Jul 1, 2016 | By Andre

When I was tasked to write about concrete business cards and how 3D printing can help make them happen the first thing that crossed my mind was “what?” But then as I started into the Instructables entry that dealt with the topic I was relieved by its opening: “Ever see those concrete busines cards online?” Ah, yes, the internet. Of course there is such a thing as concrete business cards so why shouldn’t an intructable be made to assist in the making of them?

The premise is to create a very thin concrete sheet that is strong enough to take a little bit of handling and flex without instantly shattering into pieces. To complete this task, Singapore based Instructables user UCN casted concrete directly into 3D printed moulds and a variety of 3D printed meshes to act as a reinforcement structure hidden within the card.

From a technical perspective, the moulds were printed on a standard FDM filament based 3D printer using PLA plastic. With overall card dimensions of 90x50x2.5mm and with little concern about print resolution he went with 0.5mm layer height and a 20% fill. From what I’m seeing, any number of combination of print settings would have produced similar workable results so it makes sense to save a bit of time with a low layer height.

The meshes themselves were done at the same setting. In this case, it’s possible that the thicker layer height would increase the strength of the mesh vs. a higher resolution (more layers could mean inconsistency in fusing plastic and thus a weaker overall structure, but in all likelihood any layer height would have sufficed from a 3D print perspective.

Once the printed parts were complete he was ready to move into card production. By using a consistent 4:3 cement to water ratio and a silicone sprayed 3D printed mould, he poured the concrete and let it sit overnight (while making sure the surface was flush and smooth).

The next day, he was able to bend the PLA plastic mould out and thanks to the silicone lubricant it separated without too much trouble.

After settling another day, experiments on load testing commenced. Almost immediately, and without much surprise, the pure concrete sample card broke with a load of just 160g. The version with a diagonal 3D printed mesh on the other hand didn’t begin to crumble and bend until 595g. A third effort with a square mesh buckled at 670g but it was the fourth attempt that began to yield the results he was after.

Using the same card dimensions as before, but this time the design file had a frame incorporated right in, the fail-weight averaged out at 1680g. An entire KG more than the second most successful effort! The problem, unfortunately is that the frame showed through the card and lacked the seamless structure he was after.

As the Instructables continues to explain his project, he suggests ABS might be a better alternative than PLA and that non-3D printed meshes (such as mosquito netting) might yield similar findings. And while the end-result of his experimentation might seem impractical to some. He hopes that what is learned during this process can be translated into other projects such as RC building. In the end, trying new things and experimenting with failure is never a bad thing, and at the very least he can impress his friends with his very own concrete business cards.

 

 

Posted in 3D Printing Application

 

 

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Don S wrote at 7/9/2016 7:51:01 PM:

Nick is spot on ...first thing I noticed was too much water, his mix suggestions would yield an end product twice as durable, but likely way beyond what was achieved in a shorter curing cycle....But was a neat experiment

Nick Gencarelle wrote at 7/1/2016 8:29:31 PM:

Too much water and he could try a geopolymer or UHPC version with a basalt scrim.



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