Talk Composites - The Forum for Advanced Composites

Wrinkles when vacuum-bagging :(

http://www.talkcomposites.com/Topic869.aspx

By brummelisa - 2/27/2012 6:36:29 PM

Hi,

I just made a toptube on a bike-frame. The tube was made from a plug that I vacuum-bagged.

I noticed that I have got a couple of "bumps" that I wonder how I can remove and to prevent for happening next time.

Can I just sand it off (I will add several layers on top of it)?

I wrapped the CF in two layers and was very careful that I didn't had any wrinkles. I used peel-ply and breather.

My concern is how can I assure not to have wrinkles when I'm vacuum-bagging? I mean when the vacuum is applied I don't have super-control if the CF wrinkles (since I can't see it through the breather).

Should I only wrap one layer at a time? (I intend to wrap 6-10 layers depending on which part I'm making.

Note, that I don't use a mold, but a plug and you can see the wrinkles in the attachment

/ Marcus
By Zorongo - 12/16/2013 8:57:44 AM

Time ago I did any composite tube trials.

The problem is that before applying vcuum, you have a certain thickness and outer diameter without any wrinkle. OK. BUT when applying vacuum and consolidating the cloths, the thickness and so the outer diameter, will decrease. Then you´ll have a cloth excess that under vacuum will end creating a wrinkle.

This will be worst when more plyes compacted.

Lately I've done a few tubes with shrink tape with nice results. Easy, cheap and flexible process for a "not highly stressed part".