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Car 4 Battery Pack Manufacturing & Considerations for Car 5

Box

  • DXFs were created for the sides and bottom of the box to get an idea of how big we needed to make the sandwich panels and if we had core (divinycell was chosen because of availability) that could fit the parts we wanted to cut out.
  • 0.25" thick core was chosen over the 0.125" to be on the safer side.
  • After measuring out what could theoretically fit on the core available, 2 slightly oversized sheets of fiberglass weave were cut out.
    Prepping the work surface
  • A large sheet of polycarbonate was cleaned with alcohol and wiped down.
  • Then waxed smooth and let dry (this is to not allow the glass to cure and stick onto the polycarb
    Layup
  • One layer of glass placed down onto the polycarb and wetted out with the mix of resin and hardener.
  • Squeegees were used to evenly spread the resin all over and into the fiberglass.
  • The next layer was put on top and then wetted out similarly.
    Curing
  • We had two methods for this next step:
    1. Peel ply then some large plate (could be wood even) to distribute the weight
    2. Another clean waxed piece of polycarb 
  • Either way, a large weight was placed over it, making sure to get any air bubble out before.
    • This is not the best method for this, that would be vacuum bagging with peel ply and breather (ask aero or structures)
  • Then it was left for 24-48 hours to fully cure.
    Other Side
  • The steps above were repeated for the other laminate 
  • Then one laminate was covered in a thin film of ea 9430 using squeegees and the core was placed onto it and pushed down for full contact and to remove any air bubbles. Then the next laminate was similarly coated and placed, adhesive side down, onto the core and any air bubbles were pushed out. 
  • Then it was weighed down in a similar manner to when the laminate were curing. 
    Water Jet
  • After the panel was fully cured we water jet at MAE C and let the cut out parts and let fully dry at the lowest temperature a home oven could go for 15 minutes. 

 

 

Car 5 Considerations 

  • The biggest obstacle when manufacturing was the time it took to 3D print the modules and rails with rapid proto, we even sent it to jeff’s lab as well but in the future, it might be worth finding other manufacturing methods. Considering the size and the importance of the modules to the functionality of the pack, manufacturing using a non-prototyping method and material. One idea is to CNC the modules out of Delrin or some other hard plastic to avoid issues of bending we had with the 3D printed ASA. This would also introduce another manufacturing technique that members would greatly benefit from gaining experience in.
  • Another manufacturing consideration is the time it took to make the fiberglass sandwich panels for the box. 
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