davidtown
I would not mess with a bladder, they do work ok, making/machining a solid core would most likely be easier to work with, and could be accuracy fitted to the face of the mold ( open end ) for alignment
Good day everyone!!
New member and new to mold making.
I am attempting to make a two part mold used for making a composite (carbon fiber) part similar to an airplane wing. One requirement is the part needs to remain hollow. Thinking I can use the two part mold, a pressurized bladder, prepreg CF and a heated platen to make my part.
This link is basically the process I plan to use. Build-to-print: Done better : CompositesWorld
The part is not an actual wing but very close and not used for flying. Picture of the mold I am wanting to replicate is supposed to be attached to this thread.
My questions for everyone here is:
1. If my finished part is 5/8'' thick at the thickest point, how thick should my stock aluminum be? 2-3x the thickness of the max milled thickness? 3 x .625''= 1.875'' but thinner aluminum = cheaper mold for me.
2. How far from the edges of my stock be to the edge of my milled part? I was gonna use 2'' from all areas but don't know. Just guessing.
3. Assuming I need to use 6061 aluminum. Correct?
4. Best bladder material? I have researched this extensively and still haven't come up with great ideas. Any ideas would be BIGGLEY appreciated.
5. PSI the bladder is inflated to? Thinking 80psi. Thought I read that somewhere else.
About me...I have the Laguna IQ cnc machine with VCarve Pro for CAM and Rhino 5 for CAD.
Be well,
Dave
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davidtown
I would not mess with a bladder, they do work ok, making/machining a solid core would most likely be easier to work with, and could be accuracy fitted to the face of the mold ( open end ) for alignment
Mactec54
In that article, they speak of a silicone rubber bladder. I don't know of any other flexible material that would withstand the temperatures required by that process. But if, as was suggested above, you go to a room-temperature process, then a lot of other materials become feasible, including fiberglass molds instead of aluminum ones.
[FONT=Verdana]Andrew Werby[/FONT]
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In a closed mold you can use a "silicon intensifier". It is a solid cast piece of silicone. It expands against the mold walls when heated. The silicon "bladder" you are thinking of may be a vacuum bag. I have never used a process that inflated a bag inside a mold so can't offer advice on that.
I would make two molds
1. for the "dis-solvable" core for the Inner mold line, pour and cure core.
Wrap and trim for next mold.
2. final mold for pre-preg composite and the cooking process.
3. dissolve after cooking.
I did a dry load, foam / cloth RTM wing while in hi-tech land.
done this easily, and can elaborate
Been doing this too long