1. Design and make a 3D mold (~ft2), and produce a fiber composite part in it.
2. Re done the assignment with a wooden mold
For composite week I wanted to explore and make a glass fiber composite on a foam sheet mold. The first step was to design the mold in rhino. The design of the mold is according to the dimension of arm that I am working on for the final project. The 6 axis arm will have all the structure members into it and this kind of glass fiber will make an external layer to the arm so all the structure and wires are hidden and it looks neat. Casting from glass fiber is easy and also the part that is made is easy to handle and it is light in weight as it only creates the outer surface of the mold. These are the few images of the mold in rhino.
Once the mold is ready I have taken it into the shop bot for the milling process. The software we use is part works 3d for our shop bot. Once the file is loaded in the computer the .obj file is taken into Part works 3d and the Roughing tool-path is assigned. Once the roughing tool path is done the finishing and cutting tool path are assigned. Here are some of the screen-shots of the process.
Once all the tool path is done its ready to mill on the shop bot. The first roughing tool works fast and removes the material and gives the basic form.
After roughing tool path the finishing tool path works for 45 minutes smoothing the surface of the mold.
After all the 3 tool path the final outcome is like this
Once the mold is done It is ready for the casting now.
There is one drawback of the foam sheet casting. I will be working on glass fiber and the casting through glass fiber takes on heat while it starts settling up.
There was a fear on damaging the mold but I wanted to try out the result on foam sheet.
Once the mold is ready I finished the mold with the wax/ that is to protect the mold for getting it damaged.
These is why I layered the foam sheet with two layer of wax.
Foam sheet covered with wax so there is no damage to the surface of the foam sheet
Foam sheet not covered with wax so there is damage to the surface of the foam sheet because of the heat gain
modeling clay/ wax
The wax layer is applied to the mold to prevent the damage to the mold. Once the wax is applied to the mold than the mold is placed on floor and the modeling clay is used for the finishing of the clay.
The 2 openings of the mold is covered with the modeling clay to prevent layering on the final mold.
First coat of the epoxy coat is applied to the wax coated mold and the on the modeling clay. Once the first coat on the mold is done by the epoxy mixture and it is applied to the modeling clay too.
The glass fiber resign is kept on the mold. The process should be fast. Once the first coat is applied the next coat will be done before the layering of glass fiber is done.
Glass fiber is kept on the mold within 2 minutes.
All the process of molding and casting should be done in 10 minutes of the process.
Once the epoxy is applied it starts getting heated.
Once the temperature of the mold goes down it is removed from the foam sheet and the surfaces are finished.
After the second layer is applied to the mold It is ready to remove from the main mold.
As I used the foam there was the damage to the foam as the heat absorbed the mold while casting.
It is dipped in water to decrease the temperature of the mold for removing the casted piece.
Once the mold is finished It look like this and the mold that I used for casting will not be used again as it was damaged due to heat gain process in casting.
The mold was made of foam sheet so the casting of glass fiber actually destroyed the mold. So I wanted to make one more mold of the wooden block.
I am slightly changing the design as now I wanted to mill the wooden block and re make the piece.
The milling of the block started. Once again a journey began..
Once the milling is done now I did small finishing work with the sand paper.
AFTER milling I covered it with the plastic rap
After the process of covering the block I realized that its a wooden block that need not be covered and can do direct casting through the block.
2 cotes of wax is applied to the wooden mold and then the mixture of epoxy and silicon, nickel and marble powder is mixed and applied to the mold with the help of the brush.
I waited for some time to let the first layer dry after applying it to the mold. Once the mold is covered with the mixture of silicon and marble powder. Once it dried up now I kept glass fiber on top of the mold in the semi dried condition.
Once the glass fibers are kept and again a layer of silicon and nickel in applied on top of the glass fiber. So now the heating is on. The casted piece is now heated due to its chemical properties. I am waiting for the mold to cool down so I can remove the mold and see the result.