Wednesday, June 24, 2015

3D Printing: It's Strengths and Weaknesses

3D printing has been in the news a lot, lately. I just read an article about a 3D printed car made by Local Motors. In short, the article talks about a 700 horsepower engine in a carbon fiber, 3D printed car. They boast that the car is lighter than any other car out there, which I'm sure it is. The car was apparently also ridiculously expensive to manufacture. On top of that, 3D printing is a very slow and long process.

I am part of several science and tech clubs in my area, and I had the fortune to attend a presentation on 3D printing. The guy that gave the presentation had a small hobby unit. He talked about the different programs that he uses to run it (most of which are free), the process that he went through to create the model for the printer to recreate, and the steps he went through afterwards when the piece was finished. At the end of the presentation, he printed a 1" in diameter sphere while we all watched. I got a front and center view. The time it took to make the simple, little sphere was ~20 minutes.

In the presentation, the presenter also talked about the properties of 3D printed objects. You can use a wide variety of materials to print whatever your heart desires; some materials are studier than others. No matter what material you use, though, all the things that you could print still have a compromised structural integrity. If you test an object one way, it will be solid and sturdy. Rotate that object about 90 degrees, though, and it fractures and splits easily. Since the 3D printer prints in layers, it give the object a "grain," similar to the grain you get in wood. The object is strong perpendicular to the grain, but parallel to the grain it's weak.

The 3D printer car concept concerns me for this reason. I haven't seen any diagrams for how the car was created, so I don't know if they accounted for that or not in the design. Something else that concerns me about the car is the material that they used: carbon fiber. Carbon fiber is pretty strong and light when compared to steel or a similar nature. But carbon fiber shatters and fractures where steel will just bend. It's possible that they've accounted for that in the design of the car, which would be my hope.

3D printing isn't good for everything. It has a lot of flaws. But there is one thing that I think it is good for: organ printing. There have been a lot of 3D printed organ experiments, ranging from a thyroid gland (made in the Russian laboratory 3D Bioprinting Solutions) to 'dead' hearts.

There are a lot of uses for 3D printing, but I suspect that making cars won't be among the uses that last into the future.

1 comment:

  1. A couple of higher-tech metal applications of 3D printing:

    Using 6-axis welding robots to 3D print a steel bridge in place:

    3D printing copper rocket engines with the goal to make manufacturing 10x faster and 50% cheaper:

    Note that in metal 3D printing can be significantly faster and more accurate then, say, stamping a bazillion pieces of metal, stacking and sintering them together - the current high-end rocket nozzle tech. (My source: a conversation about 2 years ago with a rocket scientist who was actively at work on a nozzle design at that time.)

    The layering problem can be rectified if each layer is thin enough: then you simply get a sintered single-piece part. Where I work we make alloys that would, if fully melted, separate into the various parts: we take various metal powders (copper, iron, &c.) put them all on a mold under a ton or two of compressive force, apply heat using an inductive furnace for a specific period of time, then cool at a specific rate. When done you have an "impossible" alloy: one that combines the properties of many different metals in a way that would never work if you tried to melt them entirely.