Hello all,

              I am currently having a problem with my Xpreg XC110 prepreg. In my last test the prepreg did not cure and was still  gooey once the cure cycle was complete. My oven, which is home is set up with a proper PID controller complete with the thermo coupling. Its shows to have reached the temperatures that are recommended for the XC110 system. My mold is a CNC'ed piece of aluminum 2" thick. The mold itself is 20" x 46" x 2" With basically the back and sides of a guitar cnc'ed into it. When I did the trial run once it had soaked for an hour at the higher temp I lifted the oven off the mold so it could room cool. So, what would be my problem? 
A. I should have left the oven over the part to let it slow cool
B. the aluminum is taking to long to reach temperature
C. the oven isn't actually reaching the temperature the thermo coupling says it is. 
Any other ideas on what it may be would be of great help.

Also, unlike the video my surface finish is almost like dry carbon, there is no clear looking finish on it at all. Does the Paper side of the pre-preg go down first or the plastic side? or does it matter? and could it be the either over cooked or under cooked problem that could have also caused that?  Any help would be greatly appreciated. Thanks!

JC

A number of factors could play an impact here but a large aluminium tool seems the most obvious issue in that it will take a long time to heat up and cool down so although the oven air temperature may have followed the cure cycle, due to the extra energy needed to heat the aluminium tool, the tool is probably lagging behind temperature wise by anything up to an hour or maybe longer. Ideally you would want a thermocouple as close to the mould surface as possible so you can monitor how long it takes to actually get to temperature.

We would suggest that the paper side goes against the mould surface.  In cosmetic terms, the side against the backing paper, fractionally has more resin on it and is slightly more tacky. This means applying that side to the mould may help to slightly improve the cosmetic finish of the part.

If the part has not properly cured, then the surface finish is likely to be degraded hence the matt  finish and potentially even print through.  Demoulding before the part has cooled down can sometimes cause this effect too.


Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant