RTM VS. Hand lay-up

Discussion in 'Fiberglass and Composite Boat Building' started by Kovaceski, Oct 6, 2006.

  1. Kovaceski
    Joined: Oct 2006
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    Kovaceski Junior Member

    Hello group, can anyone tell me some link where I can compare the costs and the threats bedween RTM and Hand lay-up?
    Thanks.
     
  2. apprentice
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    apprentice Junior Member

    RTM please explain
     
  3. Kovaceski
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    Kovaceski Junior Member

    RTM (Resin Transfer Mould)
     
  4. apprentice
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    apprentice Junior Member

    cool thanks couldent rember for the life of me what RTM stood for.

    i think you should go with hand layup method i just believe you have greater controll of the finished product than resin transfer. i work fro haines signiture and we still use hand layup quite often. but thats just my spin on it
     
  5. Kovaceski
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    Kovaceski Junior Member

    I can't stay on Hand lay-up. If I do that, I will lose my client. My plant is located in a small city and it's very hard to find qualified workers. On the other side, I have to diliver 70 to 80 boats per year to my client. He is already preapering a new model for the next year and therefore I have to do something to speed up the production. I hope you understand my problem.
     
  6. apprentice
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    apprentice Junior Member

    do you have moulds for your boats because if u do you could use pre preg or wet preg to lay up your boats with
     
  7. Kovaceski
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    Kovaceski Junior Member

    yes, I have molds (for open molding). But, what is "pre preg" ; "wet preg".
     
  8. apprentice
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    apprentice Junior Member

    pre preg is a form of chopped strand but it is pre inpregnated with hardner and resin what you do is lay it in the mould apply heat and it cures the disadvantage is that u dont have a long shelf life with the roll of reinforcement unless u have the ability to refrigdeate it

    wet preg is another form that is used on large boats down here it is a roll of reinforcement (any type) and it sits on a roller the motorised roller then pases the reinforcement through two other rollers that pass through a tray of resin this enables you to do large areas at a time u only need two people to guide the wet reinforcement on to the mould and another two to roll it out
     
  9. Kovaceski
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    Kovaceski Junior Member

    ok. I have visited some links (conected to wet preg and pre preg) on the net. I have to say that it is still dirty work but, it is better than hand lay-up. I will read more about it and I will consider the possibility on applying it.
    I just want to ask one more question.
    Do you have any experience with RTM technology? Because, (to be honest) it seems to me that there are some "hiden" problems or extra costs behind all those presentations.
     
  10. Pericles
    Joined: Sep 2006
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    Location: The heights of High Wycombe, not too far from Rive

    Pericles Senior Member

    Hello Kovaceski,

    http://www.proboat-digital.com/proboat/200610/ has to be the first place you look.

    Yesterday, I received 2 samples of a E-glass fabric called ParaGlass 22 3D. http://www.parabeam.nl/Product/Index product.htm

    One sample had been infused with resin and the other in its natural state. It is a fabric woven out of a 100% E-glass yarn and consists of two decklayers bonded together by vertical piles. These piles are woven into the decklayers thus forming an integral sandwich structure.

    The fabric is infused with a thermoset resin, the fabric absorbs the resin and due to the capillary forces of the piles, the fabric rises to the preset height. In this one-step process a lightweight and strong sandwich laminate is formed that offers excellent mechanical properties. Parabeam® can be used for many applications in the composites industry and offers multiple advantages against traditional sandwich materials or solid laminates.

    The process is only really suitable for hand layups because vacuum bagging would prevent the fabric expanding, but the boat created would be lighter and stronger than other core materials. The nearest supplier to you is in Slovenia,
    but it was Sandra Coulthurst http://www.univar.co.uk/downloads/Parabeam_for_yachts.pdf who sent me the samples. Contact her sandra.coulthurst@univareurope.com

    You will discover the ParaGlass is a material that should allow you to continue building boats without RTM. There are a number of thicknesses up to 22mm. My cured sample is 150 mm x 100mm x 22mm. I weigh 120Kgs and I stood on the sample with all my weight on one foot. No change to the structure. :D I plan to build my boat with ParaGlass, marine ply and epoxy.

    Good luck,

    Pericles


    Slovenia supplier:
    SPS d.o.o. Mr. S. Podbevsek
    Neveljska pot 23
    1240 Kamnik
    Slovenija
    Phone: +386-(0)1-8397384
    Fax: +386-(0)1-8397385
    E-mail: mailto:podbevsek.sps@siol.net
     
  11. MarshallT
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    MarshallT Junior Member

    Kovaceski
    I think what you are looking for is Vaccum infusion instead of RTM. With RTM you need 2 molds (male and female). This is good if you want to have a part with 2 good surfaces (inside surface and outside). RTM can be used for larger production runs since the tooling costs are high. There is another version RTM Light which uses composite tooling instead of metal tooling but you still use 2 molds.

