How 3D Printing Works

By Jason Griffey |

Editor's Note: This is the first of a series of posts excerpted from Jason Griffey's Library Technology Report "3D Printers for Libraries."

The simplest way to understand a 3D printer works is to imagine it as a machine that makes bigger things out of smaller blocks. In some cases the “blocks” are a powder, in some they are melted plastic, or they may be a ultraviolet light sensitive resin, but always the process is large things being made from smaller substrates. A 3D printer is a simple sort of robot that understands how to manipulate the raw material it’s working with in three dimensions rather than just two, as an inkjet or laser printer does. This type of manufacturing is also called additive manufacturing, as opposed to more traditional subtractive manufacturing, where material is removed from a larger sample to create custom shapes in a process like milling, lathing, or CNC (computing numerical control) machines.  

 Imagine an inkjet printer that instead of printing ink extrudes hot plastic that cools quickly. Think of it like a hot glue gun where the plastic is solid, then gets heated to a liquid state, and then cools again into a solid. If it printed this plastic on a piece of paper, you’d end up with a slight raised design being “drawn” on the paper by the printhead moving back and forth across the paper (the X dimension) and the paper being moved through the print area (the Y dimension). Those of us old enough to remember the days when color printing was very expensive might recall hot wax printers that did basically this.

 With a 3D printer, you add the last of the spacial dimensions, height, by moving the printhead and printing substrate (usually called the build platform in this case) apart from each other. In our inkjet analogy, imagine that you put the printhead on an elevator that could move it closer and farther away from the paper. If you do that while the printhead is putting down plastic, you can just keep them moving farther and farther apart, layer after layer, in the Z dimension. Over time, you end up with an object made of very thin layers of this plastic. That’s what most 3D printing is like.

 This is the basis for almost all of the 3D printing that you have seen in media over the last few years, and almost all 3D printing that libraries have been involved with. Called fused deposition modeling,  it isn’t the only type of 3D printing, just the most affordable.

 In future posts in this series, I’ll describe other 3D printing types: selective laser sintering, stereolithography, laminated object manufacturing, and electron beam melting. While many of them are well beyond the means of most libraries, prices are likely to go down dramatically as soon as patents expire on the core technologies behind the printing methods. This is central reason that fused deposition became inexpensive so quickly during the past five years. Most people that follow 3D printing believe that laser sintering will follow suit shortly, as a key patent to that technology expired in January of 2014.

The next post in this series will be about the printing technology most central to libraries at the current time, fused deposition modeling, and then we’ll take a look at the other options that may be coming in the next 3-5 years.