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K.C.C
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+x+xCan somebody tell me if this is correct. I see the xt135 prepreg tooling prepreg uses 1 layer of 250G and 2 layers of 415G adding up to 1080G m² So when I now handlaminate 6 layers of 200G twill 2X2 this wil give me 1200G m² Its for a split mould tube and I want the Tube to keep its form after postcure. What is the question exactly? Is 6 layers of 200g carbon enough for a mould? If it is small, then probably yes. A tube should be quite rigid by default because of it's geometry, so 6 layers should be fine. ok thnx
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K.C.C
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Full glass mould vs full carbon mould the moulds were bolted against each other and when come out of oven after post cure they stil were looking perfect , unbolted them and they warped They stayed in the oven over night after the post cure so didn't got them out whil worm.   
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Lester Populaire
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That is probably because of the shrinking of the big resin accumulation in the inside corners where the flanges start. As there is are no fibres there it won't make a difference whether you use carbon or glass...
I assume the gap is closing once you bolt them together?
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K.C.C
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Group: Forum Members
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+xThat is probably because of the shrinking of the big resin accumulation in the inside corners where the flanges start. As there is are no fibres there it won't make a difference whether you use carbon or glass... I assume the gap is closing once you bolt them together? The shrinking is more on the edges on the part itself and some on the flanges. I need to pull each side "open" to get the bolts in there. Yes I can stil bolt them together with force so it would be possible to make the parts. Maybee its the postcure cycle I use my max temp is 125°C I now bolthed them back together and put them in the kitchen oven for 2H at 135°C . My cure cycles is 20° 1H ramp 1°/min to 30° hold 1H and so on until 125°C and let cool over night With othe rparts that got more structures in them I dont got the warping . same cure cycle etc verry little gap when hold them together 
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Lester Populaire
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Group: Forum Members
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+x+xThat is probably because of the shrinking of the big resin accumulation in the inside corners where the flanges start. As there is are no fibres there it won't make a difference whether you use carbon or glass... I assume the gap is closing once you bolt them together? The shrinking is more on the edges on the part itself and some on the flanges. I need to pull each side "open" to get the bolts in there. Yes I can stil bolt them together with force so it would be possible to make the parts. Maybee its the postcure cycle I use my max temp is 125°C I now bolthed them back together and put them in the kitchen oven for 2H at 135°C . My cure cycles is 20° 1H ramp 1°/min to 30° hold 1H and so on until 125°C and let cool over night With othe rparts that got more structures in them I dont got the warping . same cure cycle etc verry little gap when hold them together My post cure cycle (different resin system tho) is a lot slower with 0.3°C/min and then a 10h at temp, and then again slow-ish ramp down.
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K.C.C
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Group: Forum Members
Posts: 54,
Visits: 117
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+x+x+xThat is probably because of the shrinking of the big resin accumulation in the inside corners where the flanges start. As there is are no fibres there it won't make a difference whether you use carbon or glass... I assume the gap is closing once you bolt them together? The shrinking is more on the edges on the part itself and some on the flanges. I need to pull each side "open" to get the bolts in there. Yes I can stil bolt them together with force so it would be possible to make the parts. Maybee its the postcure cycle I use my max temp is 125°C I now bolthed them back together and put them in the kitchen oven for 2H at 135°C . My cure cycles is 20° 1H ramp 1°/min to 30° hold 1H and so on until 125°C and let cool over night With othe rparts that got more structures in them I dont got the warping . same cure cycle etc verry little gap when hold them together My post cure cycle (different resin system tho) is a lot slower with 0.3°C/min and then a 10h at temp, and then again slow-ish ramp down. This is what was on the datasheet. The recommended post-cure cycle (above) calls for a temperature ramp from 50°C to 135°C. If a temperature controller with programmable ramp rate is not available then the oven temperature can be increased by 12°C every 2hours until 135°C is reached. Problem was that my heater in the oven is build for only 80°C and I boosted it out thil I could get to 125°C and the ramp takes really long the higher the temp is going. Wil need to add heat elements i nthe oven . But would this warping be caused by cure or resin build up ?
