Recent advances in additive manufacturing has opened huge avenues for designers to focus its applications into different industries. Different ideas are being tried and tested [1], regarding incorporation of functionality of additive manufactured parts.
Over the past few weeks, we have ventured from wanting to design a biomedical device of sorts to going to simpler idea since our project idea of embedding electrical components into an FFF part is slightly more complex than initially imagined. Breaking any biomedical device into individual components and then putting them together during the print would require higher expertise. We have switched gears to design a wearable flashlight on a finger which will serve as a proof of concept so someone in the PEC can take it further if it’s deemed a worthy idea.
The first step was to test the idea itself. Few questions, we were looking answers for were,
- Will the printer and the print work if paused and resumed?
- How long can we pause the printing process?
- What would be the effect of embedding in delamination between layers?
- What all parameters need to be put into the part design to satisfy our requirement as well as printability of the part in an FFF printer?
Trial 1
We decided that we should first try to design a simple part to 3D print and “embed” paper into it to see how well the embedding process would work. The printing process was paused and then pieces of white printing papers were laid on top of the printed layers. Also, a stapler pin was put on top of the layer as shown on the figure 1.
Results:
The prints came out well. This validates the idea of embedding components during printing. Regarding delamination between layer, since paper separates out the attachment of the layers, this area would be the initiator of failure or breakage of the part. As seen in the figure 1, if the part contains slots or passages for the embedding of components, delamination between the layers could be avoided. Also, the tests showed that if the part is designed properly, the ‘print-pause-print’ strategy should work just fine.
Another area of concern is the size and orientation of the space to embed electronic components into the print. The minimum size of any feature in design should be large enough to keep it sturdy while the extruder passes over it. Also, the component sizing should be carefully incorporated in the part design so as not to exceed the slot space that could potentially cause delamination between successive layers.
Trial 2
After verifying our idea, we decided to design a few flashlights that could be worn on our fingers. These designs will have cutouts where different components and wirings will be embedded. Multiple designs were created in CAD systems and then printed for their feasibility.
Design1
Our first trial run of Design1 print failed because the printer head would bump into the part and cause it to be misaligned (ref. Figure 3). We tried printing with tough PLA and the more flexible TPU, which is more ideal for us given that we would like the flashlight to be worn on a finger and still allow for normal movement. TPU failed multiple times for the same reason as above, however, we were able to verify that TPU would be suitable for a wearable device given the part that managed to print before failure. We were able to get the tough PLA to work when slowing the print speed down (ref. Figure 4).
Design2
Cylindrical finger mount type Design 2 was also printed using TPU. The first trial failed because of significant overhanging part in the interior. The part was re-designed to provide self-supporting overhangs and printed with TPU. The printed part has been shown in figure 5.
Figure 5: Two prints for Design2, Failed (A), Successful (B)
Design3
A third type of design (Design3) is under print as this would provide more insights into what else needs to be considered before we finalize our design.
Based on these trial runs and results of print, we are working on finalizing our design and spending some more time over at the Makerspace in order to verify our project idea of embedding electrical components into an FFF part. We ordered a simple flashlight kit from Amazon that has fairly small components such that they wouldn’t need to have a huge cavity to put them in the part during the print.
The takeaway from this update is that for the goal of a support free, assembly free, digital manufacturing of an electronic device using additive manufacturing, a lot of time and effort needs to be put into part design and process design.
References:
[1] https://www.sculpteo.com/blog/2017/03/29/3d-printed-screw-threads-which-material-which-design/