Hey guys,

Is anyone else using XT135 yet? How have your results been and what materials are you using for your patterns? 

I have been trying to make some moulds recently, and have used a bit more than 1m of the surface and 2m of the backing ply just making relatively smallish moulds (8 different moulds in total), but I haven't managed a single decent result yet. Every one of them comes out with pinholes, not all over the mould but enough to render them unusable. 

I am sure of my seal and I am sure of my oven and temp stability, so the one thing that I am unsure about is that I'm not using the XT135 with epoxy tooling board as being in Australia I don't have access to the S120 board sealer. So I have been making my patterns longhand by creating an initial plug in the conventional method of PU foam etc, then making a vinyl ester splash mould, and finally using that mould to infuse a new epoxy pattern. The epoxy patterns are great surface wise and cured up to 90 degrees for 24 hours, so shouldnt be any concerns there. Any Easy Composites staff reading this, are you aware of anyone else using the XT135 in this fashion? Can you see any reason this would cause issues? 


Does anyone have a solution for repairing these moulds to salvage them? The user guide states that they can be filled with a high temp epoxy gelcoat and sanded flat, but then the surface can't be polished up again and the S120 is needed again to bring the gloss back - obviously not an option for me. Has anyone tried flatting and polishing the surface of XT135, is it worth an attempt or no? Anyone have any other viable ideas for smoothly filling these pinholes? 

Will post pictures when I get a chance.

Hey Hanaldo,

As you may know already, I am using Easy Composites Epoxy Tooling Board + S120 Board Sealer in combination with XT135 for a few months now. Albeit I am happy with the three newest sealed moulds I have, the S120 definitely took time getting used to. And although I don't know too much about other mould-techniques, I don't think your problems stem from not using S120.
Being somewhat happy with the S120 nowadays, I shifted my focus to XT135, and I too have worked through 2m backing and 1m surface. My results sound similar to yours. I use moulds that are hardly larger than tennis-ball-size, so I can comfortably fit three moulds in a single vacuum bag. Although I have grown very confident in my vacuum-technique, I always leave the vacuum pump running during the cure cylce, just to be on the safe side. Also, by putting three moulds in the same vacuum bag, I can rule out leaks as a cause for the relative quality differences between the XT135 moulds. I am also very careful when pulling vacuum to eliminate all possible bridging spots. Primarily I have problems with tiny pinholes but at times I also have hefty 1mm diameter chunks of black epoxy missing independently of the location in the mould, revealing the glass scrim of the surface ply.

I have not been able to establish a direct causality between the quality of the XT135 mould with varying layup techniques, i.e. varying positioning of breather cloth, varying amounts of backing layers, varying debulk time and so forth. It still feels very random to me. In fact, from the thirty-something XT135 moulds I made, the one that bests them all in shininess, pinhole-freeness and general visual and haptic quality is an accidental XT135 mould, that, due to an error in my PID programming, went through a XC110 cure-cycle which should have been way way too hot and way too short. Of course the S120 did not take the heat very well, and I could not use that epoxy mould again. But this sort of makes the cure cycle my no. 1 suspect, but I am not ready yet to alter cure cycles. Before doing that, I thought of designing a very free-flowing/basic geometry (cnc mill, S120, layup ... everything done the same way) just for the sake to rule out that my 'original geometry' is not to blame for the issues I am having with the XT135 system.

I am looking forward to your pictures and I would love to hear more comments on this.

Sounds very much like the same issue. I'll get some pictures this afternoon.

Interesting that a different cure cycle seemed to help things. I've played around a little bit with that but not much, mostly just things like doing a warm debulk on the surface ply (30 degrees for 2 hours), and slowing down the ramp rate or having a short dwell at 50 degrees for an hour etc. None of these seemed to make much difference from the normal procedure so I have mostly just stuck to following the guide.

