Sometimes it seems as if the rapid prototyping industry produces almost as many acronyms as it does parts. There's FDM, SLA, DMLS, EBM and LOM, just to name a few. But the acronyms do serve a purpose since they refer to individual prototyping processes, each with different capabilities.
What increasingly doesn't serve a purpose is the term “rapid prototyping,” which has lost much of its descriptive power for a couple of reasons. For one thing, rapid prototyping doesn't necessarily live up to the first part of its name. And, rapid prototyping machines are increasingly being used for production parts rather than prototypes.
You may think rapid prototyping machines, which use various additive fabrication methods, will by definition create parts faster than traditional manufacturing methods. But high-speed machining centers and even some injection molding operations can turn out parts as fast or faster than rapid prototyping machines.
Don't believe me? Well, consider Protomold. Arguably the speediest of quickturn injection molding businesses, it has honed its high-speed machining and molding operations to the point where it can now produce injection-molded plastic parts in one business day. Protomold's First Cut Prototype subsidiary promises the same for machined plastic prototypes.
One-day turnarounds make Protomold and First Cut at least as fast at supplying parts as rapid prototyping service bureaus and many in-house prototyping operations. “For the kinds of parts we make, we're faster hands down,” says Brad Cleveland, Protomold's president.
Of course, to say rapid prototyping isn't by definition the fastest way to get a part is not to say it doesn't have value. Additive fabrication machines can increasingly produce finished or nearly finished production parts — without the need for tooling or expensive fixturing. Additive fabrication can enable complex part geometries and function integrations that would be too expensive or even impossible to achieve any other way.
Plenty of users have gotten wise to these benefits and started to press their rapid prototyping machines into production duties, particularly for low-volume or custom products. Stratasys, the market leader in additive prototyping machines, reports 42 percent of its customers already make some production parts on their machines, while 11 percent use their machines solely for manufacturing.
So if rapid prototyping machines aren't necessarily the fastest way to make parts and if they don't always make prototypes, what should we call them? I spoke to industry analyst Terry Wohlers during the Rapid 2007 conference and he suggested in passing we call all of the additive fabrication machines “3D printers” and we adopt “3D printing” in place of “rapid prototyping.”
His not entirely serious suggestion may not sit well with those who supply prototyping machines. They've spent years differentiating their fabrication technologies and only a handful of machines, like those from Z Corp., explicitly use technology borrowed from ink jet paper printers. What's more, in common usage, “3D printer” currently refers only to the relatively low-cost prototyping machines, not the pricier models most suited to production-part manufacturing.
That differentiation, though, matters more to those who market the machines than to those who use them. As Wohlers points out, “You have low-cost paper printers for use in the home and higher-cost printers used for commercial printing. They're all printers.”
What he says makes a lot of sense. 3D printing could likewise encompass the entire spectrum of additive prototyping machines — from low-cost models that work as CAD peripherals in the office environment to higher-priced machines destined for the shop floor. As a descriptive term, “3D printing” captures a lot of what makes additive machines special.