Hi Philip,
Thanks for your email and sorry for the delay in getting back to you. I was checking through some old emails and noticed that I hadn’t replied to you on this. it sounds like a very interesting project you have there. you should only run the mesh of the reverse side, you will come across a few issues trying to run is against the tool as well. you will need to drill (or punch) the foam to get resin flow to the tool-side, I would recommend 2.5-3mm holes every 20mm in the foam this should allow reasonable flow-out into the fibre. you can run peel-ply against the tool no problem so your stack would look something like this:
Bag
Mesh
Peel-ply
Carbon
Drilled foam
Carbon
Peelply
Toolface
Calculating thicknesses and consumtion is quite easy. Generally resin infusion (VARTM) will produce a thickness that in millimetres is 1.25 times the cloths weight in KG so a 200g cloth is 0.2kg, which means, 0.2 x 1.25 = 0.25mm in thickness. Here’s a quick outline of the approximate laminate thicknesses of the most popular carbon fabrics.
1k 90g – 0.11mm per layer
3k 200g – 0.25mm per layer
12k 650g – 0.8mm per layer
Resin quantity;
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;
Quick reference chart for resin consumption in infusion;
Number of plys of 200g cloth
1
2
3
4
5
6
7
8
Area Of Part In Square Metres
0.1
183
197
210
223
237
250
263
277
0.2
267
293
320
347
373
400
427
453
0.3
350
390
430
470
510
550
590
630
0.5
517
583
650
717
783
850
917
983
0.75
725
825
925
1025
1125
1225
1325
1425
1
933
1067
1200
1333
1467
1600
1733
1867
1.25
1142
1308
1475
1642
1808
1975
2142
2308
1.5
1350
1550
1750
1950
2150
2350
2550
2750
2
1767
2033
2300
2567
2833
3100
3367
3633
2.5
2183
2517
2850
3183
3517
3850
4183
4517
3
2600
3000
3400
3800
4200
4600
5000
5400
I hope this helps,
Best Regards
Paul Statham.
Carbon Mods/Easy Composites
Unit 39 Parkhall Business Village
Parkhall Road
Longton
Staffordshire
ST3 5XA
( +44 (0) 1782 324000 | fax. +44 (0) 1782 596868
:
www.carbonmods.co.uk |
This email address is being protected from spambots. You need JavaScript enabled to view it.
From: Philip Lardner [
This email address is being protected from spambots. You need JavaScript enabled to view it.]
Sent: 08 November 2011 12:30
To:
This email address is being protected from spambots. You need JavaScript enabled to view it.
Subject: Vacuum infusion questions
Hello,
I need to make a number of large composite foam-cored panels using vacuum infusion rather than wet lay-up vac bagging. The panels will be made up of 5mm closed cell PVC foam board (cut to various shapes) with a single layer of carbon on either side, wrapped over at the edges.
My question is - do I need to use a layer of infusion mesh on both sides of the panel/stack or just a single layer on top? It is not important that the completed panels have a polished finish - in fact a peel-ply finish is preferable as other parts will be bonded to the panels later.
Stack #1:
Vac-bag film
Infusion mesh
Peel-ply
Carbon cloth
5mm Foam core
Carbon cloth
Work surface/table top
or Stack #2:
Vac-bag film
Infusion mesh
Peel-ply
Carbon cloth
5mm Foam core
Carbon cloth
**Peel-ply**
**Infusion mesh**
Work surface/table top
Second question - is there a way to calculate (or just reasonably estimate) the volume of epoxy mix required to infuse a given area of carbon cloth?
Thanks,
Phil Lardner.