Im sure that the issue isn't that I'm NOT using S120, it's just that because I don't have access to the same materials as EC use in their video and their guide, it makes it tricky to troubleshoot. Like it may not be due to the S120 specifically, but is it potentially a problem that the guide has been written for the material to be used with epoxy tooling block and I'm using it with an epoxy laminate which has less mass and so would heat at a different rate, effecting the way the material behaves under the same cure cycle? It's just one of those things where I'm doing something different and getting different results, so it is hard to ignore. But the fact it sounds like you are getting similar results to me but using the 'correct' materials does make me hopeful...

Hi Guys,

Firstly, just to make sure but much of what I'll be reviewing here is included in the detailed processing guide for the XT135 system. I assume you've both read it but if not then you definitely should: XPREG XT135 Out of Autoclave Tooling Prepreg

Looking over your posts it's not an easy problem to diagnose in either case but I can certainly provide a little more information which might help to find the problem. In both of your cases, I don't think that the pattern (either the material it's made from or the way that it's finished) is the problem. The important thing with the pattern is simply to ensure:

1. Made from a compatible material (ideally epoxy)
2. Can take the 65'C initial cure temperature
3. Non-porous (which is where the S120 comes in but it not essential, depending on the material used.)
4. Prepared with a suitable release agent (again, that can take the 65'C initial cure).
5. Under no circumstances use polyurethane board or polyurethane primers/finishes.
6. Avoid vinylester (such as Uni-Mould) because compatibility of XT135 with vinylester is - as yet - untested.

I think in both of your cases you're using patterns that meet these criteria. - if not, start there.

So, having (probably) ruled out your patterns you're left with the following possible causes:

1. Laminating technique
2. Bagging technique
3. Cure cycle
4. Material condition

Of the above, #1 is the most likely cause of big pin holes and #4 is probably the most likely cause of tiny pin holes.

Laminating Technique
Laying up a prepreg mould is very different to laying up a component. You really need to be making extensive use of cut lines, joins and smaller panels of material that can move around slightly, relative to each other. If this is done correctly, it should very unlikely that you'll get a large cavity or void.

Bagging Technique
Much the same as the components themselves, making a void-free mould with high quality edges and corners would need good bagging technique. Martin (Hanaldo) you'll have covered this on the course and this is basically what we're talking about here - really ensuring the bag is down tight into every corner.

Cure Cycle
In the case of the XT135 tooling system, this part should be REALLY straightforward which is why I've not listed it as a likely cause of your problems. The *initial* cure of XT135 is simply a slow, low cure at 65'C. After that cure you'll be removing it from the pattern and the bag before its post-cure. At this stage, you can see the surface finish.  Because there's no ramp or dwell or other complexity, I would be very surprised if the cure temp is the problem.

Material Condition
The XT135 surface ply is much more sensitive to out-life issues than the backing. The reason for this is the glass scrim which performs best when it is only partially impregnated with resin. At room temperature the resin becomes more liquid and will start to wet out the glass scrim (we call this 'wicking'). This means that the material works at its very best when it is at its most fresh (with the least accumulated time out of the freezer. Although from a resin perspective there is still plenty of 'life' left in the resin (even after 4 weeks +) the wicking effect, particularly in warmer environments, does mean that this is one system that will perform better the fresher it is.

I know - as suppliers of the system - that we're not exactly impartial in this but I can honestly say that in general we're getting a lot of positive feedback on this product and that it continues to surprise us with just what we can do with it. As an example, you may have seen some photos on our Facebook and Instagram of the carbon fibre frame that a local composites wizz/bike builder is making. We've supplied him with materials in exchange for documenting his project but we've not done the work or really provided any more input than we would with any customer. He's now made all of the moulds for the frame (there's more than 10 individual moulds needed) and they have incredibly complicated and difficult geometry and accuracy required. They've all been made using XPREG XT135 tooling prepreg and the surface finish is completely flawless on every mould.

Please both have a think about some of the above points and see if anything sheds any more light on possible causes for the problems. I would be very happy to thrash this out some more until we have you both making perfect moulds too!

All the best, Matt

Matt Statham
Easy Composites / Carbon Mods - Technical Sales

Thanks for the reply Matt!

