Need help with prepeg technology

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Need help with prepeg technology

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ZairMirza	ZairMirza posted 10 Years Ago HOT Topic Details
Group: Forum Members Posts: 3, Visits: 19	Hello. I'm Zair from Armenia , i newbie in carboan foaming and i need help pls. For first i present as i make carbon part 1) I make aluminium mold 2) I put carbon prepreg into the mould ( do not have photo) 3) I make special vacuum thermopocket 4) Make vacuum with my compressor and put it into oven. 30 minutes 100C and 2 Hours 140C 5) When it finished i have some problem with parts, check photos The edges are not glued. I think that problem is that the vacuum is not enough effort to flatten the material inside the mold. I think autoclave can resolve it problem, but it so expensive for me Pls how i can resolve it?
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scottracing	scottracing posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 460, Visits: 5.2K	I cant tell from your photos of the bag but are you using two bags? An internal bladder and an external bag? If not then thats one of the causes of the poor consolidation. are you also maintaining vacuum while curing in the oven? Can you tell us what the part is for? It looks like a catch tank of some sort? If its not for rrtaining fluods you might be better making the two halves then bonding them.afterwards. if you do neet to make a pressurised tank you will need to have a method of an intrrnal mandrel or core. This could be a vacuum bag or a pressurised bycicle inner tube or even a soluble core.
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ZairMirza	ZairMirza posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 3, Visits: 19	scottracing (11/01/2015) I cant tell from your photos of the bag but are you using two bags? An internal bladder and an external bag? If not then thats one of the causes of the poor consolidation. are you also maintaining vacuum while curing in the oven? Can you tell us what the part is for? It looks like a catch tank of some sort? If its not for rrtaining fluods you might be better making the two halves then bonding them.afterwards. if you do neet to make a pressurised tank you will need to have a method of an intrrnal mandrel or core. This could be a vacuum bag or a pressurised bycicle inner tube or even a soluble core.[/quote] Big thx for your answer. 1) Yes, we use one bag. how we can use two bags? 2) Yes, compressor is make vacuum all time in oven 3) It's test part, i try to make parts before big detail for rc helicopter 4) Two halves maybe, but it need to be strong. What bonding method i can use? Maybe links or youtube videos? 5)I have bad English, can you pls say for me about this method? links or youtube? Big thx Edited 10 Years Ago by ZairMirza
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ZairMirza	ZairMirza posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 3, Visits: 19	In future i want make this part What better and cheap - make 1 detail or two halves and bound it? how to bound it?
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Dravis	Dravis posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 592, Visits: 1.9K	Just a note on designing CF parts ... You will get much stronger parts by having a proper "radius" and avoid lots of sharp corners/edges .. That will also make it a lot easier to have the CF "conform" properly to the mould and avoid bridging and air-pockets/pinholes... For a part 1 mm thick, do not go below 2,5 - 5 mm radius, and certainly not in 3-joint corners .. You write "compressor" Are you using pressurised air or vacuum ? Yoy will need vacuum on the outside of the alu mould to make the resin in the prepreg flow out into the corners. I still feel that your mould has far too sharp corners ... "Sapere Aude"... Dare to KNOW! The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind... 103% of all people do not understand statistics... Do not adjust our mind, theres a fault in reality :-)
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scottracing	scottracing posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 460, Visits: 5.2K	Big thx for your answer. 1) Yes, we use one bag. how we can use two bags? You need to run one bag inside which is folded on itslef and left open and both ends, both ends are taped to the outer bag with bag tape. The difference in pressure allows for the bag inside to expand but I have only done this in autoclave curing and have no idea if it will work in a normal cure oven with vacuum to the outer bag. 2) Yes, compressor is make vacuum all time in oven. If you can take a photo of how you cure the part and what the bag looks like this would help 3) It's test part, i try to make parts before big detail for rc helicopter - What size rc 30 size or 60 size? I would still think you need to do this in 2 parts then bond -glue them together with a simply lap joint, you will have to put a joggle into one of the parts to extend it and create a bonding surface. 4) Two halves maybe, but it need to be strong. What bonding method i can use? Maybe links or youtube videos? The glue bond will be just as strong, probably more than the carbon material, ive only experienced one glue line failure in my career and that was due to bad prep of the surfaces. 5)I have bad English, can you pls say for me about this method? links or youtube? There are plenty of books on the subject. http://www.amazon.co.uk/Composite-Materials-Fabrication-Handbook-Garage/dp/1929133766/ref=sr_1_2?ie=UTF8&qid=1421076805&sr=8-2&keywords=composite These are pretty good and simple and show a few projects which should give you an idea, on you tube just put composite moulding into the search and it should send you on your way.
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Fasta	Fasta posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 468, Visits: 3.5K	It looks like your one bag technique should work ok as it then folds back over the whole mould same as having two bags taped together. I think maybe you should consider putting some carbon in each mould half separate and then vacuum bag this first with just 70 deg for 30 minutes. Then add more material to make the carbon join properly as you close the moulds with your bag as before. Then cook. Fastacraft Facebook page
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