3D Printing: Putting the 'Additive' in Manufacturing

Unless you’ve been sleeping under a rock, you’ve probably heard a lot of recent news about 3D printing – also referred to as rapid prototyping or additive manufacturing. In fact, if you believe the hype, even sliced bread has now taken a back seat to 3D printing. Soon, you’ll no longer have to go to the store to buy the widget you need; instead, you’ll be able to simply print it with that 3D printer sitting on your kitchen counter next to the coffee maker. Some pundits are calling this capability a spark for the next industrial revolution.

So you’re also likely familiar with the basic concept of 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 filaments) 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 what I like to refer to as the first “prosumer” 3D printers. Until recently, only two disparate categories of printers were available: On one hand, there were hobbyist models and kits that sold for a few hundred to just over a thousand dollars; at the top of the range, there were professional machines that sold for tens and even hundreds of thousands of dollars. But there was nothing in-between. Finally, though, a few manufacturers began building some machines that were priced in the $2000 to $5000 range – and that price point allowed our company to join in on the 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.

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.

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 materials). ABS is what the bumper covers on our cars are made out of; it’s outdoor-durable and works reasonably well for most applications. The downside of ABS: If you’re printing on a desk in an office shared with people, the smell can be offensive. PLA or Polylactic acid, on the other hand, is more environmentally friendly – made from plant starch; it’s even biodegradable. I can’t detect any smell associated with a PLA build. Because only the two types of plastics are available, I’m limited to the kinds of things I can make. For instance, neither ABS nor PLA are food certified.

Both of these plastics come in a variety of colors; there are translucent materials, but no clear as of yet. Bundled software allows you to print in multiple colors, depending upon the printer model. For our system, by the way, the plastics come in cartridges – similar to ink cartridges; these are basically plug-and-play. (You can also buy third-party spools of ABS and PLA filament for about a third of the cartridge cost.)

Tensile strength: Keep in mind that additive manufacturing involves extruding a plastic “wire,” like a thick monofilament line, to create a layered object. The strength of the build relies on how well the fusion between the various layers sticks. This is the weak point in every build. In the two non-fused dimensions, the product is amazingly strong; but in the vertical or z-axis of a build, it’s possible to snap the model by hand (although this has not been a problem in any of our builds to date).

Becoming self-sufficient
The main reason we bought a 3D printer was to do in-house prototyping. To accomplish this, however, we had to have in-shop: one, a CAD software program; and, two, a designer who could become proficient in 3D CAD.

We chose a very powerful, yet intuitive object-oriented CAD program called SpaceClaim from the company of the same name. The software was about as expensive as the printer itself, but we have been very happy with it. And, I’ve since been reading reviews of excellent, less-expensive CAD software packages, if you are looking to manage your costs on this end. Two that have caught my eye are McNeel’s Rhinoceros and Cheetah’s Cheetah3D; both of these seem to be powerful and intuitive, and their price point is in the hundreds of dollars.

Tom, one of our designers, had experience with AutoDesk’s 3ds Studio Max modeling and animation software, so we asked him to spend work hours going over the tutorials in SpaceClaim. It took a few weeks, but in that time he was able to teach himself to design in 3D CAD. So we became self-sufficient in additive manufacturing. As it turned out, we now have a lot more need for designs than we initially anticipated, so we have also retained a freelance designer to augment Tom’s work. This has helped us move projects along at an amazing speed.

The future of exponential returns
We were able to justify the ROI of developing 3D capability based solely on our own internal needs. Just recently, though, we did our first 3D job for a client. We don’t anticipate becoming a “3D service provider” per se, and we don’t think 3D printing will ever become a standalone profit center for us. But a modest income from these sorts of print-for-pay jobs will help reduce the overall cost of owning the printer.

Looking back, I’m glad we took the 3D plunge. In all, we have invested less than $10,000 for the equipment, software, and labor. As a result, we now have an incredible capability that has helped us develop products that I’m confident will provide exponential returns. Plus, this experience has put us in a good position to evaluate the future trends and needs in additive manufacturing. If the market develops for us to sell 3D design and print as a profitable enterprise, we won’t hesitate to make the capital investment in more high-end equipment.