3D printing back to the future

A market explosion of 3D printers now available in all manner of sizes, price points, and mediums compete for your attention. The maker movement is in full swing. Additive manufacturing is no longer an oxymoron. 3D printing has arrived. But where did this technology come from? It's actually been there all along. Heavy. Let's ramp it up to 88mph and take a look back to 1985 or so.

Each day edges us closer to the holy grail of additive manufacturing, and you don't even need to know the capital of Assyria to seek it out. The ultimate goal: to fabricate any production-quality part quickly, easily, and cost effectively without the “producibility” limitations of most conventional manufacturing methods like CNC milling. That's a rather aggressive goal, and thirty years ago the concept was only marginally more plausible than a time-traveling DeLorean. Interestingly enough, much of the underlying technology contributing to today's 3D printing momentum was gainfully employed in engineering all this time, but dutifully serving more modest goals.

Ye olde 3D printing

Back then we didn't bundle a variety of tech under the snazzy 3D printing moniker. Most of the technology was instead recognized by the original processes – Stereolithography Apparatus (SLA), Selective Laser Sintering (SLS), Fused Deposition Modeling (FDM), and so on. Yes, we're engineers and we love acronyms. The STL files you deal with today? That heritage comes from STereoLithography. Cue the more you know.

Collectively these technologies were widely referred to as Rapid Prototyping (RP), as in the opposite of painfully slow prototyping. RP was simply a faster and cheaper way to create physical prototypes of newly designed parts to help refine form, fit, and function in a world where 3D CAD models were not yet ubiquitous.

Other long-term use of RP technology include:

• Mockups and Assembly Interference: Before maintaining master models was practical in CAD, a physical mockup was often constructed at scale using representative parts. In the early days, this was chiefly accomplished with carpentry. Yeah. Wood. Sometimes clay. Great Scott, indeed. Even in today's model-centric world physical mockups using RP are often used for accelerated development or to test intricate assembly concepts. Interference checks for design changes within complex assemblies, especially in applications such as aircraft modification, can be quickly validated by installing a rapid prototype part in a real assembly. Even though much of these activities can now be accomplished via virtual model-based methods, use of RP for these purposes remains widespread
• Maintenance concepts: RP is useful not just for static assembly checks, but also for maintenance, usability, and assembly sequencing concerns – including how parts and assemblies are installed, removed, or otherwise serviced. Usability and ergonomics can be virtually modeled using modern software tools, but using a real physical equivalent allows quick validation with end users at very low cost. Better to find out you can't physically remove a part while it's still just made of some cheap thermoplastic resin.
• Low-Rate Mold Fabrication: Stereolithography is precise enough for low-rate tooling used for parts such as fiberglass lay-up or similar processes. High rate production tooling for these types of parts often involve costly mold setups, that often have to be thrown away entirely if the design changes in an unexpected fashion. When risk of mold rework is high, molds fabricated using RP are fantastic for risk and cost mitigation, especially with contoured or lofted surfaces from aerospace applications. Once the design is fully validated, full production tooling can be built using conventional materials.

As we look forward to what 3D printing will bring in 2015 and beyond, expect new and interesting innovations that help push the envelope of design and engineering. But don't for a minute think of 3D printing as an overnight phenomenon; it's a revolution thirty years in the making. Now if only we could 3D print Mr. Fusion, we'd be all set.