Question on Composite layups?

General Composites Discussions Composites Talk
#1

Had a very simple qustion I hope for I am new to composites…
How much resin to cloth weight(per sq. yard) ratio should one expect to use in a composite layup?
Thank you
sailfish

#2

Unless you advise of the materials you are going to be using, its a very difficult question, thats really impossible to answer.

#3

CB is right as it used to be 50% to 50% (hand lay / VIP) but now with Epoxy resins and CF Pre-pregs maybe 30% resin to 70% reinforcements.

#4

Is there any disadvantage (beside the extra weight) for using to much resin?

#5

Non. Just extra weight. It is the combination of the reinfocement material & the resin matrix to get the lite weight and strength…try looking up the word Composites in a dictionay.

#6

well yes there is, not only are you adding more weight, but adding alot of extra brittle material inbetween layers of laminate. The more brittle material the more chance there is that de-lamination can occur. It also will not be nearly as strong as a properly proportioned laminate.

#7

…also more money too!:rolleyes:

#8

Does anybody know the resin/re-inforcement ratio of a typical carbon pre-preg? (like ACG MTM 250 deg cure or similar)

#9

I’d have to look it up but as stated above: “…CF Pre-pregs maybe 30% resin to 70% reinforcements.”

I have a 6+ hour drive ahead of me today (picking up a full size '63 Ragtop VW Bug body and door molds) , so type at everyone tomorrow.

#10

Classic Bike,

I will be using 6 oz fiberglass and 1 layer of 4oz so I don’t get print through for my layups and it will be 3 layers of 6 oz & 1 layer of 4oz done all at the same time, one after another.

I am making rc sailboats using a split mould that I will produce. The sailboat will be 73 inches long and have an 11" beam.

Any help would be well appreciated…

Thanks,
sailfish

#11

If you are new to laminating then its pretty certain that you are going to use a little too much resin, in your early work.

However on something like you are making this isnt likely to make a tremendous amount of difference.

I would say laminate using a brush, and if you dont have a lot of experience of the process let the tissue layer, and first layer of CSM harden before finishing the job with your last 2 layers of CSM.

Finally dont make the mistake of thinking that an overly thick lay-up is going to increase strength…it very often doesnt have this effect, and only adds extra weight.

#12

Classicbike,

Thank you for the advice, I will definitely keep it in mind when I go to produce my first boat.

Thanks,
Sailfish

#13

Low cost can be 20:80, standard is 60:40.

Our 120Eglass from Bryte and 5.7oz plain weave carbon from Newport is 50%. Our CE Astroquartz is 38% resin.