Questions on eb700 tooling board

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Questions on eb700 tooling board

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quinn	q quinn posted 6 Years Ago HOT Topic Details
q Group: Forum Members Posts: 155, Visits: 992	So far having bad luck with high temp tooling. Mostly issues with post curing off the plug causing surgace issues. Anyway, out of fruatration im ready to just machine some solid molds. The price isn't all that bad considering what I've spent so far on high temp surface coat and epoxy. So I watched the video on this tooling board and it says it's great for master patterns and can be used directly as a mold for "small" production runs and prototyping. What exactly does this mean? I'd like to mill a mold directly into this stuff and get some decent use out of it. Will it not last long with repetitive use? How many pulls will I get and what happens when I get beyond that point? Will it be ok for maybe 50 parts or so? Maybe recondition with more s120 at that point? I'm also finding it very difficult to get a pinhole free surface in prepreg with vacuum bagging. Also not really happy with the wrinkles on the inside of the part. Needs to have a not so horrible surface in there. I'd like to solve both these problems with either a custom bladder or expanding silicone, but I'm not sure what this tooling board will hold up to. It will be a 2 peice mold, similar shape to football, each half milled out of solid block of tooling board with minimum wall thickness around 25mm. Will the mold hold up to some decent pressure? Nothing crazy, maybe 25 psi, just need a bit more than what you get with vacuum. I realize my other option is to mill a plug from the tooling board and that would solve my problem of post curing mold off the plug since the tooling board can handle the post cure, but I would still prefer to skip all that mess and mill a mold directly since I know nothing can really go wrong. Less work and no dealing with surface coat and lay up.
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quinn	q quinn posted 6 Years Ago HOT Post Details
q Group: Forum Members Posts: 155, Visits: 992	+x Lester Populaire - 3/4/2019 3:54:03 PM yeah i know the frustration and wish i could give better advice to others, but there are just a milllion little things to think of and little differences between products. What you describe sounds like the glass transition temperature of your resin was not high enough. This can be because the post curing was not sufficient, the resin system cannot get a glass transition temp which is high enough, or the part got hotter than the oven temperature during curing due to thermal runaway. With the thin walled canopy you are making the last one is certainly a non issue. I don't know the system you are using to make your moulds, but it is very well possible that 3h post curing is not enough. i am using a mould resin that needs 10h at 120°C to get the maximum glass transition temp. with ramps this takes more than 24h, which is rather annoying... So double check that. Furthermore i would stay at least 20°C away from the Tg while curing. But I'm sure you could bake your prepregs at lower temp. than 120°C? cheers, Lester Ok, maybe my post cure wasn't long enough or hot enough. My prepreg is specd at 120c cure So I don't think I can go lower, however I could go higher with the post cure on the mold. I didn't really know how much higher the post cure needed to be so I stopped at 130c assumining it was enough. Sounds like not the case. All that being said, tooling prepreg mold on tooling board plug sounds like a pretty attractive process so I might go that route for the next attempt. I need to order the tooling board from easy composites anyway so I can get some of their tooling preg. Would you say the prepreg mold is an easier process and less likely to go wrong? Aside from my post curing issues, I still had a hard time avoiding tiny air bubbles in the surface coat. It was better on the second try but not completely void free. I would rather avoid surface coat completely and do a prepreg mold if you think it's a more reliable process with less chances for things going wrong.
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