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Matt (Staff)
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+xNo problem at all Matt! I've since used the moulds to produce some parts with XC110 which turned out well but have quite a rough feel to them due to the pinholes in the moulds haha. Won't be a problem for these initial parts as they will be clear coated anyway, but obviously I don't want to be clear coating every part when I go into production. I'm going to do another test tomorrow, this time without the warm debulk. Having thought about it, the moulds I made in a hurry turned out a bit better, and I wonder if this is because I just did a room temperature debulk for 30 minutes rather than the two hours at 30 that I did on the first two. They still weren't perfect though, so I'm unsure. Small tests under controlled conditions; even it's it's just a matter of making up some 150mm x 150mm glass sheets. Given the unusual (i.e. I've never seen before) nature of your problem, we might need quite a scientific approach to find the cause. Let me know if you would like to guidance on what test steps to take.
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Hanaldo
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Thanks Matt, by all means feel free to outline some tests for me to do; you know the material better than I do so I think the closer I can stick to what you are doing the better!
Unfortunately I don't have a whole lot of material left, but I'll do what I can with what I have.
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Hanaldo
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Ok, well I got round to doing a little 150x150mm test on a piece of glass, and it came out flawlessly:   Not one pinhole or void. So I think it is quite safe to rule out the material as a cause here, though I'm not totally sure where that leaves me... I would love to get that sort of perfection off a regular pattern, but I can't work out why it isn't working for me. Every actual mould I try to make comes away needing repairs, I just can't get a good result.
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Matt (Staff)
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+xOk, well I got round to doing a little 150x150mm test on a piece of glass, and it came out flawlessly: Not one pinhole or void. So I think it is quite safe to rule out the material as a cause here, though I'm not totally sure where that leaves me... I would love to get that sort of perfection off a regular pattern, but I can't work out why it isn't working for me. Every actual mould I try to make comes away needing repairs, I just can't get a good result. Hi Martin, It sure looks sunny where you are! Mmmmm, the photos of the flat sheet sample do look very good; a test like this is always helpful. I agree that this suggests there is no problem with the material. I wonder if there is an element of 'over-working' the prepreg in the more difficult areas. This is a phenomenon that can occur with the critical surface ply on a component layup too; if the surface is put-down, lifted, put-down, moved,.. etc.; it can cause minor problems along similar lines to what you're experiencing with the tooling system. This is difficult advice to give because we're trying to tread a line between making sure the material is well-and-truly down into all the details of the mould and yet at the same time not overworking it (which in the case of the XT135 surface ply can mechanically force the gel surface into and through the scrim. If this rings any bells though and you think to yourself "maybe I could be over-working it" then it might be worth a small test on a compound mould where you actually try to be a but less conscientious; of course you've still got to get the material into the corners but with an awareness to not overwork it. Generally speaking, we're still getting good feedback and seeing good finish on moulds produced by less experienced and less conscientious laminators than yourself which makes me wonder if you're actually trying too hard with it? [EDIT] Just looking again at your very first post I can see that the problem areas are not in the difficult corners (where would all have expected them to be). Is there anything you're doing in the lamination on those flat areas that could be different? - You've now made flat sheets with the material and they were good and you've got most areas of your complex mould are good, but the flat areas (which we've proved can work) are showing the problem.
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cumberdale
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Hi all, I've done my 50th XT135 mould this week. It feel like a new batch of surface and backing ply improved my results a little. I also made out a temperature sweetspot for the XT135 that is below room temperature, too warm and it can be such a pain to work with the surface ply. I feel like things might've also improved with Matt's recommendation to not use too much force on the surface ply. I'll do further testing this week to verify that on average (between batches) things indeed really have improved. To solve my issues with XT135, I've bought an additional vacuum pump and a digital pressure gauge, new connections, hoses ... just for the sake of absolutely knowing 100% that there is nothing wrong on that side of things. I still have a loss of 1mbar per minute in my vacuum line, and I can't seem to find that mini leak; this should not be an issue though as I leave the pump running either way. That mini-leak though got me looking into high-end vacuum connections as it literally drives me crazy that I can't find that leak. I've watched the XT135 instruction video for a gazillionth time and I just cannot figure out what's being done differently. I know that I am still relatively new to the game, and it still might be silly mistakes I am doing. But by now, working with XT135 has even gotten me to question the way I brew my coffee in the morning.  In all seriousness though, by now I've thoroughly revisited and redone my entire chain of steps and I try to be as smart as possible about it, but for now it certainly remains a tough nut to crack. If things don't improve this week, I will do tests similar to yours, Hanaldo. Could you elaborate on how you did your tests, e.g. force used on the ply, a single piece or multiple pieces, amount of layers, breather placement, ...
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Hanaldo
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Thanks guys,
I'm again quite confident that overworking the material isn't the problem, as this is something I'm very familiar with from when I first started using pre-preg. I know I did used to constantly reposition and slide and poke and move the pre-preg around, but that's something I'm very careful to avoid these days. Those flatter areas on my mould I barely worked at all other than just a firm pressure with the palm of my hand to warm the material slightly and get it to stick to the pattern surface. The trickier areas I used a dibber, and I was quite forceful there but as you said Matt, there's no pinholing in those areas. Then once the entire surface ply was down, I just placed the perf release film on and used a piece of breather with some light pressure.
Cumberdale, the flat sheet was just a simple copy of the layup I've been attempting on my actual patterns, ie. One layer single piece surface, 2 layers backing (one layer single piece, one layer was in 2 pieces) perforated release, breather over the whole lot. Only difference is I used flash breaker tape around the border to prevent excess resin bleed. Didn't really use any pressure on the surface ply, just enough to get it to take to the glass plate rather than my gloves!
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Matt (Staff)
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Guys, admire your desire to resolve this. Genuinely, if I thought it couldn't be resolved or knew in the back of my mind that the problems you were having were actually unavoidable or quite normal then I would come out and say it but the material can and should work. It is very sensitive, like just about any out-of-autoclave process, but under the right conditions it works great and is actually an extremely rare thing indeed (an out-of-autoclave tooling prepreg with a good surface finish). Cumberdale, I would certainly recommend a 'debugging' process like I suggested to Martin; strip it right back, ruling out as much as possible so that you start from a position of success and then introduce elements one by one until something goes wrong and then you'll know what it is. If you can't make a small flat square then there's no point in wasting time and material on a large complex mould but if you can prove you can make a small simple square then you have something to build on.
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Hanaldo
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Yeh I've seen enough to believe that it will work, so I'm determined to get it working. I mean after laying up a pre-preg mould, who wants to go back to wet-laying!?
Luckily I've found a local (local still meaning 5000km away - damn Australia!) supplier for an equivalent product to the S120, so I have been able to repair these moulds and bring them back to a good gloss. Though the high temp gelcoat I have is aluminum filled and my OCD just cant get over the thousands of silver specks against the black mould, so I still want to find the solution!
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SHaas
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Hey Hanaldo,
I am going to work with the tooling prepreg the next days. Did you solve your problem?
I also questioned in another postage abilities oft he S120 (or similar products) - I sprayed it on an Eg160 mould, used easy lease and made a prepreg component - but nearly all of the S120 was on the prepregs surface!
Matthieu has the idea that the sealer will not work at higher temperatures, but I think this could not be because in this case you could not repair Moulds with it...
So here is my next question: did you already repair prepreg Moulds with sanding and sealer? I see the problem coming that the mould I am going to make will have some imperfections because of a few pinholes in the part I want to make the mould of!?
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Hanaldo
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Yeh, I never managed to make a pinhole free mould with the XT135. Still believe it can be done, just ran out of material and havent had a need to get more yet.
As for the S120 - this is a great product. I havent actually used the S120 specifically, but I have used heavy duty mould sealers that do the same thing. It isnt quite as easy to use as you might first expect, but once you get the hang of it it is a really good product.
I did see your post about the S120 coming off your mould. This will have nothing to do with the temperature, these products will handle significantly higher heat than pre-pregs will expose them to - the one I use can handle 500°C, and I imagine the S120 will be similar. So I believe there must have been another issue, whether your prep prior to applying the S120 wasnt quite enough or whether there was a release failure, I think it will be somewhere more along those lines.
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