On Mar 2, 2014, at 5:05 PM, Will Harris <[email protected]> wrote:
> I'll take a shot at answering some of the questions in a general way: > > The bits and pieces= > > Gelcoat - gives a finished outer surface and makes the part easier to get out > of the mold > > Fibers - The fibers are what give strength to the part. The engineers have > gotten very clever to matching the type, amount and orientation of the fibers > to realize the best strength to weight ratio > > Resin- The resin is only there to hold the fibers in orientation. Resin does > not add strength on its own really. > > Core- The core separates two thin skins. The skins can be a lot lighter, and > stiffer working together across a core. > > A good laminate- > > A good laminate comes from: > > Good engineering. Really, this is the key. After it, it is just execution. > Getting the right fiber, orientation, resin, resin ratio, Core and cure is > probably 80% of the game. If you have a crappy recipe, you get a crappy > cookie. > > Fibers - There are a few basic fibers used commonly in boatbuilding. Glass, > Carbon and Kevlar. There are all sorts of different types, weaves and > delivery systems with in each group. Kevlar is receding in popularity. > > Cores - There are 3 main cores - Balsa, foam, honeycomb. Basically, they go > in that order for both cost and performance. The core needs to be strong > enough to resist the sheer forces of the two skins trying to go opposite > directions. Most of the time when the Volvo boats have big delam issues, it > is because the core sheered. The right thickness of core is important. Too > thin, the boat will not be stiff. Too thick, you add weight and $$ for > nothing. > > Resins - Polyester, Vinylester, Epoxy. Again, performance tracks price! > Poly is cheap. It is the most brittle too. Epoxy is awesome stuff. One of > its best properties is that it is the most flexible. Sounds > counter-intuitive but that is good. In poly, little microscopic cracks form > because it is brittle. This lets the fibers move a little in relation to > each other and the boat gets softer overtime. > Vinylester is right between. We like it a lot because it shares many of the > good properties of epoxy, it easy to work with and is a bit less expensive > than epoxy. A bonus is that Polyester gelcoat sticks to it just fine! > > Resin to Fiber ratio - Too much resin in the laminate is a common issue. It > seems like you would just slather it in there, but you'd be wrong. Each > system has an ideal resin/fiber ratio. Too much resin does two things; 1- > Adds weight- remember, resin is not very strong. 2- makes the laminate > weaker! Remember those micro-cracks. The are cracks in the resin. We want > the fibers nice and tight with just enough resin to hold them in place. > > Compaction- As discussed a second ago, we want the fibers nice and squished > together. Air voids are hard to eliminate, but must be minimized. They > weaken the laminate a ton. > > Building Process - Wet lay-up, infusion, pre-preg. Again in $$:performance. > Assuming we are using female tooling. In wet layup, the cloth is put in the > mold dry and wet out and compacted with rollers. Fast simple cheap. Your > boats were made this way. > > Infusion- In the infusion method, all the fiber, core etc are put in the mold > dry. Then we stick a vacuum bag on it with very strategically placed resin > inlets and exhausts. We draw the vacuum, and get the laminate really firmly > consolidated. Then, a metered amount of catalyzed resin is introduced > through the ports. Getting the ports place right is really important to draw > the proper resing front through the part. When the correct amount of resin > is injected, the vacuum stays on until the part cures. This gives us really > good control over both the resin ratio and the consolidation. > > Pre-preg - carbon comes from a laboratory with a heat setting epoxy already > in the fiber. This is placed in the mold, a vacuum applied and it is cooked > in a oven. First, the heat melts the glue and lets it flow. Then the heat > is kicked up a notch and that sets off the cure cycle. There is a really > specific protocol for ramp up, cure and ramp down temps. If you really like > spending, the oven can be an autoclave with increases the pressure to about 6 > ATM as opposed to the 1 possible with an ambient bag. > > This is the highest performance option, but stupid spendy. Our little 30 > footer could come out a the $330 - $400 K range. Ouch. > > That is a short ( for an overview), but long ( for a mail list ) run down of > modern boat building. If you have specific questions; fire away. > > Come to the Open House! We will be running infusion demonstrations, and the > smart guys will be able to explain anything to you. Plus, you can heckle > Andy and get a free lunch. > > Will > > > > > > > -- > Will Harris > Waterline Systems > > 716-531-6088 > > > _______________________________________________ > This List is provided by the C&C Photo Album > http://www.cncphotoalbum.com > [email protected] _______________________________________________ This List is provided by the C&C Photo Album http://www.cncphotoalbum.com [email protected]
