Design and make a 3D mold (~ft2), and produce a fiber composite part in it.
DESIGN
For this assignmend i have designed a 3d mold that has an origami form.
The steps followed were:
//DESIGN MOLD
//MILLING MOLD
/Fabricate mold from high density foam using milling machine.
/Software:
//Partworks 2d and 3d, design software
//Shopbot 3, control software
/Tools:
//ShopBot 3 axis CNC router
//Bits 12mm and 3mm
//Drill
//Screws
Shopbot TUTORIAL
/Material:
//high density foam
// DO THE COMPOSITE MATERIAL
/Place a protective fabric layer (peelply) over mold(used to allow separation)
/Place a layer of canvas was cut to shape and placed over peelply sheet.
/Position wood veneer pieces in place (shapes to fit the origami “folds” were cut using a laser cutter) using epoxy cement to keep the two layers together(Mixing ratio 2 parts epoxy, 1 part hardener).
/Place a protective peelply textile
/Place a breather textile(allows all the air to be absorbed by the compressor)
/Place into a vacuum bag
/Allow to cure for six hours.
A protective fabric layer (peelply) was put over the mold and over the composite layers to allow for separation after drying. A second composite was also made using a plexiglass spacer (made with laser cutter) to keep the pieces in position
VACUUM BAGGING
Tips:
/The peelply separation fabric did not work well in my case and it was difficult to separate the final product from the mold.
/Be careful in placing the epoxy to ensure that it goes where it is needed and not to get the epoxy where it does not belong. In my case, more epoxy was needed in some locations (example: corners) but also slipped into the gaps between the wood veneer pieces, making fabric folding difficult.
/The slope of the mold caused some pieces to slip. The composite where no mold was used but a spacer was used seemed to work better. Also, when the vacuum was applied, it had the tendency to push the parts of the composite that were higher, down along the slope.
/It is best that the vacuum bag is in good contact with all pieces of the composite surface. When there are gaps or uneven surfaces, the top part of the bag has a tendency to “bridge” and does not apply even pressure everywhere.
/Also be careful when placing the mold in the vacuum bag to protect the bag and the mold with with peelply. What the epoxy comes into contact with is very difficult to remove and trying to remove it may destroy the bag or the mold or both.
Mold: