Flow media poking holes in stretchlon

General Composites Discussions Composites Talk
#1

Okay so we have been trying to get our infusion process down and keep running to this issue where it seems to be very small pin holes are being put into the stretchlon by the edges of the flow media. If the flow media ever bunches up and makes a little crease it also tends to poke holes in the vacuum bag really easily.

This is the flow media:
http://www.fibreglast.com/product/4925/Vacuum_Bagging_Vacuum_Infusion
It is strechlon 200:
http://www.fibreglast.com/product/stretchlon-200-bagging-film-1678/Vacuum_Bagging_Films_Peel_Ply_Tapes

does any one else run into this and if so what do you guys do to fix the issue?

Here is a picture of the setup:

you can see we have resorted to putting bagging tape on the edges of the flow media to stop it from poking said holes but i’m still concerned because it seems to be impossible to get these molds to seal perfectly.

Other possible issue is the mold material itself. It is a composite material called Renshape we machine into our molds. It has proven to be very porous in the past and may be a source of the inability to hold vacuum. Though we do wax the molds very well it’s possible the air is coming from the areas outside of the part? Does anyone else have experience with Renshape?

#2

Easy solution, change your flow media…I had the same problem, get the one that is green flexible soft mesh like. You could use also some tape on the edges of the flow media but still I wouldn’t trust it.

#3

Stretchlon isn’t an ideal bagging film for infusion. I’ve always had issues with it. If you have to use it, you can use peel ply between the bag and flow media especially along the edges of the media (which tend to be the pokiest). This should help, but I feel you will always see issues when trying to infuse with Stretchlon.

#4

Indeed. Ditch the Stretchlon. The SL700 is sturdier, and 800 is as well, but these are also more expensive.

Use WL5400, WL7400 or Big Blue 100.

As for the Renshape: We had issues as well, and changed partially to another manufacturer. Also check to see if there are other styles of Renshape available.

Do a vacuum test on the bare mould, with reliable vacuum film, to see if the renshape is causing trouble. If so, you can paint the complete backside with epoxy.

#5

Thanks for all the responses. We actually tried the high temp stretchlon, as it is much stiffer and far less stretchy at room temp, before this post even went up and that seemed to do the trick. BUT could someone recommend a very stretchy bag material that would work with infusion, we have some very complicated parts with deep drafts that could prove problematic with stiffer bag materials. Though i do love the peel ply idea and that could work baring a better bag material.

Are WL5400, WL7400 or Big Blue 100 particularly compliant bag materials?

Good idea with painting the back of the mold though, might try that as we are still getting pin holes on the part.

Also on a semi related note, i have been poking around and see people getting mirror finishes straight to the carbon with infusion. As already talked about the renshape could be allowing small amount of air into the bag, so that is a possible issue.
Are those kinds of mirror finishes possible with renshape+wax-gelcoat?

#6

WL5400 and friends are not stretchable. Which means the pressure on the laminate will be all the same throughout the part (no force from the bag trying to get back to shape).

Huntsman has a couple of fillers to get better surface quality. Request some documentation from your vendor.