The Big Picture - June/July 2013 - (Page 12)

inside output inside output 3D Printing: Putting the ‘Additive’ in Manufacturing By Craig Miller Y ou’re likely familiar with the basic concept of 3D printing, aka additive manufacturing. In short: It’s the creation of a three-dimensional object from a digital model; the object is formed by adding successive layers of material (plastic fi laments) in different designs to form virtually any shape. With this process, you can build just about any type of object. Yes, these “printed” objects are often being used as production prototypes, but you can also create finished, one-off objects. Although this technology seems to have burst onto public awareness just a few months ago, 3D printing has actually been quietly evolving for about three decades. I’ve been fascinated with the concept of 3D printing for a long time, and I’ve worked with some low-end hobbyist kits in the past. This January, I finally bit the bullet: I ordered a factory-built 3D printer, and our company has been printing plastic parts and objects for a few months now. What caused me to take a bite of the 3D pie? It was the emergence of the first “prosumer” 3D printers. Until recently, only two categories of printers were available: hobbyist models that sold for a few hundred to just over a thousand dollars; and, at the top of the range, professional machines selling for tens and even hundreds of thousands of dollars. But there was nothing in-between. Finally, though, a few manufacturers began building machines in the $2000 to $5000 range – allowing our company to join in on the 3D revolution. Peeling back the layers Let me walk you through the various factors that come into play when it comes to the process of additive manufacturing and its various components and tools. CRAIG MILLER is a principal shareholder in Las Vegas-based Pictographics, ( where he is also director of military and law-enforcement projects, the company’s defense-contracting division. 12 THE BIG PICTURE JUNE/JULY 2013 Build envelope: Most of the hobbyist 3D printers are incapable of building an object beyond five or six inches in any dimension; but we felt that we needed something that could create on a larger scale. So we considered two different prosumer machines: the MakerBot Replicator 2, with a build envelope of 11.22 x 6 x 6.12 inches, and the Cubify CubeX, with a build envelope of 10.82 x 10.43 x 9.49 inches (basically the size of a basketball). We ended up choosing the CubeX because of its bigger build envelope and because the other machine can only work with one type of build material (more on this later). Resolution: Of the two machines we considered, the Replicator 2 can print to a layer height of 100 microns. The CubeX can only go as fine as 125 microns, but it has options for 250- and 500-micron-layer heights. Layer thickness determines how smooth and finished a final piece looks for 3D printing; too low a resolution and the thing looks like it’s made from a stack of angel-hair pasta. So, visually, the higher resolution (lower number) is better, but the lower resolutions will result in more speed. Speed: We recently built one part that took about 20 hours to finish at the highest resolution of 125 microns; it measured 9-inches tall by about 3-inches square. The same piece took four hours at 500 microns. Since the goal of building the part was for fit and functionality – cosmetics played no role – the lower resolution was just fine. We also printed a prototype of a small lens for use in LED lights, and we were able to create it in less than 30 minutes; this was a prototype to test for size and fit before it went to the plastics company for final manufacturing. Build material: With additive manufacturing, you’re taking spools of plastic fi lament and running them through a heated extruder, which make the solid plastic fi lament a viscous molten liquid. The extruder is on an X-Y-Z axis and it extrudes the plastic in a pattern reminiscent of cake decorating. The plastic cools and hardens and, voilà, you’ve created a plastic object. Our machine is limited to two common plastics: ABS and PLA (some machines cannot handle both plastics, while very high-end machines can print to 10 different >40

Table of Contents for the Digital Edition of The Big Picture - June/July 2013

The Big Picture - June/July 2013
Up Front
Inside Output
Flatbeds & Hybrids 2013 Report
Establishing a ‘Green’ Identity
Give Your Shop an Edge with Cutters & Routers
Technology Spotlight: ISA Expo

The Big Picture - June/July 2013