vacuum infusion laminating

[HWL]

I saw a boat manufacturer using this term describing their manufacturing process. Is this the same thing as vacuum bagging? better,worse,as good as?they were really throwing this term around alot in their advertising as the best thing going. any insight from the unbiased professionals on this site. thanks

[ErikG]

Infusion is not entirely the same as vacuumbagging, but using a vacuumbag is a part of the process.

With Infusion you tape the bags down over the dry laminate and then feed the resin though the laminate stack under pressure. This "should" make the laminate free of air entrapped voids and improve on the resin/enforcment ratio.

Infusion seems to me (as I do not yet use it) like a great way to increase the quality of the workplace tremendously, less fumes, less resin splashing on your clothes and unprotected skin areas etc. Higher quality laminates, less envioromentally hazardous spills (hopefully) and stronger or lighter laminates.

Drawback is increased costs with disposables like bags, bleeders etc, but if you already vacuum it shouldn't be a big deal.

[nassaw]

Eric is exactly right and if you want to learn more about RI. Henny has a nice page on the process and even has a video clip of infusing a part.
http://www.fram.nl/workshop/controll...fusion/cvi.htm
Good Luck

[Ron Cook]

Infusioning large parts can be complicated. I have infused some small part, thats pretty easy.

What seems a better way to go is a laminate product like "sprint" from SP.
It differs from prepreg in that the resin is not part of the structural part of the laminate but a seperate sheet sandwiched between the structural parts. And it does not need to be de-bulked the way true prepregs do. Also so it drapes much better.

It does use vaccum bagging and heat. plus the product must be stored cold. It is also reasonably priced.
Happy laminating,

Ron

For a small shop and or one-offs I beleave it is less complicated with less what ifs.

[Dutch Peter]

Originally Posted by Ron Cook

Infusioning large parts can be complicated. I have infused some small part, thats pretty easy.

Ron,

What do you mean?? Is a 60 ft boat a small part? Check out the attached picture (that's a 40 ft-er). The decks are done the same way.

[Ron Cook]

Dutch Peter,

My idea of a small part is one that won,t break the shop if you lose it. depending on the shop it could be a 40'er or a couple of hatches.

Infusion is a big subject I looked into it in depth. After alot of investagtion desided it did not suit my needs.

It obviously works very well for many shops.

It is my humble opinion that that procducts like SP's Sprint is a better way to go.

Happy Laminating,

Ron

[SamSam]

Originally Posted by ErikG

With Infusion you tape the bags down over the dry laminate and then feed the resin though the laminate stack under pressure.

Eric, I agree with everything but this. I think the resin gets sucked through the laminate by vacuum.

[ErikG]

I also agree with everything including the part where you quoted me, but of course it could have been written as clear as your reply was.

It really shoud have said under vacuum instead of under pressure, but it is under preassure because of the vacuum ...

[Herman]

Resin infusion has it's advantages, but also it's drawbacks.

The explanation Eric gave is correct, one could discuss about the vacuum or pressure part. To be completely correct, a pressure difference, created by pulling a vacuum onder the bag, will drive the resin into the laminate.

Advantages of resin infusion:

-high glass content of laminate
-better working conditions for the crew
-less styrene emission (if polyester is used)
-thick laminates in one go
-thicker fabrics can be used, they are cheaper
-more fabrication details can ben included in one operation
-less skilled workforce could be used: untill the resin port is open, mistakes can be corrected

Disadvantages:

-higher cost of inventory (vacuum pumps, generator)
-cost of disposables
-more engineering needed to get a good flow pattern

About size and infusion:

Size is not really the issue. What makes infusion a difficult job is the complexity of the part. Sharp corners, large holes (windows), stairs, etc make infusion more complicated than a relatively flat sheet (boat hull).

I try and attach 2 photo's of projects we have been involved with:

One is a 23 meter powerboat, infused in epoxy resin, in one shot. (jpg file)
Second is a flow prediction of a complex boat deck, with window holes cut out already, stairs included, part of the steering console on top of the roof added, etc. It is a zipped AVI file.

Some recommended websites:

www.fram.nl
www.polyworx.com
www.brandscomposiet.nl

[ErikG]

Regarding consumables...

Has anyone tried the reusable silicone bags? I read about them somewhere... Unfortunately I can't remember where...

They used two bags (IIRC) per part the inner would be a flow-assisting bag that would be inflated (I guess) to help the resin flow all over the part. Then the inner bag would deflate and then the final level of vacuum/suction/pressure (whatever) would be applied on the outer bag.

Sounds clever to me, probably pretty expensive, but might be worth it as they are reusable. Don't know about longevity or anything hense my question.

Anyone seen them in use or even used them?

If usable wouldn't they make a great pairing with UV curing resins?
Think about it, any overflow goes back into use as it wont kick until exposed.
And the UV system gives you as much time as you want or need until you swith on the lights and start the curing process.

My bad luck is probably that silicone wont like the UV and degrade quickly, but if not...

Shazam!

What yall think?

[Herman]

Indeed this sound great. In theory, it should all work, but I have not seen too much users who really have succeeded in getting the thing working properly. Some of the pitfalls to come over with:

-Silicone does not like styrene
-Silicone does not like UV (I will see if I have a piece of silicone to put in our UV tester)
-UV curing resins can't be used if any bulker material is used, like core-mat, or foams
-Silicone is highly expensive, and it is hard to justify the cost against the number of mouldings.
-Styrene residue on the mould is a pig to get off.
-UV light is a pig to work with. You really have to take good care of yourself, or burn marks or damage to the eyes can occur. I have no figures about cancer, but better safe than sorry.

One of my first attempts was a small (1 meter) mold of a boat. It could be seen at the METS 2004. It took me a fair amount of time to construct that mould. (approx 10 hours or so).
To cut labour, we have been looking into sprayable silicone, but the above mentioned problems stay a problem.

I presume you have been reading the "Composite Fabrication" magazine or something similar. Had a 3 page article about silicone top moulds.

However, we are looking at some alternatives, which seem to look more promising.

[ErikG]

What alternatives Herman, you have to give me more...

If I remember correctly the UV should ba able to cure a relatively thick stack (dunno if its true though) and "some" core, the meaning of which eludes me...

[Herman]

About alternatives, I can probably say more in a couple of weeks / some months. I have people working on it.

Did not find any silicone yet, to put in the UV tester. I am affraid I threw away the whole lot when cleaning up.

[Danielsan]

Maybe not the right place?

Somebody knows about Vacuum generators? could they be used?
I see they go -27Hg and about 400l/min.

any hints about this?

greetz,

[Herman]

Vacuum generators? What are they? Basicly there are 2 types of vacuumpumps (used in this industry).

Either a rotary pump. (rotary vane is most used).
Second option is a venturi pump, but these are very limited on capacity.