Phenolic tube ducts

[Jim85]

Hi guys,

I'm currently manufacturing some tube ducts out of glass phenolic. The lay up is fine as the mould is split in half. Once the duct is joined we then have to pull through a rubber intensifier. We are have some trouble getting this through efficiently and removing it effectively after curing. Sometimes the intensifier is damaged pulling it against the cured glass. Any tips that could help me?

Cheers

 

[MikeHalloran]

Collapse it by evacuating the lumen?



Mike Halloran
Pembroke Pines, FL, USA

 

[Jim85]

Thanks mike,

I can't say that I've ever heard that saying before. Can you elaborate?

 

[MikeHalloran]

"Lumen" means "the hole in the center of a tube".

From your context, I took 'intensifier' to mean a tube of some sort that you pressurize in order to compress the wet laminate.

If you're just using a solid rubber slug, consider making it hollow and pressurizing it during cure.

Then after cure, you can deflate it, and pull a vacuum if you need to shrink it further.




Mike Halloran
Pembroke Pines, FL, USA

 

[Jim85]

Ok thanks,

I am using a hollow rubber tube intensifier that gets pulled through, I then apply an outer bag with a bag down the centre of the rubber intensifier.

 

[Compositepro]

How is the rubber tube an "intensifier" if the tube is bagged inside and the part is bagged outside? It is simply a rubber mold. Why are you having trouble getting it out?

 

[Jim85]

I have a hollow glass mould that I lay up on to which gives me the A surface then the rubber tube is pulled through the centre which then gives me a smooth B surface. The rubber tube is not layed up on. As for a bag down the centre, this pushed out on to the glass fabric which then pushes on to the glass mould. This is why I called it an intensifier. Because the shape of the duct involves like a swan neck shape the rubber sticks to the cured glass, the only method we have is to pull it out but this has stated to damage the tube as the cured glass becomes quite shape.

 

[MikeHalloran]

>>>the cured glass becomes quite shape. <<<

Assuming you meant 'sharp', yes, phenolic/glass leaves super-nasty sharp edges and spikes where it doesn't get fully compacted.
... which might be resolved if you pressurized the rubber tube a little during cure.

Or maybe I am misunderstanding the problem.

Mike Halloran
Pembroke Pines, FL, USA

 

[Jim85]

Sorry I did mean sharp. Once the whole component is bagged ( outer bag and internal tube bag) it is pressurised at 60 p.s.I and held there for dwell. The problem I have is getting the rubber tube down the middle as it is pulling on wet glass prepreg and removing the rubber tube after cure as its pulling on cured glass. Is there any sort of lubricant that will help input and removal that won't affect or mark the prepreg during curing?

 

[Compositepro]

You could try pulling vacuum inside the rubber tube to collapse it.If the rubber mandrel is so difficult to get in and out I would question whether it is properly located relative to the fiberglass mold. What kind of rubber are you using and what kind of release coating? Just about any rubber will quickly degrade in direct contact with resins during cure. FEP films are usually used to protect the rubber and to improve release. These can be surface treated so they permanently bond to the rubber.

 

[Jim85]

Thanks composite pro. That's very interesting. I will look in to the FEP films. As for the material of the rubber I can't be 100% sure as it was supplied with the mould tool from the customer. The release agent that we use is call marbocote.