I'm glad you don't think the pattern material is a problem, I couldn't see how it would be either but it's just one of those things.

Laminating and bagging technique are potential issues, though as you know I do have good experience working with pre-pregs so I'm quite confident. I think I do need to come back and complete another course though, I hate feeling like my knowledge is past it's use-by (although to be fair, I've been itching for an excuse!). I did however laminate most of these moulds sort of as I would a component. I'll post some pictures this evening to help this make sense, but I did use some fairly large pieces on the larger moulds, as these are fairly simply shapes. The complex areas I did do lots of small pieces, ensuring any tight corners had material butted into the corners first before lapping with several other pieces. Similar story for the flanges. I made extremely sure that there was no bridging in these areas, and there were no creases anywhere either. I can't really see how doing the larger sections with smaller pieces of material would help as there really wouldn't need to be much relative movement there, but take a look at my pictures and feel free to tell me otherwise!

Again, bagging I'm confident with. The first 4 or 5 moulds I made, I paid really close attention. I did rush the last couple that I made, but surprisingly these were actually the moulds with the best results! There were some small voids in the tighter features as I would have expected with a small amount of bridging, but really nothing that worries me at all. These two moulds only had a couple of small voids exposing the scrim on the main surface, although there are still quite a lot of very tiny pinholes as well. I'm not too worried about those tiny pinholes really, I think by the time I've applied my semi-perm system there won't be too much issue. I'm more concerned about the voids that expose the scrim, as not only will these effect the surface finish but I'm also worried about release issues from mechanical locks etc etc. 

Cure cycle and out-life should be non-issues. I've really stuck to the guidelines with the cure cycle, and the material was only a week or so old when it was cured so shouldn't be a problem. Do you have any thoughts regarding doing a warm debulk? I can't really say I've noticed any difference, but I have been debulking at 30 degrees for a couple of hours just because it is fairly cold here at the moment (around 15-20C anyway... That's freezing temp in Aus!), so it just helps prevent the surface ply from lifting. Though if you think that may cause issues with the scrim 'wicking' and messing with the surface finish then that could be something I look at?

I am following the bicycle frame build with great interest! It is really what convinced me to purchase some of the XT135 and give it a go. I assume all of the moulds were produced from epoxy tooling board patterns?

+x

 

Hanaldo - 6/1/2018 4:00:20 AM

Thanks for the reply Matt!

I'm glad you don't think the pattern material is a problem, I couldn't see how it would be either but it's just one of those things.

Laminating and bagging technique are potential issues, though as you know I do have good experience working with pre-pregs so I'm quite confident. I think I do need to come back and complete another course though, I hate feeling like my knowledge is past it's use-by (although to be fair, I've been itching for an excuse!). I did however laminate most of these moulds sort of as I would a component. I'll post some pictures this evening to help this make sense, but I did use some fairly large pieces on the larger moulds, as these are fairly simply shapes. The complex areas I did do lots of small pieces, ensuring any tight corners had material butted into the corners first before lapping with several other pieces. Similar story for the flanges. I made extremely sure that there was no bridging in these areas, and there were no creases anywhere either. I can't really see how doing the larger sections with smaller pieces of material would help as there really wouldn't need to be much relative movement there, but take a look at my pictures and feel free to tell me otherwise!

Again, bagging I'm confident with. The first 4 or 5 moulds I made, I paid really close attention. I did rush the last couple that I made, but surprisingly these were actually the moulds with the best results! There were some small voids in the tighter features as I would have expected with a small amount of bridging, but really nothing that worries me at all. These two moulds only had a couple of small voids exposing the scrim on the main surface, although there are still quite a lot of very tiny pinholes as well. I'm not too worried about those tiny pinholes really, I think by the time I've applied my semi-perm system there won't be too much issue. I'm more concerned about the voids that expose the scrim, as not only will these effect the surface finish but I'm also worried about release issues from mechanical locks etc etc. 

