Press Pad for Phenolic Sandwich Panel 2

[Cisnerjo1973]

Hello,

I would like to ask for suggestions on how to make a press pad or something similar that help me on the radius area of a part, this area is critical for next assebly of the part, this is located on the bag side of the part on the top edge of it, I made a fiber glass press pad using a good part to obtained the needed radius but everytime we make it obtained the marks of the press pad on the part as well some wrinkles, I change the way I bag the part by placing the release cloth then the air breather N10 then the press pad on top to avoid the marks and it work but still seeing the wrinkles along the part, I dont know what else to do or If Im doing something wrong, when laying up the part the prepreg gets as much as we can thight no loose indication that would let us have the wrinkle when curing, so seems like a composite press pad is very hard to achive the desire shape with no wrinkles, is there any other materials that I could used for a proper press pad that wont cause wrinkles or marks on my parts?, please need some input from the experts since I already tried everything to make it looks constant and perfect everytime we build the part, as a reference the wrinkles are on different areas all the time as well different severity from part to part its not constant on same spot.

Best Regards!!

 

[berkshire]

Have you tried using heavy mechanical felt i.e. perimeter felt between the perf pad and the vacuum bag in that area to increase the local pressure?
B.E.

You are judged not by what you know, but by what you can do.

 

[Compositepro]

Preformed caul plates are used to do what you want. Airtech has a product called Airpad, which is a sheet of uncured rubber. You create a tool representing your final part shape, lay-down FEP release film over this part and then strips of rubber sheet to fill the areas where you want to control part shape accurately. Go through a cure cycle and you will have a flexible but firm caul that can be reused a number of times to cure production parts with accurate bag-side surfaces. Strips of epoxy prepreg can be placed with the rubber to maintain shape even more accurately.

You can also use vacuum-bag sealant tape in place of Airpad or felt breather material. It will conform to contours better than felt and will hold shape during cure of the part.

 

[Cisnerjo1973]

Hello Berkshire, thanks for your reply, No I have not tried any felt, we have a felt called Pyropel is that the one you mean? so this felt can be used instead of the press pad? or can be placed under the composite press pad I made? I was also thinking to bond N10 to the press pad made so I can achieved a not so rigid area that could create more problems than help.

I also noticed on the web theres a material called pressure strip from Airtech I dont know how good this material could be and if would apply to be used for the issue I have,

Thanks for your support on this matter,

 

[Cisnerjo1973]

Compositepro Thanks a lot for your reply. I dont have Aipad material but do have a material from airtech called Pressure Strip, do you think this might work similar to the Airpad? pressure strip comes similar to vaccum bag sealant presentation of 1" strip rolls.

Thanks a lot for your great support as always

 

[Compositepro]

https://www.airtechonline.com/Pressure-Strip

It is the same material just a different format. If you lay-in some strips of dry or prepregged fiberglass fabric the pressure pad can be reused a number of times.

 

[berkshire]

Cisnerjo1973 ,
The Airpad/ pressure strip will do a better job than the felt, because it will give a smoother less lumpy finish, it will also transition out with less chance of leaving a wrinkle in the finished part.
B.E.

You are judged not by what you know, but by what you can do.

 

[Cisnerjo1973]

Thanks a Lot for your helpful support! It's really apreciatted!!

Thank you gentleman!!