Dwell Times for VTF

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#1

Hi all,
If anyone out there is using VTF, what are your dwell, ramp and peak temp figures?

I have had good success with a straight forward 12 hour cure at 70C, no ramping:

However, I would like to knock parts out quicker. I have experimented with higher temps and different dwell times, but none have yielded results as the example above (either pinholes or print through happen). I have followed the 2 degrees/minute ramp rate and dwells at 65 as the spec sheet recommends.

Any tips appreciated,
Thanks

#2

I have not got any tips for you.

I was just curious, what’s VTF?

I use a Umeco VTM pre preg. Is that another Umeco product?

#3

I run at a 1 to 2 degree per minute ramp rate. Get to 65 degrees C and dwell for an hour. Then ramp up to 85 degrees for the remaining time and depending on the starting temp the total cure time is about 8 hours. No pin hole issues unless it is from my poor technique…lol…

How lond do you leave the parts in the bag before you cook them?

#4

Yes it is their Out of Autoclave Carbon. It is not cheap (really not cheap) compared to some but the results can be a perfect pin hole free surface with just an vac bag and oven cure. I have tried so OOA pre-pregs from SHD, PRF and Gazechim and none of them can match VTF261 for surface finish. It can look as good as parts used in F1 or Moto GP without the expense of an Autoclave. But the material is between 30-50% more then the other suppliers materials. But they know none of the other suppliers can match the quality.

#5

Are you building the breather stack the way they reccomend too? I always run peel ply round the edge of the flange but NOT on the part. I use the lightest weight breather too. The only change I have made is the relase film as I use a none perf…

#6

I want this stuff then, I’ll have to ask my supplier.

#7

I have managed to get good results now by increasing the temperature at 1C/min, not 2.
I use single glass tows under the surface of the VTF about 200mm apart, on the flange, making sure they touch the breather. Yea, I’m using light weight breather and non perforated too.

#8

Ok… I run a band of peel ply under the extended first VTF surface layer and cut the other layers a little shorter than the first surface layer… Have run up to 100degrees C when we needed to speed up the cure but always run a 60 minute 65degree dwell…