Cure cycle and out-life should be non-issues. I've really stuck to the guidelines with the cure cycle, and the material was only a week or so old when it was cured so shouldn't be a problem. Do you have any thoughts regarding doing a warm debulk? I can't really say I've noticed any difference, but I have been debulking at 30 degrees for a couple of hours just because it is fairly cold here at the moment (around 15-20C anyway... That's freezing temp in Aus!), so it just helps prevent the surface ply from lifting. Though if you think that may cause issues with the scrim 'wicking' and messing with the surface finish then that could be something I look at?

I am following the bicycle frame build with great interest! It is really what convinced me to purchase some of the XT135 and give it a go. I assume all of the moulds were produced from epoxy tooling board patterns?

I can't really see how doing the larger sections with smaller pieces of material would help as there really wouldn't need to be much relative movement there, but take a look at my pictures and feel free to tell me otherwise!

I agree, the small sections are only necessary for the tighter, more intricate sections, not the flatter areas.

Though if you think that may cause issues with the scrim 'wicking' and messing with the surface finish then that could be something I look at?

Yes, this is worth looking at (especially because it seems we're running out of other explanations). The warmer it is, the more the wicking will happen. At 30 degrees I think you'll see this happen a lot. You should be fine getting the material to take to the mould at 20'C (normal temp for us).

Also, it's worth considering whether the XT135 could have been exposed to high temperatures on its trip over to you? - As you know we're subject to ambient temperatures on the flight over and I just wonder whether the material spent a few days in a very hot customs container or storage area on its way to you. If it was hot enough, this might be all it would take to take away the 'dry' breath-ability of that scrim layer.

I am following the bicycle frame build with great interest! It is really what convinced me to purchase some of the XT135 and give it a go.

Yes, it's an exciting project, in fact, the very first bike frame is in the oven at the moment on a debulk before the main cure today so we should see the first frame by the end of the day!

I assume all of the moulds were produced from epoxy tooling board patterns?

Yes, all machined from EB700 epoxy tooling board. 

Matt Statham
Easy Composites / Carbon Mods - Technical Sales

Ok, had some trouble getting photos uploaded, but here we go:

This is how I kitted up. The flanges I didn't kit for, just used strips of material as appropriate:



Surface ply down:




Debulk:










2 layers of backing ply down:




And the results:












Interestingly, all of the trouble is on the flatter surfaces, for the most part there are no pinholes on the radii as I would expect with a bit of bridging:






The most frustrating part is how close they are. They are so close to being perfect moulds, but the pinholes and the inability to repair them means they are just

Hey Hanaldo & Matt,

thanks for your replies!

I can confirm that these chunks of missing epoxy that reveal the glas scrim seem very familiar to the defects in the moulds I have made. However, due to the smaller size of my moulds I have had only a few of those larger voids in every other mould, so it is a bit difficult to compare to your mould. I experience these voids rather randomly, regardless of the corners, radii or flat areas. If your straight-forward geometry experiences similar issues, I don't think my the geometry itself is to blame for the defects. However, when I do have multiple voids they usually are in close proximity to each other, whereas the rest of the mould is otherwise fine with only a few dozen or so smaller pinholes across the entire mould. This too looks somewhat similar to your mould.

I haven't had the time to make new XT135 moulds yet, but my first change will be to make use of smaller panels of material as Matt suggested. But I find it super strange that such large voids are possible in a mould that is otherwise pretty decent. It is as if giant pockets of air get trapped under the surface ply, unable to be pulled by the vacuum pump.

As I do multiple XT135 moulds per vacuum bag, I am pretty sure the vacuum and the my bagging technique are not to blame. I sometimes get one XT135 mould that has maybe 30-50 tiny pinholes, but no glass-scrim revealed, whereas another XT135 from the same bag suffers from 2-3 larger voids, yet has fewer tiny pinholes, also in different locations than the first mould. Again; multiple XT135 moulds made in the same debulk bag, same layup, same vacuum bag, yet different results for each XT135 mould from that bag. Just very inconsistent.

Matt Statham
Easy Composites / Carbon Mods - Technical Sales

No 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.