Composite Part Stuck to a Mold
2

Question

Composite Part Stuck to a Mold

Cisnerjo (Aerospace)

(OP)

20 May 23 15:10

Hello everyone,
I have a problem with a part, it got stuck to the mold tool, there were 17 cycles already performed on it (applying 2 coats of release each time) so it started to build some resin on the surface, so I lightly buffed it down with a scotch brite and re-apply one coat of release but seems it was not enough and it ended up real stuck to the mold. Is there any method or procedure that could help me remove the part from the mold? hot water? apply more release between part and tool ? if able to open a small gap in between? any other advice that you could provide and help me out if possible, based on your experience.

I real appreciate your support on this one its work-related issue.

SWComposites (Aerospace) · Answer 1 · 2023-05-20 15:19:42

What is the shape of the art and tool?
What are the part and tool materials?
Try using thermal expansion difference between part and tool; either put into a freezer or an oven, or apply local heating, then try to pop the part off. Depends a lot on the shapes. Try inserting wedges or pry bars (carefully) between the part and tool.

Cisnerjo (Aerospace) · Answer 2 · 2023-05-20 15:56:19

Hello SWComposites thanks a lot for your reply Its a radome and its made with Epoxy prepreg and foam core. the edge band is a solid laminate area but the rest of the part is foam core covered by 4 plies of prepreg on each side (tool and bag side)

SWComposites (Aerospace) · Answer 3 · 2023-05-20 16:02:11

Ok, so presumably an exterior mold surface. A metal tool?? If so, then heating it up might help, though the part is presumably fiberglass or quartz fiber, and I don’t recall the CTE of those of top of my head.

Cisnerjo (Aerospace) · Answer 4 · 2023-05-20 16:03:47

I already inserted some wedges and poured an small amount of release agent Frekote, will leave it on it for 15 more minutes in order to attempt to get as much release as needed all the way to the bottom, then will follow your recommendations by removing the wedges and will put it on the oven at 150°F for at least 20 minutes. Hoping this helps so how since it can be heard popping when putting the wedges but usually take two wedges and air to pop-up but this time it's not happening. I already placed 12 wedges all around the periphery but not popping at all.

Thank you so much for your advice SWComposites and if possible for you to provide any other idea will be greatly appreciated.

Cisnerjo (Aerospace) · Answer 5 · 2023-05-20 16:04:54

RE: Composite Part Stuck to a Mold

Cisnerjo (Aerospace)

(OP)

20 May 23 16:04

Thanks, Its a fiber glass tool.

Cisnerjo (Aerospace) · Answer 6 · 2023-05-20 16:07:50

SWComposites, the part it gets Autoclave cured with 20psi of pressure and cure at 260°F, do you think if we apply the same amount of heat could help some how or 150°F should fine?

Cisnerjo (Aerospace) · Answer 7 · 2023-05-20 18:28:33

Finally was able to removed it from the layup tool. Hope this helps to someone else in the future, placed several shims around the radome periphery placed a generous amount of release agent let it set for 20 minutes then removed all shims and placed the tool on the oven at 170°F for 30 minutes. After that start it to locate the shims back and it popup right away,

Thanks SWComposites for your valuable support!! much appreciated !

Compositepro (Chemical) · Answer 8 · 2023-05-20 21:15:18

The lesson is that whenever you are preparing a mold surface that is new or reconditioned (cleaned or sanded) multiple coats of release are required. The number I have generally heard is five coats. Most stories of release problems are similar to this one. The time required to do five coats properly is very painful when production is behind schedule. Until you experience the greater pain of a problem with releasing the part.

SWComposites (Aerospace) · Answer 9 · 2023-05-20 22:43:36

Good you solved the issue.
But in the future apply more layers of release agent, and be sure all resin is removed.
I doubt the release agent helped, as I don’t think its intended as a solvent to separate cured surfaces. Probably was the use of shims and application of heat.

SWComposites (Aerospace) · Answer 10 · 2023-05-20 22:50:28

Also, you now have uncured release agent on the part. Which might cause problems with painting unless somehow thoroughly removed.

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Composite Part Stuck to a Mold
2