18. Wildcard week¶

For this week, since we were free to explore anything we want, I decided to use laser machine to try and fuse plastics which can be used for soft robotics. On researching about this, I found at that this has been done before in fablabs earlier. Below are the reference pages I found.

http://archive.fabacademy.org/2018/labs/barcelona/students/javier-alboguijarro/week16.html

http://www.mit.edu/~calisch/fold/www/welding.html

Fusing Explorations¶

• I started by gathering all the waste plastics I could found around my Fablab to start experimenting.

• All I could find was a roll of transparent PVC (Cannot be used with laser) and sheet of LDPE which I could start expermenting with.

Fusing LDPE¶

• Since this material was recycled, it was wrinkled and hence I streched it and stuck 2 layers using a paper tape on a piece of mdf.

• These were the power setiings I tried and made lines to test on the sheets of LDPE.

• Though I could see the material had fused, the edges were burnt as seen. So I made these circular pouches in which I can fill water and test if it is water tight.

• I fixed the material in the same way as earlier using paper tape, and used the below power settings.

• The first observation after this was that the edges where the laser changed direction were burning. But otherwise it seemed okay so I decided to test these.

• The Power:7 Speed:100 had burnt through at certain points and hence it wasnt gonna work.

• The Power:7 Speed:150 also had open area where the laser had gone through and hence didnt fuse.

• The Power:7 Speed:200 however held the water pretty well inside without any leaks.

• The Power:7 Speed:250 didnt fuse properly and had visible leaks as well.

Fusing OHP sheets¶

• Next, I tried using OHP sheets which are relatively thicker than the LDPE I used earlier.

• But since OHP couldnt expand and hence it couldnt hold air or water in it.

Hence I tried using one layer of OHP and one layer of LDPE I used earlier.

• But that didnt work either since the settings I needed to melt and fuse OHP went through the LDPE material.

Fusing garbage bags.¶

• Next, I got new wrinkle free “garbage bags” (Could only get them in black) and tried similar settings with them. This material was even thinner than the LDPE I used earlier.

• Even the minimum power settings went through this material and hence I defocused the beam for the next experiment.

(Note : When I lowered the power below 7, there was no laser coming out of the machine hence I could not go below that)

• The end result was the same where the laser went through.

• The below table shows primary observations with the power settings for this week’s experiments.

Conclusion¶

• Only LDPE of certain thickness was the material that I could fuse using our machine.

• For laser fusing, the material had to be elastic and bendable and hence thicker materials like OHP sheet couldn’t fuse.

All files for this week can be downloaded from here.