Prepeeg

General Composites Discussions Composites Talk
#1

I’m doing some research and was wondering if my process is going to actually work.

My situation is this. I don’t access to an autoclave, however I do have access to a large oven. I was looking at easy composites prepreg and it lists surface quality and also filler. The surface is I think 212g and inner heavier is 430g. If I build my mold to the specs that will withstand and also use items that will withstand my curing temp of 150c for 10min can I actually vacuum seal my mold, do my normal leak down test and put it in the oven without keeping my pump running like infusion?

I look at doing this layup schedule

1x 212g layer surface quality prepreg
1x 430g layer
1x honeycomb core
1x 430g layer.

This part will have to withstand forces of downforce since it’s an aero part for a car.

#2

I’m not quite sure what your question is… Are you just asking if you can cure without active vacuum? If that’s the case, then the simple answer is yes, you can.

#3

Yes sorry, haha. That was my question. If I were to clamp my mold inlet off after checking can I transport my mold and cure without active vacuum. I wasn’t sure if the temperature increase did anything to the air inside. Sorry for my lack of scientific terms.

#4

Yeh you can do it, generally without issue. I’m certain EasyPreg won’t have an issue. Some other pre-preg systems may outgass badly and so effectively reduce your vacuum level, but EasyPreg isn’t bad enough to worry about it.

#5

Typically you should use a film adhesive to get a good bond between your laminate and honeycomb core. It could be that the laminate you will use has plenty of extra resin to get a good bond on A side, however B side is always trickier as usually too much resin gets sucked out. You may be able to use a non perforated film release to hold the resin in, but again it really depends on how much extra resin is in the laminate. You would likely find a much better bond using film adhesive than not. Would recommend to make test panels first. As for vacuum, I would recommend you leave it running until cured.

#6

Can you explain how I should do the film adhesive? I looked up things and pretty much the film adhesive I found was like a 1:1 ratio that uses a special gun to mix. Something like dp420 by 3m. Although not exactly what I need is that what you are talking about?

Should I use a non perforated release film and bag only on top or should I use a perforated release film and breather?

The issue with having my pump is that the place I’m curing it at is actually 20 min away and it’s kind of a favor of them to let me use their oven. I can see though if I can bring my pump and run a tube inside the oven.

#7

Process will depend on the prepreg system you choose, you should check the TDS for detail recommended process. But I can give you rough details; Film adhesive is basically an extremely thin scrim with resin impregnated, I would roughly recommend using 150 or 200gsm, but this is very dependent on your prepreg system, prepreg RC, product you are making, and strength requirements amongst other things. You would laminate your A side laminates debulking if necessary, then either cure, or place film adhesive, then core, then film adhesive and B side laminates followed by cure, usually using a P3 release film and breather, but again depends on the prepreg system. Its actually really simple.

#8

You will need film glue !!!
A few pre preg systems are core bondable such as mtm28,most aren’t. Thou you will get an initial bond on the part it will very soon fail.
Easy preg is a " hot roll" pre preg where the resin is placed on one side of the material to allow you to get a surface Finnish so you have less resin on your bond face than you would with an old school immersion pre preg.
“film glue” is a pre preg glue that comes on a roll like the material,depending on your core I would probably go for a 300 gram than a 150 if I was bonding onto the back of a hot roll material
Run your job with a vac pump !!! Would also have a second vac port in the job to run a vac line to a gauge outside the oven.you might of bagged lots of jobs up for infusion bot you start playing with ovens and lots of heat you may get leaks
Easy composites don’t actually make anything,the re brand an sell other peoples products,you might want to talk to SHD and see what they offer they actually make the resin systems and impregnate the materials and you can normally buy small quantities from them
Their technical knowledge is also the best in the buissness !

#9

Hojo and f1rob you both are lifesavers. Thank you!