SHD have a new material they are developing. Its a higher temperature cure but still classed as a low temp resin system with an 85 degree C cure being needed. The spec sheet recommended cure will be all you need to use (Currently it is 65 degrees for 2 hours with a 1 degree per minute ramp then 16 hours at 85 degrees C with the same ramp rate to get up to temp) and it works perfectly.  I have made two parts this week. One had some pinholes  (60 degree C, dwell 60 minutes, 70 degree C also 60 minute dwell then 85 degrees for 16 hours). The second was perfect with the cure I first mentioned (65 degrees for 2 hours then 85 for the rest of the cure). Speed of ramp is important but I think the dwell and staged cure is the key. If I know the gel time then I could ramp up after that to speed the cure up but then the energy needed to run those higher temps means all I am saving is time not energy. 


The above part has pinholes. Not big ones but I can see them. The clarity of the new resin makes it a pain to get photos of indoors so its like taking photos of a black mirror.

Below the part is flawless and it was a simple cure cycle change. Its hard to believe a small difference can make such a change but it shows how the use of a good controller can possibly improve your parts. 



To avoid cheating and posting images of prepped or finished parts all my photos are out of the mould and untrimmed. This is exactly how they come out of the mould good or bad. 

We have tested a few OOA carbon fiber prepregs some time ago, and generally OOA prepregs works with simple geometry.
Complicated geometry results in pinholes (often small - but to sell products to client you need to works with pinholes - time consuming painting)

Since we bought autoclave we have 0 pinholes problem. 

Carbon fiber sheets and composites .
www.dexcraft.com

It may not be the most complex shape but it does have compound curves and several changes of direction and tight corners to lay into. This was the first out of the new mould so I expected one or two issues but pinholes is not one of them. The SHD material really is an amazing OOA product..

Same with EasyPreg. I had some issues making these parts initially, but after working on my cure schedule (with some help from morepower!) and layup technique I can bang them out 100% pinhole free now. Top picture is straight out of the mould with just the outside edges trimmed, bottom picture is trimmed and clear coated (just for the sake of it, a lot of people think clear coating shows up pinholes that otherwise can't be seen. Nothing of the sort here!). It's definitely possible to get genuine free results with good quality OOA pre-preg.

Hanaldo, I think it is most want to have a material where the guidelines given work 100%, 100% of the time regardless of what oven they have or how they run the schedule. It does take some work and needs to be done correctly with a controller. Do that and work on the timings and ramp rates a little and it does work perfectly as you and I know.  If I could just say do A, B, C and D then it works that would be great. But you cannot allow for people doing it manually or the small lay up issues people 100% right with your lay up and bagging and then it is all down to the oven and the controller. I think a ramp and dwell controller is as important as any other part of the process.  

Ive been using shd a lot more at work. But the vtc401 in the clave and the press. Hopefully trying out df212 this week on some sports equipment.

The ones I get caught on are the complex tricky pieces, as the moulds tend to vary a bit in thickness. In some places they can be as much as 20 or 25mm thick, in others they are between 5 and 10. Simply the draw back of wet laid moulds and overlapping layers of CSM. These moulds take a bit of figuring out, and I've worked out they usually need a much much slower ramp and dwell cycle. I suppose you need to cater for the thickest part and it doesn't matter what the thinnest parts are. 

Another thing I worked out was specifically with the PID controller I'm using (an Omega CN7800). For whatever reason, the ramp setting don't work on this controller if you don't give it an initial dwell point. So I used to tell it to ramp up to 55 degrees over an hour, but it would heat straight up to 55 in like 2 minutes and then just hover around there for the hour duration. Initially I thought the ramp control just wasn't any good, but then I noticed that when it ramped up to the next stage of 75 degrees it would take the appropriate amount of time. So now I tell it to ramp up to 20 degrees over 2 minutes, hold that for 2 minutes, then ramp up to 55 over an hour. This works perfectly and helped greatly with the finish.