New twill fabric full of air bubbles and pinholes


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Legoman
Legoman
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Hello guys!

My new fabric just arrived and I made for my gsx-r the frame protectors. But! It is full of air. The method is the same and the materials as well what I used before. Except the first layer which is the 200g/m2 twill fabric. 
First layer-200g/m2 twill carbon
Second, third-400g/m2 biaxial +-45° carbon
Release agent-Chemical from EasyComp.

When I started the lay up, I noticed that the fabric reactives not so good with the tacky spray (fusion fix from EasyComp. as well) than the other fabric which I used before--->It is 200g/m2 too but it was a bit more expensive and softer and reactived with the tacky spray very well. 
It is nonsense, but it is possible if the twill carbon fabric quality is lower than can be formed air traps in it? 
I degassed the resin, made the drop test!

Here is the result with the "old" twill fabric.- Perfect.


And here is with the "new one"- And you can notice at the edges the part is resin rich too.





Lester Populaire
L
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Legoman - 5/5/2019 8:02:24 AM
Hello guys!

My new fabric just arrived and I made for my gsx-r the frame protectors. But! It is full of air. The method is the same and the materials as well what I used before. Except the first layer which is the 200g/m2 twill fabric. 
First layer-200g/m2 twill carbon
Second, third-400g/m2 biaxial +-45° carbon
Release agent-Chemical from EasyComp.

When I started the lay up, I noticed that the fabric reactives not so good with the tacky spray (fusion fix from EasyComp. as well) than the other fabric which I used before--->It is 200g/m2 too but it was a bit more expensive and softer and reactived with the tacky spray very well. 
It is nonsense, but it is possible if the twill carbon fabric quality is lower than can be formed air traps in it? 
I degassed the resin, made the drop test!

Here is the result with the "old" twill fabric.- Perfect.


And here is with the "new one"- And you can notice at the edges the part is resin rich too.





To me this looks like a processing issue. The fabric is not in contact with the mold in the radii. You need to be more careful placing the fabric in the mould. Start in the center and work your way outwards and push the fabric neatly into all corners. A dabber might help. It's not a very complex part so shouldn't be too hard to get perfect.

Hanaldo
Hanaldo
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Spot on ^ 

This is a bridging issue. These are very simple shapes, there's no need for spray adhesive - it may be making the issue worse by locking the fabric in a bridged position and not allowing it to slide under vacuum. Ditch the spray adhesive and position the fabric when you pull a vacuum.
Warren (Staff)
Warren (Staff)
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Depending on the quality of the fibre, type of tow etc sometimes some fabrics, despite being similar spec, can feel stiffer and less able to be draped than others. This could mean you are getting bridging as suggested above where your technique, although fine with the other cloth, needs slight revision to get it perfect with this one. 

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant
GO

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