What benefit does the embossing give? Do you have a peice of the film that you could send me?
the embossing keeps the sheets from sticking to the resin.i use 1mil painters plastic.if the resin starts to firm up.it is a hassle to remove.its been awhile since i worked with pre preg.so i dont have any of the sheet.some folks here that do work with it regularly would have some.it gets chucked out when you do a layup.
reckon that there is a lesser amount of surface area that is in contact with the resin in the prepreg, so it’s easier to come off, but still protects the entire surface. besides that, NO idea why prepreggers use embossed film.
Also, maybe when you are debulking, and you leave the top layer on, it provides an airflow through the stack…just a guess on that one too.
the surface provides better air flow than a nontexture backing
Solution based prepreg is made by running the fabric through a bath of resin diluted with solvent. Most of the solvent is removed as the prepreg is B-staged in ovens. Residual solvent can change the flow properties of the matrix (viscosity vs temp) and can also increase void content. I’d imagine the embossed film helps with the removal of that solvent. The channels are not filled with resin, so vapors can flow out.
There seems to be some confusion/misunderstanding from watching only the video, so I’m quoting the article by David Algie that can be found on Woodward Aerospace’s website:
"All you really need to make your own carbon fiber prepreg is the right prepreg plastic embossed sheet. You can use just flat plastic but it gets an airlock of sorts and is almost impossible to pull off the carbon fiber.
I make an 8’ by 4’ table at a time by just spreading the correct amount out on the fiber and then putting the top sheet of plastic on it, and then cut the parts right there and then and put the lot in the freezer.
Over time and experience I have formulated the right amount of epoxy to use for first layers and then less for the next layers, you always want a richer layer on the tool surface. I tried blending different hardeners to get the cure temp and time I needed but have had the best results with the high temp hardeners, this gives you a wider B stage time so with the low pressures that a vacuum gives (as opposed to an autoclave cure) you need enough time to bleed out gasses and general resin flow. The hardener I use needs about 7 hours at 180F, or about 2 hours at 250F. I tried using B staged prepreg with vacuum like you have to with autoclaved parts but the low pressure doesen’t work well with that, so all my vacuum prepreg is A stage stuff. Finished parts I generally get a 40% resin content, and autoclave parts under 20%. With a vacuum I can get very close to a pinhole free surface, and with B staged fiber in an autoclave the parts are pinhole free. You generally need to look at the back side of any layup to check it’s quality, this is where you see the usual overuse of resin, giving a typical fluid lock as too much resin is impossible to bleed out, with a fluid lock like that the fiber isn’t really interlocking over each other and you give up a lot of part stiffness, and add a lot more weight that the vehicle has to carry around for life.
Prepreg always has either plastic on both sides, or plastic and waxed paper, leave off one of those and your cutting table or patterns are somewhat gooey…
I don’t know what the viscosity of this resin is, but I heat it slightly to get it thin enough, bit thick as it is cold.
I just use a spreader to spread the resin out, a Bondo spreader to be exact. I do it in quarters of the table and measure the poured amount to get it even.
Believe me, don’t use flat plastic to make your own carbon fiber prepreg, especially if you make a very rich batch. All types of fiber, be it 3K 2x2 carbon, 7544 fiberglass (my favourite for moulds) or 6K uni carbon needs a different amount of resin. Carbon first layers I use 600 grams of base resin, before adding hardener, 450 for layers after that. This is lean enough that the plastic will almost fall off itself, and for the autoclave stuff it does fall off, and you would swear that there is NO resin in that carbon."
interesting… most of my experience with carbon fiber has been with using low temperature cure prepreg from ACG and they don’t use embossed plastic film. One side is a sort of paper with a glossy side against the prepreg and the other side is a flat plastic sheet (with no embossing). It is somewhat a pain to get the plastic sheet off sometimes, but you get pretty good at it after a while and it is no where near “impossible”.
I have only been speedreading this thread, and did not even see the video, but I can say 2 things:
-I can ask for embossed film at Airtech in smaller rolls. I will need to take a full roll, but I am prepared to do so. (same for high temp (426C, 800F vacuum film).
