Multi-Material Experiments TPU / PLA

Multi-Material Experiments TPU / PLA

I’ve been experimenting with multi-material prints latley. This time i am not trying to just use different filament colors, but i am trying to combine different properties of materials in a single print.
PLA is probably the most commonly used filament type as it is easy to print.
TPU is a bit more difficult to print as it is a flexible material, but for some parts the flexibility is what you need. In the past i printed lots of parts for quadcopters using TPU.
By combining the 2 materials you can open a whole world of new possibilities, but there is a slight problem. TPU and PLA will not bond very good to each other. initially there is some bond when printing the materials on top of each other, but quickly if you apply some slight force, the materials start spearating again which makes printing useful parts in thiscombination quite difficult.
i#ve been experimenting a bit and think that i came up with a solution for this problem. The trick is to use an “interface section” which adds a mechanical bond instead of just relying on “melting” the parts to each other. The mechanical interface can than act similar to those “rip-stop” textiles where an structure is used to stop textiles from being torn..
To create this interface section i created a pattern where stripes of PLA and TPU will be printed next to each other in a grid pattern. then in the next layer the whole pattern will be rotated by 90 degree, creating a 3D structure where the 2 materials are kind of “woven” into each other.

I did a quick design in openscad and added this interface pattern for 3 layers.
this is how the first 5 layers of that print look in Slic3r:

I printed it using my multi color profile on a standard MK3 (without MMU) The print required a total of only 3 manual filament changes.
Here is the finished print:

In case you want to play around with it ,i uploaded the stl’s and a 3mf file here:
https://www.prusaprinters.org/prints/11202-multi-material-hinged-roll-up-box-experiment-tpu-p
 

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