How can I figure out how much resin is required to saturate a sq ft of fabric? In this case, 5.7 - 6oz carbon fiber.
Depends on your fiber/volume fraction.
What you need is the (estimated) fiber/volume fraction (these differ for various fabrics, and application techniques), the weight of the fabric, and the density of fabric and resin. That is how you can accurately estimate the amount of resin that will stay in your laminate.
I made an excelsheet, but cannot reach it now (server of work seems to be down)
If you could forward that to me when ever you can that would be great :).
So how can I figure that information out? Would I cut a square foot of my fabric and weigh that? Then measure the mold cavity and multiply that by the layers of fabric I’ll be using?
It all depends on 1.the percentage of the fabric to resin ration you want to achive, 2.the technique: infusion, vacuum, wet layup and even the amount of vacuum -30mhg or -5mhg and 3.the fabric itself 200gr carbon, 150gr kevlar, 450gr mat, 80gr veil etc.
I usually estimate an 1:1 percentage, which means if the fabric weights 200gr then I prepeare 200gr resin -during the procedure (infusion, vaccum etc) carbon gets saturated lets say with 150gr and the rest resin is wasted along with the one absorbed from the breather if your doing vacuum.
Here is the excelsheet.
This is the library file I use for making laminate schedules. With a lookup function in excel I just need to type the codes on the left, to create schedules quickly. (usually I need to meet a certain thickness)
I am open to all additions and corrections.
There is also foam in it, which has nothing to do with fiber-volume ratios, but I need them for my calculations anyhow.
With a bit of effort you can create a perfect excelsheet, which gives you laminate schedules for different parts of a product, the number of sq meters, a bill of materials, weight of the product, and even laminate properties.
If there are people interested to co-develop this, I am willing to share my notes and the rest of the excelsheet I am using now. It can become a powerful tool.
Thanks guys! I’ll have to do some math 
Is it possible to perfectly infuse 1:1?
You mean 50 percent fiber 50 percent matrix? Theoretically yes, samples I’ve infused were 55% to 60% Vf.
How can you control that though? I’m assuming it has to do with the thickness of the part as well as the vacuum?
I downloaded a volume fraction, weight fraction & laminate costing tool from the App store, it is made by TLC composites, it “looks” very robust and I have messed around with it a bit but have not used it to figure anything out yet.
You can build your lay-up schedule by fabric & resin type, the database is totally edit-able and it comes pre-loaded with popular fabrics (E-class, S-class etc…etc…).
You may wanna check it out, just search composites, I downloaded it for free, I think they maybe charging $.99 cents for it now.
Wow very cool! I was hoping composites would make its way to smart phones :). App wise I mean :D.
Thanks!
Much better than that, check the sheet. But keep in mind that you will have to account for resin losses in infusion mesh, foam kerfs, piping, etc. So a thin laminate will have a large loss factor, where at a certain point in laminate thickness, you will reach a negative loss factor, as in you are actually saving on resin compared to hand laminating, even when you account for losses.
And do not forget hand laminating also produces considerable resin losses.
I guess I have more math and some experimentation to go through until I can figure out the equasion necessary for the fabric and resin I’m using :/?
Typically the laminates I infuse are 65% fibre/35% resin by weight (carbon) and thats not trying to starve it.
How do you achieve that kind of infusion?
Just infuse it. Keep in mind the difference in density between the fiber and the resin.
Thanks Herman :).