Bonding a pre-cured laminate to core

Discussion in 'Fiberglass and Composite Boat Building' started by groper, Jan 27, 2012.

  1. groper
    Joined: Jun 2011
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    groper Senior Member

    I was wondering about a process that i was reading about in a PDF brochure from Airex. In it, it describes a process whereby an already cured skin of resin and glass, is then bonded to the foam core by rolling resin onto the core then transfering the skin to the core and preferably using a vacuum or press to squeeze out the trapped air between the grooved core and skin until bonding is complete. The air is squeezed out and runs down the grooves to the edge of the panel or rises up through perforations in the core.

    So what i was thinking, is making up a flat panel on a melamine table to achieve a smooth finish on one side. Then make a skin only on the same said table, and let it cure with peel ply on top. Then take the panel with one smooth skin completed and bond it upside down on the skin coat after removing the peelply to acheive a flat panel with both sides finished and smooth.

    I have already successfuly done somthing similar to this on single curved developable surfaces. However im wondering if anyone has done this on compound curvature and how much compound curvature is possible before the skin cannot conform without wrinkling.

    What i was already doing, was making the skin coat using an unwaxed PE resin, then once cured doing the layup with VE ontop adding the core and top laminate before vacuum bagging the lot. Reason for doing this was to get a perfect resin rich surface on the bottom side like a gelcoat whilst incorporating a light glass cloth at the same time.

    Anyone else out there bonding pre cured laminates to core material? If so, please share you experiences and any tips/tricks or potential trouble spots VS useful applications for this method...
     
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    You can forget about a cured laminate conforming to compound curvature. Would a laminate still not properly cured, in that 'rubbery' state, take a little bit of compound curvature ? I don't know, might depend on the reinforcement and you sure wouldn't want to apply too much force to do it. Is this just for cosmetic appeal ?
     
  3. Mr Efficiency
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    Mr Efficiency Senior Member

    Just as a speculator, I wonder if there is a contact-type adhesive that would do the job ? (not with the compound curves, just joining them.)
     
  4. Landlubber
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    Landlubber Senior Member

    I wonder if there is a contact-type adhesive that would do the job ?

    ...certainly it would stick the two together, but do you want them to be structural or just cosmetic, that is the deciding factor.

    Contact will certainly hold them together, but could hardly be described as structural, as in using a resin to bond the two.
     
  5. groper
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    groper Senior Member

    You can see what im eluding to... a method of producing compound curved panels with both sides smooth from a flat table... the limitation is the amount of compound curve achievable by the stretching/skrinking available within the pre laminated skins.
     
  6. Mr Efficiency
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    Mr Efficiency Senior Member

    Have you ever seen 'laminex' taking a compound curve ? I think it is not going to be achievable, it would require the material to be ductile, or stretchable, which doesn't sound like any laminate I know.
     

  7. groper
    Joined: Jun 2011
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    groper Senior Member

    all materials will stretch a little... it depends on how much curvature you need and how flexible the skins are... the core can simply be releif cut and bogged so its the skins that will be the problem...

    One might consider making the skins on a single curved mold, then bending the already simple curve into a slight compound curve like you would do for cylinder molding... once the curved skins are made, they could be bonded to the bogged core under vaccuum.

    Another method might be to predict where releif cuts need to be made in the skins, and rebate these areas in the core. Once the cuts are made, they are reglassed over with tape only within the recessed areas which are then bogged over and only needing a small amount of fairing along the recessed tape joins. Only using peelply in the recessed areas, the rest of the panel can be made smooth off the table both sides.

    In a similar fashion to the above, one might make narrow strips of prelaminated panels with recessed edges in compound areas, taped together in position and bogged over - similar to how one would do gyprock or sheetrock plastering...

    The panels are held in position in female forma frames before the second skin is bonded which then makes the panel rigid and locks in the curvature you pulled into it.
     
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