Resin intake

Discussion in 'Fiberglass and Composite Boat Building' started by Sailcy, Nov 30, 2016.

  1. Sailcy
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    Sailcy Junior Member

    Could anyone experienced help to understand how to calculate accurate resin intake when infusing foam composite panel please.
     
  2. groper
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    groper Senior Member

    surface of 80kg/m3 divinycell foam absorbs 300gr /m2 (resin to fill surface porosity)
    wet out of stitched e-glass reinforcements - multiply the weight of glass x 0.32 @ 100% vac.

    Other types of fabric such as wovens etc will use a different amount. You have to test infuse and weigh the result for different reinforcement types. Same goes for your flow media if using any. If using grid scored and perforated foam, multiply out the volume of the flow channels and perforations per square meter - an excel spreadsheet works well to automate all these calculations.

    Add in other consumables such as peel ply ~ 80gr/m2 and all your resin lines etc.
     
  3. Sailcy
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    Sailcy Junior Member

    Also, I've been told that resin weight will be approx equal to the fabric used. For example, if design called to use 600gm both sides of the foam panel the resin intake will be roughly 1200 g/m2. (1.2 L) Anyone disagree?
     
  4. Sailcy
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    Sailcy Junior Member

    Just as a reference. When I used to build a plywood boat I've done some experiments to carefully measure (expensive) epoxy consumption. As a result was the figures of 1.5 liter per 1 sheet of plywood 1.22 x 2.5 m. Glassed inside and fiberglassed outside using 200 gm fabric. So to set up the target figures is make sense imo to stay within budget. Appreciate to see other builder's figures.
     
  5. TANSL
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    TANSL Senior Member

    The weights ratio of resin/fiber can range from 60/40 (manual lamination, not very careful) to 35/65 (infusion).
     
  6. groper
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    groper Senior Member

    That is pretty close for that layup as you have 600gr for the surface porosity of the foam, 1200x.32= 384gr for the glass, 160gr in peel ply, plus whatever your using as flow media.

    The problem is how much will you use for a different layup? Hence you need to calculate it rather than just say "equal weight in glass" refer to my first post...
     
  7. Sailcy
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    Sailcy Junior Member

    Thanks Groper!
    Now I have some idea/guidance of what approx resin consumption is expected
     
  8. fallguy
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    fallguy Senior Member

    small hijack sorry sailcy

    Sailcy and I both post on Wood's forum, so hopefully he won't mind my thread hijack. I'd like to find a way to chat with Groper. I just want an opinion about something boat related. I'd rather not post it publicly if possible. Thanks to both Groper and Sailcy and hope I'm not violating a forum rule. I really like this forum.
     
  9. rxcomposite
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    rxcomposite Senior Member

    The 50/50 glass to resin ratio by weight is for hand layup only on woven rovings (WR) and it works only on the target or designed ratio on the laminate only. In infusing, it could go as high as 75/25.

    It becomes complicated when you use a different fiber such as CSM which can go 33/67. There is a formula that can be used to predict the ratio for different fibers to be used. Other types such as Uni or stitched Biax have different designed ratios.

    Combining with other types of materials such as felt, foam, or plywood, the other material absorbs resin in varying degrees so you have to add that to the predicted consumption.

    So when infusing, the 75/25 Gc ratio can be used for a start THEN add up the resin to be consumed by the surface of other material such as foam or plywood. That will be your laminate weight.

    For real resin quantity in infusing, you have to add up the fudge factor or the consumables which will not be part of the laminate weight. These are the the resin that will be absorbed by the;

    1. peel ply
    2. the resin absorbed in the bleeder material
    3. excess resin trapped in the feeder lines

    Hard to predict but a 20% plus resin would be a good start or the figures posted by Groper would be a good starting point in calculations.
     
  10. Sailcy
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    Sailcy Junior Member

    Fallguy, you can use this thread as long as you wish. Glad if it can help you with your searches. Definitely no complaints from my side. Best Wishes!
     
  11. groper
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    groper Senior Member

    Just send me a private message mate :) click my name and follow the prompts...
     
  12. Sailcy
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    Sailcy Junior Member

    Thanks rxcomposite and TANSL!
    Also, it will be nice to see if someone shared real figures based on the project experience. For example boat type, length, displacement, surface area infused, volume of resin used, what sort of core/fabric used. The reason behind these questions is that my experience shows that designers usually publish very conservative figures regarding the amount of resin needed for the project.
     
  13. fallguy
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    fallguy Senior Member

    I did this and hit a dead end on several attempts.
     
  14. Sailcy
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    Sailcy Junior Member

    Sorry rxcomposite,could not connect in my mind the resin vacuum infusion and a Volvo Penta exhaust system. What is it for?
     

  15. ondarvr
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    ondarvr Senior Member

    A few years ago I was doing infusion demonstrations frequently, this meant figuring out how much resin was going to be used on a part I'd never infused before.

    I normally just used the 50/50 glass to resin weight ratio on a cored laminate, this allowed for the core and waste, I always had a small amount of resin ready to be catalyzed at the last minute. It was rarely off by much though. But, there are so many variables involved with each laminate schedule, and how well the core was cut, whether it was grooved, perf'd, on a scrim, thickness, Vacuum pump, etc, and then how well the glass and core was placed in the mold, that until you made a few parts and dialed it in, you didn't have an exact figure.

    We would compete and place bets on who could get closest on how much resin was used.
     
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