Wetlayup or Infusion IN Autoclave

[Drasko]

Has any one ever come up with this idea or ever tried to do an infusion in an autoclave or pressurize an infused part after the infusion was finished.

The reason Im asking is that Im getting an autoclave in a couple of weeks, good for me :), and is gonna be a big one.

NOW, i got a supplier of prepreg already so work with that is not a problem - which is more expensive than dry fabric and I was wondering if You could get more quality out of infusion when You pressurize the mold? I understand the fisics and certainly is worth testing, but i was wondering if someone has done this already?

[herman]

I recall having seem some tests at the Composites Lab near my place. It was a bit of a hassle, as you push out some resin which you need to contain. I have not heard about the conclusions though.

A customer of mine does infuse with resin, then autoclaves the part, but I do not know if they just use the autoclave as a large oven. I guess they are smarter than that…

How large is your autoclave going to be?

[Drasko]

Usable space is diameter 190cm a bit is cut down and up for rails an heaters so heigt is 150, lenght 350cm

[Moke]

We used post cure our parts in the autoclave without pressure, then about 2 years ago we thought why not use pressure too. This defiantly gave us a better looking and better consolidated part. We did learn that if we were using mdf plugs the pressure would make them unhappy and moulds needed to be well made without air bubbles which would collapse.

Prepreg is more expensive than dry cloth but don’t forget that dry cloth needs the cost of resin added.

I thought you said it was a big autoclave, we just fired up our new 1.5m diam by 15m autoclave.

[Drasko]

We used post cure our parts in the autoclave without pressure, then about 2 years ago we thought why not use pressure too. This defiantly gave us a better looking and better consolidated part. We did learn that if we were using mdf plugs the pressure would make them unhappy and moulds needed to be well made without air bubbles which would collapse.

Prepreg is more expensive than dry cloth but don’t forget that dry cloth needs the cost of resin added.

I thought you said it was a big autoclave, we just fired up our new 1.5m diam by 15m autoclave.

Well, for small automotive manufacture, is kinda big, but as I’m in not very technicaly sofisticated Serbia, it looks like i got some science fiction machine

[DDCompound]

Both works. Wet layup in autoclave works, but you have to find out wich pressure temperature curve will be the best. Pores are minimized and the result is if done correct just es good as a prepreg part.
An infused part in autoclave does not really make sense. If infused correct you have a void free part with a perfect vf.
But you can feed your part from outside the autoclave and squize out excess resin by the pressure in the autoclave.
I have done both, I don’t like wet layup so that I than prefer prepregs, anf infusion in autoclave only if you need the absolute maximum.

[hafizhassan]

hello.u r doing in Out-of Autoclave manufacturing process?

[Drasko]

Both works. Wet layup in autoclave works, but you have to find out wich pressure temperature curve will be the best. Pores are minimized and the result is if done correct just es good as a prepreg part.
An infused part in autoclave does not really make sense. If infused correct you have a void free part with a perfect vf.
But you can feed your part from outside the autoclave and squize out excess resin by the pressure in the autoclave.
I have done both, I don’t like wet layup so that I than prefer prepregs, anf infusion in autoclave only if you need the absolute maximum.

I just think that you can not infuse the resin from a pot which is not pressurised (which is out of autoclave) theoreticaly is possible because what metters is pressure difference between vacuum side an resin inlet but my guess is that 5bar of autoclave pressure will do so much dry laminate compaction that resin will not be able to flow? Correct me if im wrong. I agree on everything else you said.

What is a perfect resin to fiber ratio and is it purpose dependant? That’s a tricky question.

[DDCompound]

You first have to infuse til no resin is sucked by the laminate, after that you start your pressure curve to squeeze resin out. When your resin starts geling you raise the presure to compact the laminate.
The optimum vf depends on your part specification. For cosmetic parts I would choose a low vf of about 45%

[Drasko]

You first have to infuse til no resin is sucked by the laminate, after that you start your pressure curve to squeeze resin out. When your resin starts geling you raise the presure to compact the laminate.
The optimum vf depends on your part specification. For cosmetic parts I would choose a low vf of about 45%

How much pressure would you use till gel phase, and how much after? How does speed of pressure increase affect the stuff? I can pump 1bar in less than 30sec with my compressor…

[susho]

Prepreg is more expensive than dry cloth but don’t forget that dry cloth needs the cost of resin added.

Not only the cost of resin, the impregnation too. With wet lay up you spend quite some time wetting it all out. Pregpreg can be done in one cure cycle without the need for postcure too.

[findhan]

I know one local company that infuses in autoclave for aerospace parts and gets very good results shall we say. We also have some additional ports put on our autoclave that Ill be testing later in the year, but im assuming that if your clave is coming in a few weeks, it may be to late to add them already - to retrofit these would be quite expensive Im sure with all weld certification etc. Careful with patents in that regard, I understand there are a few

[Drasko]

I know one local company that infuses in autoclave for aerospace parts and gets very good results shall we say. We also have some additional ports put on our autoclave that Ill be testing later in the year, but im assuming that if your clave is coming in a few weeks, it may be to late to add them already - to retrofit these would be quite expensive Im sure with all weld certification etc. Careful with patents in that regard, I understand there are a few

What kind of ports? As for welding, I suddenly happen to have cetificates for al kinds of welding job, it just may be boring to TIG it all

[DDCompound]

There are some other possibilities than drilling and welding
I can not tell you a standard pressure temperature curve, it depends on the resin and your layup.
You can say to go up to 2 bar if the resin line is at ambient pressure and after gel go up to 5-8 bar. An infused part is not so sensible than a prepreg part in autoclave, but the result is much better.
In combination with a IMC and perfect trimming of the part you do not have to clear coat.

[Drasko]

There are some other possibilities than drilling and welding
I can not tell you a standard pressure temperature curve, it depends on the resin and your layup.
You can say to go up to 2 bar if the resin line is at ambient pressure and after gel go up to 5-8 bar. An infused part is not so sensible than a prepreg part in autoclave, but the result is much better.
In combination with a IMC and perfect trimming of the part you do not have to clear coat.

Well, I did parts with gelcoats that needed just a slight polish to perfection, but that requires perfectly perfect mold and release agent polished… From my point of view it takes less time and energy when you do a quick sanding and do a clearcoat over gelcoat or IMC or what ever the part is made of… That`s when You have a paint booth ofcourse

[DDCompound]

Yes of course, but if you want to make many pieces you should use polished aluminium or nickel moulds. With a good release agent you can get absolut perfect parts.
I know companies that have high gloss plastic mould covers that are used once and pulled off after curing. The parts are trimmed by 5 axies laser. than you don’t have to clearcoat

[Drasko]

Yes of course, but if you want to make many pieces you should use polished aluminium or nickel moulds. With a good release agent you can get absolut perfect parts.
I know companies that have high gloss plastic mould covers that are used once and pulled off after curing. The parts are trimmed by 5 axies laser. than you don’t have to clearcoat

Unfortunate is that most of my parts are one of… And the things You mentioned are a bit expensive for us that don`t make space shuttles :o

[dallasb84]

The first time I baked an infused layup… I pulled a large amount of Resin out. Resin also was pushed into the transducer port by mistake.

I locate transducer on backside of the mold for this reason using envelope bag. During infusion out of clave a vacuum gauge sits in the ports. I set ramps when the resin kicks. I also time from resin kick to gel for pressure ramp for specific resin system.

Never needed to try to infuse inside the oven. Splitting the cure and infusion makes things slightly less complicated. Vacuum quick connects are very handy.

Also plain ole air works fine.

[findhan]

[QUOTE=DDCompound;39685]There are some other possibilities than drilling and welding
QUOTE]

Im intrigued…using vac ports?

[Drasko]

I`ll stick to this method: