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3D Printing: Putting the 'Additive' in Manufacturing

(June 2013) posted on Thu Jun 20, 2013

Can you justify investing in 3D capability?

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By Craig Miller

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. Yesterday, we 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 filament and running them through a heated extruder, which make the solid plastic filament 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.