Week 15 Wildcard Week

Assignment

Design and produce something with a digital fabrication process (incorporating computer-aided design and manufacturing) not covered in another assignment, documenting the requirements that your assignment meets, and including everything necessary to reproduce it.

What I did

I tried composites, so that I can utilize FRP for a casing of my final project.

1. Designing a mold

I need 120 x 120 x 50 (mm) box for the casing. My idea was that to create a box with 3D printer, and create a kind of roof with laser cutter. But FRP seems nice and strong against rain and sunshine.

This time I prepared below design with solid works. I made it simple as this was the first trial.

And 3D printed the mold (solid works file)

2. Cotton x Plaster with resin

• Our instructor tried this and seemed easy and I thought it was good for first composite trial.

Making process

1. Preparation of plaster
   • Mix the plaster powder and water (42ml of water for 100g of the powder)
   • Keep mixing for 3 minutes
     

2. Soaking the fiber in plaster liquid
   

3. Put the fiber on the mold
   
   

4. Put it in a bag and vacuum with a hand vacuumer
5. Vacuum done
6. Curing complete The plaster was not spread. Looks not beautiful
   
   Corner
   I should not have folded at the bottom, this seems difficult to remove.
8. Removing the mold
9. Actually the composite was not hard, so I managed to remove it.
   
   
10. Not hard.

1. Thoughts and feelings
2. The result was not good, the reason could be as follows;
   • Plaster liquid was too thick to soak through. But if I added water, the result would be softer. For this point, chemical liquid for polyester should be better.
   • I did not have clear way to fold the fiber onto the mold, especially bottom side I must fold the fiber outer side.
   • To use plaster as matrix, a cotton fabric was not thick enough. If I used thicker fabric it would be better.
   • At least it is possible to use as a dish

3. Fiberglass x Polyester

• Based on the first trial of composite with plaster, next I tried FRP for the casing.

Making process

1. Preparation
   • Mix the styrene liquid and curing liquid (100:1)
   • Well mixed
     

2. Cut the fiber glass

   • When I cut fiber glass, I must put on gloves and a mask. The reasoning I refer from below link "Direct contact with fiberglass or breathing airborne dust containing fiberglass may irritate the skin, eyes, nose, and throat." Washington state DOH
   • This time I cut it with scissors, but it is not good for 2 reasons. 1st as raised above, cutting with scissors may create tiny fibers. 2nd, very difficult to precise cut due to the structure of fiber glass.
   • I should have used cutter especially round blade looks good to cut fiber material.
     
     
   • I should have used cutter especially round blade looks good to cut fiber material.
   • If I cut it with machine tool, this site would be of help.

3. Put the fiber on the mold in a bag and vacuum with a hand vacuumer
   

   • Vacuum done
   • Glassfiber displaced
     
   • Curing complete
     
     

4. Removing the mold

   • I could not remove it.

5. Thoughts and feelings

• This was a failure. The reasoning seems as follows;
  • I could not keep the glassfiber shape when I put it into the vacuum bag. This caused displaced fiber as a result.
  • I could not remove from the mold because I did not make the mold's surface smooth. I must have did more sanding.
  • At least good thing was the shell was hard, even if it looks thin.
  • If I made the mold softer material like silicon, it would be easier to remove.
  • All in all it ended a mess, but I learned the important point of composites. The preparation of mold surface and vacuum bag must be better for next time.