Talk Composites - The Forum for Advanced Composites

resin infusion problem

http://www.talkcomposites.com/Topic7372.aspx

By santana-dk - 8/7/2013 4:10:11 PM

Hello 

 As the title says I have had some problems infusing flat carbon/aramid sheets.  I am using glass as a mould so i can get as smooth sheet as possible.
 I use EC mould clean > followed by Easy Lease x4 times. the sheet is 32cm X 26 cm and 160ml of resin was used.
 After 1 hour or so i Lay:
- 1 Layer of 300gr Plain weave Carbon 
- 3 Layers Of Kevlar 280 gr 
- 1 Layer of the same Carbon. 
 -Peel Ply
-P3 Release film Perforated
-  Infusion Mesh
- Resin infusion spiral
- Bagging film

http://www.talkcomposites.com/Uploads/Images/7650b625-982e-4a80-bbc5-e412.jpg



 Since i didn't have more resin infusion resin I used EL2 Epoxy Laminating Resin that i let it be heated by the sun for 1 hour. I could clearly see the the viscosity of the resin had changed. i  For the Mix Ration I then used with 2/3 of  AT30 Epoxy Hardener FAST in conjunction of the Slow hardener since i didn't know hoe fast the infusion process would take ( The  infusion process took under 25 secs BTW).
 The bag didn't had any leaks since i let it be for 1 hour.

Room temperature was close to 30 degrees and it never dropped to under 25 during Gelation time.
i demolded the sheet after 17 hours.
http://www.talkcomposites.com/Uploads/Images/d57b5132-f1d4-45ab-9547-7c04.jpg http://www.talkcomposites.com/Uploads/Images/00567227-5b94-4408-9467-b53f.jpg

 So where in the process  did I go wrong ? 
did I pull a too hard vacuum;  should have used a Lossless vacuum regulator ?
or should i just leave it a full day or more before demoulding ?`
Any tip will be appreciated.

Santana
By DD-Compound - 8/8/2013 2:53:00 PM

Hello,

this is my first post here, so my name is Dominik and I just read this problem.

I think this is one of your first infusions.
There are some things that went wrong
First, you can never have a too strong vacuum for infusion. Than higher the vacuum than better. For a good infusion you should always have a vacumm with absolute pressure below 20mbar, better below 10 or 5 mbar.
The high vacumm makes sure that you have as less air as possible in your compacted dry fabrics. That also means that you have as less air as possible in your part.
I a classic infusion without any special avacuation hoses you need a brake zone to slow down the resin flow. You placed your vacuum ports direct at the flow media. So the resin flows fast over the part through the flow media, but depending on your vac level you overran dry fabrics and the vacuum could not saturate them completely.
Let the flow media end about 2 cm before your fabrics end and build a brake zone from peel ply wich will slow down the resin flow. Place your evacuation port (1 is enough at this part) at the end of the brake zone.
Than make sure you have a infusion resin (one that works), because other resins may have some additives that start degassig in infusion or closed curing process.
Degass the resin so that any entrapped air can be elimated before infusing.
It is also very important to have a 100% airtight setup.

If you have all these parameters you will get a much better result.

Dominik