in name, what these machines all have in common is they join extremely fine layers of material onto each 3-D creation, layer by layer, until they have a finished prototype ready to go. The two key components of this system are the substrate that forms the layers and the method that's used to make them stick to together.

Some fields of additive fabrication include:

  • Stereolithography: A laser beam makes a patterned pass over the surface of a vat of liquid photopolymer resin. The resin hardens as the laser hits and the object is lowered slightly for the laser, usually UV, to make another pass.
  • Selective Laser Sintering: This system also makes use of a laser, but works by melting layers of thermoplastic powder and other materials like polymers.
  • Laminated Object Manufacturing: In this method, sheets of material are rolled into range, cut in the desired shape with lasers and adhered to the layer below.
  • 3-D Printing: An inkjet head applies liquid adhesive to layers of powder.
  • Electron Beam Melting: This method can make and repair dense metal parts by using an electron beam (more powerful than a laser) to melt layers of metal powder like steel, titanium and cobalt chrome parts.
  • Fused Deposition Modeling: Strands of plastic filaments or pellets are warmed while passing through a nozzle and melted into place, where they harden and bond.

Depending on the procedure used, support may be necessary for overhangs or undercuts in a part's design. If needed, this can be accomplished either by manual design or by automatic technique, and any supporting structures are usually brushed, dissolved or melted away afterwards. Other postproduction steps may include curing (or baking) a prototype with intense light and applying a finish or a hardener.

Despite the benefits of rapid prototyping, there are some drawbacks. While not taking weeks and months to build a prototype, it does still take a substantial amount of time for all those little layers to be laid down. Waiting hours, even a few days, for prototypes is the norm. The process and equipment can also be very expensive, with larger models costing several hundred thousand dollars. Many smaller and more affordable machines are available, however, and some companies charge hourly to prototype specs submitted by designers.

Now that we've got our prototype, what are we supposed to do with it?