Laminate Thickness

General Composites Discussions Engineering Talk
#1

Kindly suggest any online or downloadable laminate thickness calculator.
Im working with E-Glass Fiber and Polyester Resin

Thanks

#2

Here is the excel spreadsheet that I made. You are welcome to use it. It’s rather convoluted in it use of the units of measurements. I typically work with ounces/yard^2 rather than grams/meter^2. I often use grams when measuring resin but I use yards^2 when working with fabrics. You will also see fun things like grams/square yard. :smiley: You could edit the formulas to work with meters if that is needed.

#3

Thanks a million…You are a life saver :smiley: :smiley:

#4

Take a look at this:

material calculator

#5

I’m going to resurrect this one.

Question regarding laminate thickness. In spec sheets of fabrics I typically see a thickness noted, .010" thick or whatever. Typically I make a sample to figure out the thickness of the laminate for the given process that I’m doing because the end thickness seems to very a bit. So my question is other than making a sample is there a sure fire way of figuring this out?

I’m just using a vacuum bag with post cure. For something like a pre-preg carbon cloth should I assume that the vacuum is going to compress the fabric thickness from .010” to, say .008”?

I need to figure this out before I order material because the product end thickness will determine how many layers I need. This is a special material with large minimum order so making a sample isn’t an option.

#6

There is no sure-fire way unless you are very familiar with the process, fabric, and resin. Obviously, the pressure applied makes a difference but what really makes a difference is the resins ability migrate out of the laminate as the fibers are pressed together. If the resin can’t get out the fibers can’t get closer together. Resin viscosity, temperature ramp rate (prepreg), and bleeder material all play a part in letting the excess resin escape from the laminate. Even the vacuum bag material can play a part.

You can calculate the thickness if: 1) The fabric areal weight is accurate, 2) The laminate Vf% can be predicted, 3) the laminate porosity can be predicted.

I document the calculated Vf for nearly every part that I make. This documentation builds experiential knowledge that helps predict the weight and laminate thickness of future projects using MY techniques.

Maybe you can contact the prepreg manufacturer to see what kind of Vf% they got in their test samples. You can use this info to to predict your thickness.

BTW, I’ve seen some fabrics go from .016" to .009".

Adam
Who wishes he could be more helpful…

#7

Thanks Adam. You confirmed the conclusion that I’ve been arriving at. With so many variables its going to be hard to know. I’m going to have to make an educated guess on the end thickness (layers) then base my order on that. Then I’ll do a test panel or two to verify before I commit to finished parts just to be sure.

#8

Adam is totally right (he usually is). Only when you can predict Vf and void ratio, and when aerial weight is correct, you can predict an exact thickness. It is just science, and you cannot beat that.

Can the supplier help you with figures they arrived at, using techniques that you can use as well?

#9

The materials kinda odd so they can’t give me great answers. If it was something more mainstream like 2x2 twill this would be easier. I’m just going to make some educated guesses based on the information that the supplier can provide and what I know about my own system to come up with my numbers. If I do it right I should be close. Thanks for the guidance guys!