-For the European people here: Use Sicomin SR8500 resin and KTA21 hardener. This is specifically made for prepregs. Wide B stage, low viscosity after heating.
Wow…did not know I would create such a stir with the video…anyway, we’ve been receiving quite a few comments…mostly…where do you buy that embossed film?!! We source it locally from another company that buys it by the pallet load.
However, I just got off the phone with Anders and he wanted to know what the film was so that people could go in together to get a roll from Bloomer and share it. They have probably 100 differnt variations of this stuff so it just depends on what would suit most applications. I’d recommend 2 or 3mil small or medium diamond emboss pattern. The Bloomer Plastics DC000A 3.0 mil would probably fit most applications well. Also, yellow in color works pretty nice. Whomever decides to spear-head the sharing/dividing operation should definitely give Bloomer a call. They are all very friendly and knowledgeable. I considered setting up a middle-man operation but right now we are pretty focused on getting the LP1 aircraft flying (hopefully iin the next few months here). Also, I will refer some of the aviation guys to this thread if they would like to “put an order in”.
I have used two Airtech products for this purpose, the Dahlar125 and Airdraw2. Both work better than flat plastic (impossible), but the “cracked ice” pattern is pretty shallow and adheres too much. I believe the diamond or taffeta pattern from Bloomerplastics would be a better choice.
Also…no wax in these cups…and yes wax is a bad thing…though not the end of the world like some seem to make it out to be.
Not sure if my first reply to this thread went through…anyway I authored that video. Talked to Anders on the phone…If a group was going to order from Bloomer you will likely want DC000A 3.0mil small diamond emboss pattern (in yellow).
In the future we will probably start supplying rolls (or possibly smaller quantities) to people but right now we are focused on the LP1 aircraft flying in the next few months so we don’t really have time to be the “middle-man” right now. If someone does step-up to be “middle-man” for a group order just be aware that a pallet is pretty large…so make sure you have the space to store it.
Just wanted to add some links to more information…
Algie Composite Aircraft has a yahoo discussion group that you can do a search for information…like what resins we use, project information, etc. I believe you have to become a member to do a search but it’s free. Also, if you have questions for David Algie or anyone of us you can ask them there http://groups.yahoo.com/group/algiecompositeaircraft/
We have a facebook page if you want to follow our progress on there as well. We’d certainly appreciate the support. Click the link and then click “Like” http://www.facebook.com/WoodwardAerospace Though we have many orders from the aviation community…I’m kind of hoping the LP1 will inspire people to become pilots. To find out more about getting your pilots license check out http://eaa.org/learntofly/
I’m not trying to link traffic out of Composites Central but rather just pointing to more sources of information. I’m also not trying to sell anything…well except for airplanes…Hope everyone can see that this isn’t spam. We believe in the freedom of exchanging information and ideas. Doing so with composites can only make this a stronger and more progressive industry.
No worries Woodwardaero. Your first post got flagged automatically by the computer. This happens to new users and recently I’ve had to up the filters since this forum is getting hit really hard with spam. Feel free to post links to whatever sites you find useful. A long as it helps users here it’s fine by me.
I sent an inquiry to Bloomer about the film. I live in the same state so hopefully shipping wouldn’t be to much. I’ll let everyone know what they say.
Thanks Woodward for joining and adding your input.
thanks woodward for your replies.i had thought about asking a question on your website about this film last night.it was nice to see you post with info today when i opened the thread.you can count me in on a reasonable quantity of the film when its sourced.thanks for all the help on sourcing this film guys.this film will make this process much easier.the painters plastic isnt impossible but its not very easy.usually involves lots of cussing.
Thanks Canyon. I built a forum once for our Ravin Aircraft builders and the spam was CRAZY!! Had to take down the forum eventually. The spam just wasn’t worth it so I understand what you’re going through.
Anyway, the last time I talked with Bloomer they quoted me (and I’m going on my memory here) a price on a minimum order of 500 lbs at about $0.98 per yard (54" roll if I remember correctly) and that was with shipping. Again, I have no financial interest or stake in Bloomer Plastics but everyone I talked to there was very friendly, helpful, and knowledgeable. I’m sure they will get you a quote pretty fast.
