Composites

Assignment

  • Read the material safety data sheet (MSDS) and technical data sheet (TDS) for the resins that you're using
  • Design and make a 3D mould (~ft2 /30x30cm), and produce a fibre composite part in it

What should be done

  • Shown how you made your mould and created the composite
  • Described problems and how you fixed them
  • Included your design files and ‘hero shot’ photos of the mould and the final part
  • Read and linked to the material safety data sheet (MSDS) and technical data sheet (TDS) for the resins that you're using

Getting the epoxy

I bought epoxy from a local manufacturer CMB I searched for other manufacturers but couldn't find a company that provide epoxy for small scale clients and with enough technical resources available for their products.

I bought an epoxy called "Kemapoxy 150" along with its hardener.

I looked for its material safety data sheet (MSDS) and technical data sheet (TDS) but all I found was its technical datasheet.

It didn't say much about toxicity other than some safety precautions.

So accordingly, I used a table that is outdoors in the lab and tapped some plastic on top of the working area to control dripping.

Experimentations

I wanted to experiment with natural fibers so I wanted to test palm tree leafs.

In Egypt, palm trees are common and their leafs and they are used in rural areas in agriculture and products.

The leafs are used in an annual Christian religious festival called "Palm Sunday" . A lot of people uses them to create rings and crosses and other things.

So, I got some leaves from a friend of mine "Michael".

The leaves are the ones to the right that are dried put a bit and the ones on the left are their stems.

I cut away some of those leafs, and figured that I should cut them to pieces of smaller with and length.

I started weaving those pieces together.

The pieces was spreading apart as they were a bit stiff so I did what Michael advised me to do which is soak them in water for a day which I did and I'm waiting for them.

Test Coupon

The composite that I will make this week will be wet lay-up layers of gauzeand epoxy "Kemapoxy". So I wanted to create a test coupon first.

I started by mixing the epoxy and hardener.

I added the parts to two plastic cups which then I mixed into a melamine plate to withstand the exothermic reaction if it's too hot.

Accidentally instead of mixing 2 parts of the epoxy and 1 part of the hardener, I did the opposite which I discovered later after finishing.

I first put two layers of food wrapping plastic to separate the composite and to skin for the composite.

I got medical gauze which I believe is mostly made of cotton cut out 3 layers. I added 5 more layers on the process as I had excess epoxy mix.

Afterwards, I flexed the excess two layers of the plastic wrapping from the bottom layer to cover the top.

I then cut out two pieces of plywood to be used to apply even pressure using clamps

But I noticed that the piece is too big to be compressed with only two clamps so I added another one at the bottom.

I left the coupon for two days but because of the wrong mix it didn't harden at all.

Mold Design

For the assignment I wanted to create a shovel that could be used in gardening.

I found a steel tube that I can use as a handle for the shovel.

So, In Inventor I started sketching the cut section for the shovel by creating a 18mm circle matching the tubes outer diameter.

Then continued drawing the rest of the cut section and extruding it.

Created a sketch on the front surfaced and closed the gap then extruded it to create a cap for the handle.

On the top surface, created a new sketch and drew 2 rectangles on either sided and extruded them to create a groove.

Added some fillets.

To create a tapered end for the shovel, I created a new work plane offseted from the front surface, created a small rectangle on it and created a loft.

To create the mold, I made a rectangular sketch at the top surface and extruded it downward with a "cut" operation.

Then to remove extra solids, I created more cut extrusions.

Then I found that there is no room for the handle this way, so I edited its extrusion to have a groove at the free end.

Toolpath generation

After setting up the CAM job, I added a "Facing" operation to smooth up the work area.

Then to clear the materials, I then added an "Adaptive" operation.

Then to mill the sloped surfaces, I added two "Parallel" operations

I then exported th .ngc file to use it in the machine.

Milling

Before milling the mold, I milled 4 test jobs .

Then, loaded the file which began the facing operation.

I noticed that the job might get outside the working piece so I reseted the Y home a bit lower and restarted the job.

Wet Lay-up

I applied the food wrapping plastic on the mold as skinning layer.

Then I cut pieces of gauze according to the width of the mold.

Then mixed up the 2:1 ratios of the epoxy and hardener and mixed them up.

I then added two layers of the gauze in a criss-cross manner and put the metal tube.

Then, added another two layers of gauze then food plastic.

Vacuum-bagging

I bought a vacuum-bag used for cloths storage which was quite big and sufficient for the job.

Then I added the mold into the bag and used the vacuum cleaner to remove the air and then sealed the bag using the cap included.

I left the mold for about 8 hours; As it completely hardened I removed it from the bags and removed the skin layers.

Them using the circular saw, I removed the excessive parts and gave it a go.

Files