Balsa Core Print Through

General Composites Discussions Composites Talk
#1

Hello,

Thanks for stopping by. I recently laid up my first infused part and found that with 6 layers of 199 gsm cf, my part is still not to the stiffness that I would like. I figure the best way to get the stiffness that I want would be to use a core material. I chose to get some 1/4 balsa core since my part will not be anywhere near water and its pricing is reasonable. I would like to infuse this part, but I am concerned that the pattern on the balsa may print through the outside layer. I plan to use 3 layers of 199 gsm for the outside layer and 2 on the inside. Now if it wont print through and 3 layers is ok to use, what would my layup be like?
3 layers cf
1/4 balsa core
2 layers cf
peel ply
perforated release film
flow media

Or would it be best to infuse the outer layer then infuse it again with the core and the inside layer?

Thank you so much for the help. I wouldn’t even been able to get this far with out this forum.

#2

its a good chance you will see a line where the core ends. Usually it creates a little distortion in the fiber print and shows a line. Also depending on the balsa groove size and curveture of your part this could also cause printing. If you do core as a second step it will eliminate the printing however it is much more work. You might want to look in to foam cores such as PET or SAN as they are usually cheaper than Balsa and perform very well.

#3

PET might be cheaper, SAN is definately not cheaper. Unless ATC/Gurit does another sell out of their thin sheet inventory.

However, infusing the way you propose does not work. The speed of the top and bottom layers differ too much. Also the block size (1"x2") of the balsa is a bit large for the flow speed of the bottom layer (which is very slow)

I have no idea if the part is weight critical, or stiffness critical. What are you trying to achieve? Can you elaborate?

#4

Hey Herman,

I read somewhere in this forum that others have imprinted their cores with chicken wire to help the flow. Would this work? Or should I just look into doing a two step process.

As far as what I am looking for in my piece, I would like a very stiff piece. The weight is not as much of a concern for me,but I dont want it to weigh a ton either. Every gram isnt being counted here. I would like to keep the piece roughly 1/4 thick. I plan to glue to some wood to the edge of the piece, which is why I kind of thought balsa would be better to use for gluing wood to the edge. The thing I am attempting to make is a “S” shape that is 15" wide by about 24" long. Imagine the if you were to extrude an “S”. This going to be a component to a piece of furniture so I want it to be very STIFF. I couldn’t find any data comparing 1/4" core`s stiffness side by side. I just assumed that the balsa would be the stiffest.

I really appreciate the responses Hojo and Herman. Thanks!

#5

OK. So we have a sort of lightweight part, but nothing extreme. Infusion, carbon, 1/4" thick.

I would say: Use Lantor Soric as a core material. Although balsa is stiff, it also creates a lot of problems in your setup. I would trade the balsa for Soric, and accept the slight weight gain.

#6

Exactly! I am having a hard time sourcing 6mm lantor soric xf. Do you know of any suppliers I can get a few yards or so from?

Thanks!

#7

Not in the USA. I suggest working your way down from the supplier/manufacturer.

In the USA Baltek is the importer:

U.S.A.

Baltek Inc.
Baltek Inc.
P.O. Box 16148
High Point, North Carolina 27261
Office/Plant: 5240 National Center Drive
Colfax, NC 27235, USA
Phone: +1 336 398 1900
Fax: +1 336 398 1901
E-mail: corematerials.americas@3AComposites.com
Website: http://www.corematerials.3acomposites.com/america.html

Ask them either for a sample, or ask who might be selling in small quantities in your area.

If you would be living in the Netherlands or Belgium, you would have no trouble… :slight_smile:

#8

I have had great luck curing pint through by using veil material. They make some thick veil that will take most of the normal print through out of the stackup. groves in core will usually show up but not as pronounced. Also try using a different weave or layup orientation in your stackup. That may also reduce your print through from the core material.