RTM 6 RESIN SYSTEM

[JeniaL]

Hello,

we got some parts that we have to produce by RTM using RTM 6 resin. previously have never worked with such resin system.
this is injection/cure cycle:
1. preheat resin to 80°C
2. preheat tool to 120°C
3. start injection
4. raise temperature to 180°C
5. dwell
6. cooling
my concern is about tool heating system. can't find any god source for a tool design. the part is pretty complex.

any help will be greatly appreciated.

 

[berkshire]

You are using a resin that is pretty thick and stiff to begin with and that has a very short cure cycle once you get it above 180*
you should be concerned about keeping the tool and the resin just under 120 * until you have completed the resin transfer/ shot
then, only then ramping up to 180* .
A lot of these tools use hot water passages in the walls of the tooling, others use electrical heating , here is a link to such a tool in Composites Magazine.
B.E.


You are judged not by what you know, but by what you can do.

 

[JeniaL]

thanks for the website. seems i'm getting into some interesting design or in other words PITA. hope Hexcel will give me some good alternate cure cycle.

 

[Compositepro]

Why do you feel you need an alternate cure cycle? Tool design is unique to each part design. Most tools are heated by putting them in an oven.

 

[JeniaL]

i already have aluminum tools that we used for prototypes (different resin system). tool was designed without any constant wall thickness. just a huge piece of aluminum. definitely at 180°C thermal expansion will work not in the way i want. to redesign the tools will take a lot of time and money. it's a crazy shaped closed mold. 5 Axis machining will cost us thousands of dollars. Airbus will not let me to change resin system (critical part). will see what Hexcel can advise me. currently there is one alternate cure cycle. ramping up to 160°C, dwell for 75 minutes and then free state post cure at 180°C.

 

[Compositepro]

Wall thickness and tool mass limit temperature ramp rates rather than temperatures themselves. If you don't want to heat your tool above 160C, then using a post cure should work fine. However, since you are dealing with Airbus, they may have a qualified curing process and will not allow deviations. It is up to them.

 

[JeniaL]

Airbus is ok with any manufacturer (Hexcel) cure cycle. any deviation is possible if i can prove that part is ok..that is what i'm going to do prior to submitting to them cure cycle details. this is the only resin system that qualified by Airbus for critical parts.

 

[JeniaL]

Got the response from Hexcel. Resin shall be cured at least at 160°C. Curing at low temperature just not possible. Injection Temperature may be reduced to 50°C