COMPOSITES

This week we have to design a mold and make a composite part. We are given strict instructions not to use carbon fibre and glass fibre in view of its potential health hazard. The Composite lab in SP has all the necessary safety equipment for the proccesing of carbon and glass fibres. However our team is gonna use to recommend burlap as we have never used that before to make composite parts. Curiousity brings us to new grounds.

First, in the creation of our mold. I used Blue Modeling foam that is actually XPS(extruded Polystyrene) more info about the material can be found at http://www.dctech.com.au/modelling-foam/ Although I would think aluminium or some rigid structure may be a better choice. But let's see...

I decided to make one of the panels of the astromech's head. it has an emboss on it in the centre for better structural strength (although it does not make much of a difference really :P) The 3D design was done on inventor and the mold was machined on the Roland MDX-540. I would be using the closed mold technique while my other teammates are trying out the vacuum mold method.

The 3D CAD files and Fabmodule .rml files can be downloaded here

https://www.dropbox.com/sh/3rlc8ldes2mbjr0/AAD37E8W6uzoAvrcIxWBt382a?dl=0

or

local archive

 
Machined Foam Mold Mold release wax Waxed mold.
After waxing the mold I prepared 3 layers of burlap. I cut them in different fibre orientation text book style :). The resin was then mixed and poured over the burlap. We did not get hold of the SAP100, so we used what was available in the Composite lab. The resin was mixed in a semi exhaust fume workstation. We layered the resin under an exhaust hood too.
Fibre Orientation Resin layered on Burlap Exhaust Hood
Next I clamped my mold and went off for the day. I returned the next day to open the mold and the surface finish was not the best. The Mold was destroyed in the process and the finished part has got a thin layer of blue foam attached to it. Secondary process is required to dremmel off the surface and probably have a layer of epoxy/paint over it.
F-clamp and a pressure plate Broken Mold Yucky Surface.
Dremmel ready for work coat of epoxy resin layer of blue paint gloss

My buddies had better luck. They were trying out the vacuum bag process. There were several layers that aided in the easy mold realease. In addidtion they had a lovely Research assistant to help them :) Their surface finish was a whole lot better than mine too :P
     
The Composite lab has got some interesting projects displayed too. They worked with short carbon fibers and made some interesting parts too, like a foam encased carbon fibre aerofoil. A good source of inspiration for future projects.
Suspension system using short carbon fibre Carbon fiber Hull of a model boat Encased Aerofoil