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Box section manufacturing

http://www.talkcomposites.com/Topic34975.aspx

By Zeyad Gamal - 3/2/2020 10:53:13 AM

We are currently trying to manufacture a carbon fiber spar for a UAV.

We want to make it a square box section 16mmx16mm and a length of 2 meters, using hand-layup and then vacuum bagging.

We are planning to wrap the fiber around a square box section (wood, steel or aluminum hollow section), and try to pull it out after curing.

We tried foam, but because the dimensions are small, the foam couldn't handle the vacuum pressure. With aluminum sections we failed to extract the part, so, we tried wrapping the aluminum section with vacuum bagging film and adding release agent. That barely worked, but we are yet to try it on a 2m long part.

What's your experience manufacturing box sections? we have no access to specific machines to help us and its not possible to import ready-made ones so we are stuck with hand-layup and vacuum bagging.

We are ok with the resultant surface finish produced by the vacuum bag, we are more concerned about the success of the process.
By Buchado - 3/2/2020 10:50:43 PM

Zeyad Gamal - 3/2/2020 10:36:33 PM
Buchado - 3/2/2020 3:45:08 PM
Zeyad Gamal - 3/2/2020 10:53:13 AM
We are currently trying to manufacture a carbon fiber spar for a UAV.

We want to make it a square box section 16mmx16mm and a length of 2 meters, using hand-layup and then vacuum bagging.

We are planning to wrap the fiber around a square box section (wood, steel or aluminum hollow section), and try to pull it out after curing.

We tried foam, but because the dimensions are small, the foam couldn't handle the vacuum pressure. With aluminum sections we failed to extract the part, so, we tried wrapping the aluminum section with vacuum bagging film and adding release agent. That barely worked, but we are yet to try it on a 2m long part.

What's your experience manufacturing box sections? we have no access to specific machines to help us and its not possible to import ready-made ones so we are stuck with hand-layup and vacuum bagging.

We are ok with the resultant surface finish produced by the vacuum bag, we are more concerned about the success of the process.
Did you use demolding wax prior to the release agent?

It's usually better to apply demolding wax 5 to 7 times before using the release agent.
Apply the wax, remove it, apply the wax, remove, and so on, polishing the part.
After the wax, you use the release agent.
We are using a demolding release agent called Axson 841, i believed it should produce same results as normal wax

Like I said, you'll get better results using the wax AND the release agent.