    For Vacuum Infusion you can use standard female molds as long as they can hold a vacuum. It is very clean and consistent as long as you pay attention to details and do not cut corners. With a bit of practice you should be able to easily do 80 boats a year. What size is the boat? I don't think it wil speed up your production. It may make it easier for you to get better workers since it is a clean process.

    As for the Paraglass this material was developed for double wall tanks and is not meant to be used for boat hulls. It will not be a good laminate since the tranverse fibres keeping the 2 layers seperated will not be able to handle the shear stress.

    FYI: If you vacuum infuse the Paraglass until you get the resin to wet out the fibres then you can release the vacuum. It will have the correct amount of resin and will spring up the same as in hand layup. This is a good technique to make heated molds (you flow hot water between the 2 layers)
     
  12. MarshallT
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    MarshallT Junior Member

    Kovaceski
    I guess I didn't really answer your original question. I will try to give some info assuming what you are looking for is Vacuum Infusion (VIP)

    In general the cost is the same for VIP versus hand layup. Of course this is a general statement but from what you are saying if you need to switch then I doubt cost will be a barrier. In the begining the cost may be higher but that is woul happen any time you make changes. With VIP you will use less resin so you will save there but on the other hand you need a vacuum bag so that is an additional cost.

    There is a learning curve but there are now a lot of people and companies who have a lot of information. Unless you have a very difficult project or circumstances you should be able to get there easily.

    I feel the biggest advantage is in consistency. With hand layup you need to rely on the person applying the resin (too much or too little??). If you have a core did they wet it out enough and is it well bonded?? With VIP you will know if there was a failure. With a proper procedures hopefully you will not have failures. Some companies are doing 100ft and longer hulls by VIP so you can be sure they cannot have failed attempts very often. There are some good examples in Professional Boat Builder magazine which is availalble on line.

    If work force is a problem you can look into precut laminates. The complete laminate will arrive in boxes labeled and ready to apply. You can also get the vacuum bag made for the size of your hulls. You will have check to see if either is availalbe in your area.

    If you want to email me more details of your boat I can try to give you a better answer.
     
  13. fiberglass jack
    Joined: Dec 2005
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    fiberglass jack Senior Member

    go with rtm lite , and use a silacone bag , if u are going to be building 70 to 80 boats the silacone bag will save you time and money in the long run. i see your problem with workers hard to train them for this system, the oldtimers love hand lay up and are hard to teach, read as much as u can on resin infusion its very simple
     
  14. Kovaceski
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    Kovaceski Junior Member

    Dear MarshallT & fiberglass jack

    Is the resin influsion same as VIP method? I call that vacuum bagging.
    If I use those methods, will I have good quality of the surface without spending so much hours of laminating and “decorating” the surface?

    fiberglass jack
    You mean to use silacone bag as female mold? That will be more vacuum bagging than RTM Light. Am I right?

    If I use vacuum bagging, can I produce deck part as well? Because If I can’t, I still have to laminate by hand lay-up and I will still have same problems (mainly with the surface).

    The model of the boat I’m producing is 4.20 meter long. But, that’s not the only product we are producing (we produce tanks, insulation panels, public equipments and some other products as well).

    In the normal terms, production of 70-80 boats shouldn’t be some problem. But, with my 15 workers (only 5 of them can laminate) that is my maximum. On the other side, my plant is 4.500 m2; we are using 1/3 of the space and we work only one shift. And that is the shame. Therefore I’m looking for new method where I can seed up the production with minimum qualified workers. After that, I can easily find workers for the assembling.

    One thing fears me with vacuum bagging. On JEC Show in Paris, I was on a presentation of vacuum bagging method. After the presentation, many people came to speak with the presenter about their problems with this method. I was just listener there, but I’ve understand that dry areas and leaks are real threats with this method. That was the main reasons for me, to start thinking about RTM or RTM Light. There, after you invest in the mold, you don’t have problems. Or, it only looks like that?!
     

  15. Richard Hillsid
    Joined: Mar 2006
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    Location: Scandinavia

    Richard Hillsid Senior Member

    I tried the Parabeam a few years ago, it has nice potetial above waterline and in decks, or building double waled tanks, when using normal polyester i noticed i had to use a UV light and some ventalation, something to do with styrine gases geting traped, but a exelent product in the right place.
     
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