Thanks for the welcome.
So I realize this is 4 posts in a day on the thread but I’ve been thinking about this all day…
After talking with Anders and re-counting how many people have emailed or called us about a source for the embossed plastic, I figured I could “test the waters” a bit and take on the role as “middle-man”. I’d have to hire on some part-time help but that part is easy and I have no problem doing it as I have the space…and can always use an extra hand. However, I’m not going to do this for free obviously. The only thing I would charge is a small handling fee, shipping, and shipping supplies. I am more than happy to sell the materials at cost. Like I tell people that ask me to do some composite work “If you pay for the labor I can pay for the materials”. Basically most people don’t understand the enormous amount of labor that goes into making a plug, mold, part, etc.
If someone is willing to be the middle-man for less, or free, that’s fine and I would be happy to refer people to you but chopping up, packing, and shipping a bunch of rolls takes time…and time equals money. It’s difficult at this point in time to give quotes. I don’t believe in “minimum orders” so any amount would be fine but I would encourage at least 10 yards. I can also set-up price breaks for larger volume orders, let’s say starting at 100 yards. I don’t have any idea of what I would price it but normally I would wildly-guess that 2x the cost would pay for the handling part of things (so if my cost is $1 a yard I would charge ~$2 plus shipping). The price could change and I will post that as we know more.
What I’d like to know ahead of time is what the demand might look like. If you have any interest please reply to this thread with a quantity desired, or email me at parker@woodward-aerospace.com, or give us a call at 1-888-407-7797. My intention is not to make financial gains from this deal but rather to cover some costs and provide what seems to be a much needed, albeit niche, product to a market of composite experts looking to better control the quality of their product. That is essentially why we make our own pre-preg. Thanks for the consideration and please forward this to any who may be interested in the embossed plastic. The way I see it the more people we have interested the greater discount we could all get.
Also, please realize that it will be at least a month before anything is shipped out as Bloomer Plastics quotes 2-3 weeks plus delivery time. If enough people are truly interested then I’ll take this on so please contact me with a predicted quantity you would want. If for any reason I am unable to take this on I have a network of people that would likely be able to and if for some reason they are not I would gladly send any contact information/order info to someone that wanted to take this on.
Oh and I would basically be ordering the 3.0mil small diamond in yellow…what we currently use. It’s worked pretty well, even for very large pieces. I suppose very complex curves would be a bit difficult to lay into a mold or whatever but relief cuts and various other tricks that I’m sure you all possess would solve this…and of course we can always share new secrets learned.
Also, if you have any reservations about this, please contact me. I can assure you that all monies would be safe, and I’m not even asking at this point that people pay-in-advance. To give you a greater idea of our credibility we currently escrow deposits with a third party for our LP1 aircraft. These are $5,000 deposits and the reason we escrow them is to show our clients that our company is strong and plans to be around for a long time…we would never use deposits to fund research or development and that’s an important difference between us and many aviation businesses with new products. So I just wanted to say all that in case anyone has any worries especially because I’ve just joined this forum.
So with all that said…let us know ASAP what quantity you’d be willing to buy.
Parker
http://www.woodward-aerospace.com
P.S. I’m still amazed at the power of the internet…20 years ago this would never happened, all these buyers and makers in one place. It’s just cool when you stop and reflect on it.
Parker,
I would want 20 yards initially, for testing purposes. If there was a small-ish 50-yard price break, I would probably opt for that. If I like the process subsequent purchases would be 100 yards.
Thanks Anders…why don’t we setup price breaks like this…
50 Yards- 5% off
100 Yards- 10% off
250 Yards- 20% off
500+ Yards- 30% off
1000+Yards- 50% off
Again, if we have enough people interested it’s possible I could get a price-break from Bloomers for a larger order. Just depends on what the demand is so let me know with quantities desired.
I think that should cover most peoples needs and beyond. Also the more you order the more you save on shipping if that wasn’t obvious. I will explore and post example shipping prices when I have them.