Hi, I'm new and I apologise if this is a dumb question. I'm making things out of carbon fibre with compression moulds and they will easily fit into a kitchen oven. I googled it and nobody seems to be using their kitchen oven. Is there a hidden problem that I'm missing? Will the epoxy fumes kill me or something like that?

The reason I want to make the switch from room temp epoxy to pre preg is that I can't seem to get a neat weave. Will using pre preg help me keep the weave straight?

My oven goes as low as 60 celcius and my moulding material can withstand 300ish. So getting the right temperature shouldn't be an issue.

Any help would be greatly appreciated.

Thanks to both Paul and Adam!

I´m probably going to (at first) just try to cut my fabric, the preg it and let it get tacky, then mould it.

To me at least, the most intising enticing prospect is to get as close to the fabric in the video as possible in the form of ease of use, to get it to almost directly stick into any corner and thus easily securing complex shapes.

Q: Is high quality professional prepreg with bagging and autoclave stronger than infusion in oven?

PS: I could just see in front of me how Paul and Matt turned on the computer in the morning and with increasing amounts of dread went through last nights posts. "Come oooon guys, why can´t you just infuse like everybody else?"

Hi Adam.

Haha I no only too well about the impatient de-mould! those results don't look bad to me at all, however your life will be much easier with the vari-preg for that part if you get your processing sorted, somthing that I only recently heard about but seems perfect for a prepreg iphone case is capitalising on the thermal expansion of the silicone.

To do this you must first make a rigid tool for your female mould, the prepreg should then be laid into this, you will layup the prepreg with snips in the corner so the weave does not have to distort. You then need to insert your silicone male tool into this and press it into the tool by clamping a flat rigid plate to the back of the silicone. When you place this into the oven the silicone will expand more than the tool, thus pressing the prepreg onto the surface with great force, the theory is that this can, if done correctly, exert autoclave pressure without the complexity cost and risk associated with compressed air. 

If you wanted to give this I go I would be very interested in seeing how you get on, we have in the past made runs of ipad cases using prepreg with a press moulding method, it would be great to see how utilising the differential in the CTE (Coefficient of Thermal Expansion) of the materials works!

Infusion is by no means the only processing method we recomend, however if done correctly the performance is rivalling that of prepreg, and cost can be much lower, but prepreg processing and matched tooled methods will always have their place, In our production we are about 50/50 prepreg/infusion, although going back 3 years and we were more like 90% prepreg, so infusion is working it's way in! Prepreg is really tough to beat for small intricate parts.

Paul Statham
Easy Composites / Carbon Mods - Technical

Hi Paul

I had considered the thermal expansion of the silicone but I was under the impression it was negligible. I was banking on it being negligible actually. I've made my moulds in such a way that if there was any expansion it wouldn't fit the phone. I'll have a look and the specs of my silicone again to be sure. If it does expand then I might have to give this up for financial reasons. Fingers crossed.

Ok I looked it up and I got "20 x 10 to the negative 5 cm/cm degrees celcius". So basically I put it in the oven and measure it myself.

Hi Paul

I gave the oven method a go and it worked out surprisingly well for my first attempt. I put the silicone male and female in the oven together instead of tooling a new rigid female. To counteract the female expanding I boxed it in and so it could only expand inwards and help stop the male expanding. I did still get a few minor voids but it's progress. I'm going to tweak it and try again tomorrow.

Also, I took your advise and put big cuts in the weave near the corners and I think you have fixed my wondering weave problem too, thank you so much for that.

Fingers crossed it will fit the phone as well as the room temp covers do.

Now they gotta learn what starting a forum is all about muhahahha

Thx Adam for running a test about it. And thx Paul for the details he gave us.

I have a question tho:

Paul said: Sealing the material; actually getting a non-stick material to apply it to, so it can be sealed and frozen is trickier than you would think.

I remember from a previous post i cant find back that Paul or Matt said Elastifilm would stick to direct contact with epoxy, while the "usual" non elastic would not. So if I'm right, thats the answer to that question?


 

 



 


    A $1000 electronic device will always protect a 10 cents fuse