Talk Composites - The Forum for Advanced Composites

carbon wet-out consistancy issues.

http://www.talkcomposites.com/Topic15349.aspx

By jono - 3/4/2015 10:32:20 AM

hi all, i'm having issues with the final part not wetting out enough consistently. I am using the same mould, same layers, same resin and temperature conditions. absolutely no leaks in the bag and obviously the same vac pump. it visually appears to infuse at the same rate every time but only 1/3rd of the time it's actually fully wetting out the weave. it seems to be luck of the draw for me? i'm using a low viscosity resin, pulling a vacuum for at least 40 mins before infusing. i've tried clamping off the vac line and resin line like the easy composites tutorial, i've also tried allowing the resin to almost empty the pottle and only clamping the resin line and allowing excess to reach the catchpot and letting it cure wit vaccuum pump going. also moving around the resin feed/vac lines. i honestly have no idea what the cause is. would appreciate any help here.

this is what my parts come out like 2/3 of the time.




yet sometimes my parts come out perfect like this (same exact mould)-ignore the traces of clay on it-




any idea what could be doing this? i'm doing a fully dry layup, no glue or gel coat (its a brake duct) should i perhaps consider brushing/spraying a fine layer of resin down and allowing it to almost fully cure to a late stage of tack and then layup/infuse? 
By VVS - 4/14/2015 9:28:48 PM

Ive had very mixed results wet lay and bagged using full vac, the best parts ive made have been using a vacuum gauge and pulling around 0.3 bar.

This has given very consistent parts and gives around 0.9 mm thickness with three layers of 200grm cloth.