Warren,
I have 40+ years of experience  in  creating composite products in another industry unrelated to carbon fiber or fiberglass. My composite materials included thousands of constituent parts and materials. And while most of the materials were commodities, we had no luxury of storage space so we ordered the correct amount to finish the job and not have leftover materials that would become waste.  So, I come from a different background that makes it hard not to look for well crafted formulas that are not based on rules of thumb.  I and my competitors were able to control our materials so well that we never had to go back to the well or as you call it topping off the resin pot.  It was so unprofitable to reorder materials to be shipped to the jobsite that it was part of our ethos to never order less than needed, and never order so much that we would throw away anything. Material variances were typically within 1.5% for my projects. Only a few selected sub assemblies had waste factors approaching 5%. So, forgive me for looking for tighter formulas. It is in my nature. I will adjust my thinking to conform to the  carbon fiber materials and processes.


A Lifelong Learner

Different people will have different rules of thumb that work for them either developed through experience or passed down to them so it is kind of often the case where there are no set answers.  A number of different things will work.  With infusion, you don't want to have too little resin.  Sure, as long as you have plenty in stock, you can keep topping up the resin feed jug, but if you run out completely you may ruin the part!


Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

Thank you Warren.  I am hopeful that others may be able to chime in here with what their experiences are for other products and materials. As old as the composite industry is, I am a bit dismayed that there is not more data available for the full spectrum of available materials. I did not realize I was getting in on the ground floor.


A Lifelong Learner

John our mesh is only a medium mesh so  we wouldnt have data for other mesh speeds. Other mesh speeds are likely to have different uptakes and waste - although waste is typically the lines an jug than the mesh which is accounted for in its own right.

Other core materials you will need to test or get manufacturer data.




Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

For fibre reinforcement it is pretty simple: let's say you want to achieve 60% fibre content in the fibre layers. You take your cloth weight, and calculate the volume of the fibres using the density. ÷60 x40 and you got the volume of the resin. For hybrid cloth you have to assume the volumetric relation of the two types of fibres. A bit more work, but basically the same. For better understanding, given the same cloth weight and resin content, glass uses less resin than carbon, and carbon less the aramid. Hybrid is between carbon and aramid. For core materials you have to either experiment yourself, or use given data for the resin uptake. Same for flow mesh. Different mesh consume different amounts of resin. But is doesn't make a difference whats under the mesh. It's just a layer like everything else when it comes to resin consumption. For thin parts the flow mesh usually takes more resin than the parts itself. That's a fact you have to life with. At lest with resin infusion.

Warren,
You are getting me closer to understanding this, but when you write: "the amount of resin used by the mesh which is 700 grams per square meter of laminate, regardless of thickness" are you describing thickness as the thickness of the reinforcing fiber, or the thickness of the resin flow mesh? Which resin flow mesh? I would think that each different flow mesh (slow, medium, fast) would each have their own waste factor for resin usage. Right? or Wrong?
And, I am considering using hybrid materials that include an aramid along with carbon fiber. In other cases, I am thinking I want to use pure aramid and not CF and a few variants of CF and aramid layers.  I am still unsure that I have all the raw data and formulas needed to understand and calculate each of those combinations and then also include different core materials like Lantor Soric or End Grain Balsa.  And related to the End Grain Balsa, I cannot find solid data about resin uptake of the end grain and how best to control the weight gain when the balsa becomes resin rich. If I try to seal the balsa end grain, what weight will the sealer add to the final composite? Can I control the uptake of sealer by the balsa end grain if I were to use glass bead, or other additives to the sealer? I just cannot find that kind of data anywhere. I have read on one of the manufacturers (or distributors) websites that their resin usage formula is so simple as to add a 75% waste factor. Does everyone throw 40% of their resin away when they throw away the vacuum bag and resin flow mesh? I could be throwing away a few Kg of resin.


A Lifelong Learner

With Resin infusion you are normally looking to achieve a 60/40 fibre/resin ratio, this means for every, say, 100grams of cloth you will need 66 grams of resin, all of the reinforcements are listed by weight e.g. carbon fibre 2/2 twill 200gsm, the 200gsm refers to the actual weight of the fabric in grams per square meter, so 1 square meter of this cloth will need 133g of resin to achieve the 60/40 ratio. You also need to account for the amount of resin used by the mesh which is 700grams per square meter of laminate, regardless of thickness. Another 100grams of resin will be required by the feed lines and in the bottom of the feed jug. Here’s an equation that can be used for this;


The table  (which is  from the previous guide):


For different kinds of mesh, the manufacturer should be able to give you an indicative  figure for resin calculations.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

In a very old topic, the calculations for resin usage were address by Paul Statham in a chart. THANK YOU Paul! But until I saw this topic, I had not seen any data for the infusion mesh and how much resin must be prepared and used for the mesh. I expect it is different for each type of mesh, but where is this data found? Is it typically listed under the specs for the mesh?
Also, Paul  wrote that there was a formula  for calculating the resin usage, but  all I saw in that topic was the chart and no formula. Can someone point me to a complete formula?


A Lifelong Learner