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Lester Populaire
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Group: Forum Members
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+x+x+x+xThat is probably because of the shrinking of the big resin accumulation in the inside corners where the flanges start. As there is are no fibres there it won't make a difference whether you use carbon or glass... I assume the gap is closing once you bolt them together? The shrinking is more on the edges on the part itself and some on the flanges. I need to pull each side "open" to get the bolts in there. Yes I can stil bolt them together with force so it would be possible to make the parts. Maybee its the postcure cycle I use my max temp is 125°C I now bolthed them back together and put them in the kitchen oven for 2H at 135°C . My cure cycles is 20° 1H ramp 1°/min to 30° hold 1H and so on until 125°C and let cool over night With othe rparts that got more structures in them I dont got the warping . same cure cycle etc verry little gap when hold them together My post cure cycle (different resin system tho) is a lot slower with 0.3°C/min and then a 10h at temp, and then again slow-ish ramp down. This is what was on the datasheet. The recommended post-cure cycle (above) calls for a temperature ramp from 50°C to 135°C. If a temperature controller with programmable ramp rate is not available then the oven temperature can be increased by 12°C every 2hours until 135°C is reached. Problem was that my heater in the oven is build for only 80°C and I boosted it out thil I could get to 125°C and the ramp takes really long the higher the temp is going. Wil need to add heat elements i nthe oven . But would this warping be caused by cure or resin build up ? My gut feeling sais it is a little bit of both but it is hard to say and there are other people on here who have more experience with split moulds.
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Hanaldo
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Yeh I'm gonna say it's a combination of both as Lester suggested. Really I feel the actual issue is the ramp rate was too fast and you don't have a fine enough control over the oven temperature (I've experienced warping when the actual temperature varies from the target temperature as little as 2 degrees C), which leads to stresses that cause the warping. Then you've got the resin build up in the corners which creates a big differential in temperature throughout the part, exasperating the stresses from the cure cycle.
It makes sense that you haven't experienced warping in more complex tools, as the geometry can overcome the stresses that are trying to distort it. This is why the flatter your components are, the more important it is to balance the layup and have good control of the cure cycle. It can actually be quite difficult to make thin pre-preg sheets without getting distortion because of that lack of balance in the layup, while if there was even a slight bend in the panel then it becomes significantly more rigid.
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K.C.C
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+xYeh I'm gonna say it's a combination of both as Lester suggested. Really I feel the actual issue is the ramp rate was too fast and you don't have a fine enough control over the oven temperature (I've experienced warping when the actual temperature varies from the target temperature as little as 2 degrees C), which leads to stresses that cause the warping. Then you've got the resin build up in the corners which creates a big differential in temperature throughout the part, exasperating the stresses from the cure cycle. It makes sense that you haven't experienced warping in more complex tools, as the geometry can overcome the stresses that are trying to distort it. This is why the flatter your components are, the more important it is to balance the layup and have good control of the cure cycle. It can actually be quite difficult to make thin pre-preg sheets without getting distortion because of that lack of balance in the layup, while if there was even a slight bend in the panel then it becomes significantly more rigid. The resin build up is the least problem because the part actually warped the most on the high spots   ordered new oven cotroller and added more heater elements in the oven to get better controle. Third time good time I hope.
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Hanaldo
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Yes, because the low corners have pulled inwards, which will push those high corners outwards.
In any case though, I don't feel the resin build up is THE problem, it just hasn't helped. The oven control is the problem, so I expect you will have better results with your upgrades. Be aware that this sort of issue is quite common with high temperature split moulds, and I would recommend slowing that cure cycle wayyy down below the recommended cure cycle. What Lester suggested isn't unreasonable, I tend to ramp at 0.5 degrees C per minute, but 0.3 isn't a bad idea. And I also do an extended soak at final cure temperature, sometimes as long as 24 hours at final temp. If you have the time, use it - there are no downsides to going slower with a free-standing post-cure other than having to be patient.
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