mikejkd

I have made auto parts in FG but am wondering why what I did will not work for more things. I made a mold put the fabric in and but a bag over it that had tubing attached so when the vacuum was pulled I put the resin in through them and clamped the tubes closed when I was done. Is this what you guys are doing? I understand that people are making there own bags that are the same shape as the part out of some paintable silicone but can not find more info on it. Are you guys making silicone bags?

Thanks
Mike

buttuh

What you did sounds like vacuum infusion which is kind of new to me. I have not tried doing that yet but have seen positive feedbacks on it.

As far as the conventional vacuum bagging goes, you do a wet layup over the mold, place it in the bag and vacuum it. You can shut the hose off but you need to make sure that pressure level is maintained and there's no leak. Sounds to me like you place the dry fabric on the dry mold, vacuum it and then pour resin into the tube which is not what you're supposed to do.

If I misread your post, I apologize.

Evan

mikejkd

Thats exactly What I did. It was not the same tube as I pulled vacuum from thought I attached tubes in various locations. Why should you not do it this way? It worked perfect and it had no wrinkles because I could position everything first. What am I missing?

Thanks
Mike

buttuh

Ah so you were doing the infusion so I DID misread your post.

Conventionally you wet the fabric with resin, place it over the mold and set the fabric where and how you want it. The vacuum bag would then hold the fabric down while squeezing out excess resin to the breather ply until your part is cured.

I thought you were pouring resin into the same vacuum tube. But other than that your process works just fine.

As far as silicon bag, I have not heard anything about that. I just use the standard setup (bag, peel ply, breather ply, etc).

Evan

Jimbonk

Mike, Your method of "injecting" resin is interesting, but it must make parts a little on the heavy side. Most Airplane Guys become fanatical about using only enough resin to wet out the cloth/fiber. Once you get the cloth wet , it's amazing how much resin you can remove. Most people use the 50/50 standard, no more than 50% weight of resin to cloth as a goal.
Silicon bags are used in bagging epoxy prepreg parts that require Heat to cure. The Silicone will take a lot of heat and it will stretch a huge amount ,but the bags are a little "pricey" for modelers.

Jim B

buttuh

Actually Jim, I believe his method yields the best resin/fabric ratio. As long as you don't allow an unlimited amount of resin to be infused. I'll try to find a link with a more detailed explanation on the process.

aparchment

Here is some info for you on SCRIMP resin infusion molding (Seeman Composite Resin Infusion Molding Process)

http://www.tpicomp.com/technology/advantage.htm

This is a great technique. I work with several boat companies that use this process to fabricate lightweight hulls.

Antony

Mike James

I just read the SCRIMP info.

I wonder how critical the placement of the resin inlet ports is? Any engineer types have some info for us?

70%-30% cloth-to-resin ratio, with MORE strength... Very nice!

mikejkd

When I did it for the car pieces the resin traveled very far and I actually had to many opening in the bag. It was very easy and not that messy and that is why I was wondering why I have not heard of you guys doing it.

buttuh

I've heard about it a while back but too chicken to try it until I can see a demo of the entire process done.