[WEEK14] Composites
0.Outline
What I made.>> Pot for small plant
In this assignment, I tried to make composite product using vacuum formed mold. It has the following reasons.
- The material used for vacuum form is easy to release without mold release agent.
- Vacuum formed mold can be bend, so it is easy to release from composite product after curing.
- The mold for vacuum form can be made with 3D printer. It is easy and rapid.
- All materials used for making mold is cheap and easily available.
I think this process is suitable for quickly making a composite material. So I wanted to challenge it.
STEP1: Making mold for vacuum form with 3D printer. STEP2: Making mold with vacuum form. STEP3: Pasting the composite using the mold.
1.Making mold
I tried to make a pot because I needed it. At first I made mold with 3D printer. After modeling with Fusion 360, I printed it.
Download
pot.iges: Download the file
2.Vacuum form
This is vacuum former in our lab.
How to use the vacuum former.
- Preheat for 2 minutes.
- Set 3D printed mold and fix to the platform with double sided tape.
- Set material. I used polystyrene sheet (1mm).
- Unfasten a platform stopper and press the mold against the material. If the suction power is weak, push up the platform by hand so that no gaps can be generated.
At last, Cut out unnecessary parts.
3.Making composite pot
Material
Fiber:linen fabric Matrix:Plaster with resin
MSDS
SDS of this material
MSDS for similar material (in English)
I Poured plaster little by little into water. The volume ratio is 1:1. After investing all the plaster, stir it.
After painting plaster on the mold, stick a fabric on it. And then, I impregnated plaster into fabric with a brush.
I put it into vacuum bag, and sucked the air with a vacuum cleaner.I took it out after 30 minutes.
In order to compare the difference in strength, I made two kinds of samples, 1-ply and 2-ply.
After curing, I cut unnecessary parts with scissors and nipper.
I compared strength of each samples. Of course, 2-ply are much stronger.But, even if 1-ply is enough to hold shape, it is enough.
Finally, I fixed two samples with glue to complete the pot.
4. Another product
4.1 Making 3D mold with CNC machine.
At first, I modeled 3D data of a mold with Fusion 360. I was going to make a dish.
I created nc data for milling using CAM function of Fusion 360. After rough cutting with "Pocket Crearing" command, finish with "Contour" command. I made each files separately.
Pocket Crearing
Contour
I started to mill with 6mm square endmill, but I had one problem. I didn't have the endmill with appropriate length. So as machining progresses, the chuck would hit the side wall.
Therefore, I stopped working before hitting and cut unnecessary area with a cutter. And then I restarted.
I could finish machining, but I took a mistake. I intended to create two machining data separately, but it was together. Therefore, after the first machining was finished, the second machining started. I planned to mill the contour with a 6 mm ball endmill, but it was done with the square end mill halfway. I exchanged the endmill and started from the beginning, but the mark of the square endmill remained. I modified the data, but I decided to use the mold as it is, because it became interesting design.
Download
dish.iges: Download the file
dish_pocket.nc: Download the file
dish_contour.nc: Download the file
4.2 Making composit product
I used the following Epoxy resin as a composit material.
GM-6600: Product information
I couldn't get MSDS of this product, so I searched for MSDS of similar items and got information.
The material to be impregnated was cotton.I decided impregnate two layers with a slight overlap.
At first, I affixed aluminum foil to the mold using spray glue.
I painted silicone as a release agent.
I mixed main agent and curing agent of epoxy resin in the following proportions.
Main agent: 110g Curing agent: 33g (Main:Curing=10:3)
The epoxy was impregnated in the first layer according to the mold, and then the same operation was done to the second layer.
Impregnation was complete.
And then, I did vacuum bagging.
After 20 hours, I removed the product from the mold.
It has enough strength as a dish, but aluminum foil remained. It may be because the amount of release agent painted was insufficient or the drying time of release agent was short.
It is possible to use as a dish.
