Talk Composites - The Forum for Advanced Composites

problems with infusing

http://www.talkcomposites.com/Topic23423.aspx

By Thomb - 5/30/2017 6:18:02 PM

Hi all, im trying to make some exhaust protectors from carbon. i now made 20 of each and only 5 of them are good enough to use. The problem i run into is that all the flat area's are fine but 2 spots where 2 bumps are, always fail.

Here is the mold, polished and working like a charm. 

https://static.afbeeldinguploaden.nl/1705/268356/ArZhK5su.jpeg

This is how every part comes out shiney but always bad on the bumps.

https://static.afbeeldinguploaden.nl/1705/268357/tloSmFap.jpeg


So this is what it looks like every time around the bumps/holes:
https://static.afbeeldinguploaden.nl/1705/268358/vp5v7LX1.jpeg
https://static.afbeeldinguploaden.nl/1705/268359/ddutrUTZ.jpeg


https://static.afbeeldinguploaden.nl/1705/268360/sEANTO5h.jpeg




After this i tried it with some rubber gromets around the holes to maybe push the fabric down more but still there. I also tried a fast infusion and a slow infusion but same result.

https://static.afbeeldinguploaden.nl/1705/268361/QfsQMW0M.jpeg


But still this as result:
https://static.afbeeldinguploaden.nl/1705/268362/kQJEycaE.jpeg
https://static.afbeeldinguploaden.nl/1705/268363/kVWbWuoF.jpeg


Does anyone have an idea what i do wrong or can do diffrent? its costing me too much now. I always let the resin sit for 10 mins after mixing. full vac no leaks.

these did work:
https://static.afbeeldinguploaden.nl/1705/268364/CwZGmtCP.jpeg
By Thomb - 6/3/2017 9:44:08 PM

Warren (Staff) (31/05/2017)
Both the suggestions are good and may work.  However you choose to try, the key thing is ensuring the material and bagging stack do not lift from the mould surface.   I would favour a cut disc out of the cloth for this one, then overlap a second piece of cloth for the recess.  There is less surface distortion of the main piece of cloth that way as you are not trying to force the cloth into a raised feature.The inside of the raised feature when demoulded is unlikely to be so visible that it matters if the weave on that piece has slight distortion.


how big would you advice to make the cut? the complete hole or partial?