So i’m assuming that you have the reinforcement saturated with resin lay in a few layers into a mold and then with pressure on a tooling surface the reinforcements between them get shaped?
is this right?
what is different with the molds, how are the parts shaped?
what you describe would be a typical wetlayup/vacuum bag precedure. you can make a cheesed homemade prepreg, but it is the same as true prepreg
prepreg is fiber material that has a certain percentage of resin impregnated in it during manufacturing, comes on a roll just like you would buy a roll of any fabric,. it has a wax paper on one side and sometime a plastic front.stored in a freezer. and cured by a post cure in a oven, not ambient temp. you would cut it just like any fabric and stick it to the mold like a sticker. not that I recommend it, but you can actually laminate without gloves. the weave stayes together and holds a strong sharp edge. there is nothing better then prepreg that I have ever used
So if you wanted to make a prepreg mudguard for a motorcycle, can you make your typical style mold with some sort of high temp resin, or do you need some sort of mold made from metal?
it doesn’t have to be metal. As long as the mold’s materials are suitable to the temperature at which the prepreg needs to be baked then you’re fine.
well MMD just summed it all up.
A fabric with a tacky semi-cured resin.
Slightly different bagging process I think, but that might just be how I worked with it.
Molds are the same. A good sized flange, and a high-temp mold out of epoxy or metal.
Thermoplastics are the same. Fabrics are coated somehow with a plastic material (PE, PP, PU, PA6, PEI, PEEK, etc) and layed up. Unfortunatly, they are not tacky, BUT they can be repressed many times in different shapes, or just to add a layer.
It is plastic!
so once you lay the pregreg in the mold, and then pop it in the oven, what is ensuring that it holds it’s shape while curing, is there a bag placed over it and vacuum applied?
Release film on the CF PP, breather and vacuum bagged to before placed in an oven.
Think of it like tar board but you bag and cook it to final shape and hardness.
prepreg is fabric or tape pre-impregnated with resin and B-staged so its tacky, but not yet cured. You must store it in a freezer and it has a shelf life. You can layup in a composite or metal mold. Usually the composite molds are epoxy and post cured at a slightly higher temp than what the prepreg needs to cure at. Most prepreg/epoxy systems cure at 250 or 350F. You vacuum bag it like a wet layup then cure in an oven or autoclave. You must specify to the supplier whether you’re using an oven or autoclave as the resin is configured for either oven or autoclave curing. Most aerospace parts are autoclaved at 50 to 100psi as this provides a superior laminate. Its really easy to layup this stuff as its a clean neat layup and the plies stick together good, but of course its expensive and you need at least a decent curing oven or preferably an autoclave.