Talk Composites - The Forum for Advanced Composites

Pre-Pregs not curing

http://www.talkcomposites.com/Topic27281.aspx

By Clemm - 6/18/2018 5:36:51 PM

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!
By nreindel - 9/10/2018 10:31:18 PM

 
Fasta - 6/19/2018 2:10:48 AM
Could just be your aluminium mould is sucking up much of the heat so assuming you are just measuring the air temp and timing from this your part is under cooked as it takes 45min to heat a mould like that.

I usually put my oven controller thermocouple in the air and just set my cure time to be 1 hour more than the cure time stated. You can't overcook it but you can under cook it. 

How did you come up with 45 min. extra cure time for OP's mold size? Is there a good rule of thumb to calculate cook time to add by mold mass/volume?