The challenge: composites. Due to this week's complexity, myself as well as another student, Victoria Bell, will partner and do a conjoining assignment to learn and understand these processes. Upon discussion, we decided to create a 2-part composite case that can hold a Mac laptop. The case will also house foam padding for extra protection. We started by using the specs of the computer to identify how we wanted the case to look. Because this will (essentially) be a 2-part mold, Victoria will produce the top of the case, and I will create the bottom. Insulated foam will be used as the core of our composite as well to provide a light weight.

In order to fully understand the compositing process, we decided to do a mock run-through of what it will be like to create a composite. So we took scrap pieces of foam and fabric and fully went through the molding procedure and established our own technique. During this trial, we discussed and worked on how to properly pre-preg the fabric, the layup of the fabric and the pattern for how the fabric should be cut out depending upon the shape of our composite. Once our coupon was fully cured, We saw that the ends of the fabric were raised and not flat onto the foam. I believe it was due to the fact that there was not enough resin pregged into the fabric, as well as how we tried to do our vacuum bagging. We also attempted to do creases in order to have the best sharp corners of our coupon.... Needless to say that didn't work out how we wanted so we are not doing creases for our actual mold.

mock2     mock1     crease     mock3

Because our concept seemed to be simple and straight forward, I started out my design by creating it in OpenSCAD just for 3D imaging to know what would potentially be the end effector. Once that step was complete, I recreated the file in Partworks to be milled on the ShopBot.

3d file     pw file

profile     pocket     Tool

Because my mold had included an insert, I needed to create a pocket (for my object to sit it) and a profile (for the object itself to be cut from the material). Because we were using foam rather than wood to be milled as our core, we used carpet tape to secure it to the bed (rather than nails or screws) so not to damage or tear it, an 1/2" straight bit and slowed down the machines' R.P.M. to 9000 from 14000 so that the material would not melt due to the extreme speed of the machine.

mill3     mill1     mill2

Once our parts were milled, we needed to design the fabric pattern that would be the layup into our composite. I used CorelDraw for this step so that the fabric would be cut precisely with the laser. It was brought to our attention that we needed an efficient way to cover the corners of our core; so Victoria hand-drew a small tab that I recreated in CorelDraw and was cut out with each of our patterned layers.

heroshot     corner     corner2

all parts   resin    pre-preg

vacuuming      clamping

heroshot


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