Flow / cure temperature

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Flow / cure temperature

Author	Message
Carbonphoenix	Carbonphoenix posted 7 Years Ago Topic Details
Group: Forum Members Posts: 12, Visits: 134	Hey guys I have started testing some bits using your prepreg and under a -1bar vac bag, I then put this into the oven and have tried both 100 and 110c for around 8hrs. When I come to remove the part, it feels like it has cured, but is very dry to feel. So I am a little concerned that my oven is going from ambient temperature to the 100 too quickly, and there is not enough dwell time at the flow stage (hope that's right terminology) Therefore, I am trying to find what is the flow temperature for your surface and backing prepreg layers, so I can look to programme my PID to dwell for longer at that temp before moving into the cure. Any ramp, dwell times and temperature ideas are very much appreciated, otherwise I will just sell carbon cheese graters. Kind regards Dave
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Hanaldo	Hanaldo posted 7 Years Ago Post Details
Group: Forum Members Posts: 2.5K, Visits: 28K	50 degrees for 1 hour, 60 degrees for 1 hour, 70 degrees for 1 hour. Then go to your final cure temp for 8 hours. Ramp no quicker than 1 degree per minute.
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Warren (Staff)	Warren (Staff) posted 7 Years Ago Post Details
Group: Administrators Posts: 2.5K, Visits: 7.9K	70C is the temperature where the resin begins to flow. If you skip through this stage too quickly then the resin won't have enough time to flow meaning you can get issues with pin holes. A dwell at 70C for a minimum of an hour is recommended when you are looking at higher temperature curing. As hanaldo suggests, 1C a minute is about right and that depends on size of the mould, how good your oven is etc. You may find for larger pieces you need to slow it down to allow the mould to catch up where as smaller moulds will heat up quickly. As such you may need to vary your cure cycle a bit to get perfect results. If you have time, generally longer and lower temperatures are better as issues like mould size, oven heating rate etc don't tend to be so much of an issue as the resin is curing at the optimum flow temperature anyway. A lot of people will tend to cure at 70 or 80 degrees throughout but you do really want a good 10 hours to be sure its fully cured. Warren Penalver Easy Composites / Carbon Mods - Technical Support Assistant
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Carbonphoenix	Carbonphoenix posted 7 Years Ago HOT Post Details
Group: Forum Members Posts: 12, Visits: 134	Excellent, thanks guys, I think that will give me enough to work with. I just need to get my head around my PID (omega cn7800) to program this correctly
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Hanaldo	Hanaldo posted 7 Years Ago HOT Post Details
Group: Forum Members Posts: 2.5K, Visits: 28K	Same PID I'm using. It works really really well once you get it figured out. Just a little tip when setting up the program, make your first temperature stage something like 35 degrees for 2 minutes, then program in the rest of the stages. For some reason with this PID, it ignores the ramp rate for the first temperature stage. So you could tell it to ramp up to 100 over an hour and a half, but it will just ramp straight up there in 2 minutes and then spend the rest of the ramp time hovering around that temp. But if you tell it to go to 35 and then ramp up to 100, it will ramp really nicely.
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Carbonphoenix	Carbonphoenix posted 7 Years Ago HOT Post Details
Group: Forum Members Posts: 12, Visits: 134	Thanks Hanaldo, I will take your advice. Pleased the PID is a good one, just understanding how to program it in layman's terms is proving a learning curve too lol
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Hanaldo	Hanaldo posted 7 Years Ago Post Details
Group: Forum Members Posts: 2.5K, Visits: 28K	Yeh I know, I thought the same thing when I first started playing around with it. Omega's instructions are horrible. Once you understand though, the PID itself is very simple to use. At least the functions that you need for pre-preg are anyway, I am glad I haven't had to try to figure out how to program dual loop control or hysteresis or any of that nonsense!
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