clavecore lt process 4 25 2019 - acmtucson.com · 3uhsuhj od\xs wklfnqhvv § ; ilqdo odplqdwh...
TRANSCRIPT
ClaveCore LT Process
Advanced Ceramics Manufacturing
Grade Selection
• What is your target pressure?
• What is your maximum cure temperature?
• What is your Volume % (V%) expansion?
Volume ExpansionWork backwards from final geometry to get mandrel geometry. Consider a cylinder of unit length (L=1).
CompositeWall
Thickness
Expanded Mandrel Diameter
(Post Cure)
Final Dimensions
PrepregLayup
Thickness
Starting Mandrel Diameter
(Pre Cure)
Starting Layup
Dimensions
Volume ExpansionThe cure and lamination process causes consolidation (thickness reduction) of the prepreg that is assisted by the ClaveCore pressure. This change in thickness helps define the change in mandrel volume.
If you know your final laminate wall thickness, your prepreg debulking efficiency can be used to get your starting prepreg layup thickness.
If you do not know this value, a rough assumption we have used is:Prepreg layup thickness ≈ 2X final laminate thickness
Volume ExpansionCalculate your starting/initial mandrel volume and your final mandrel volume. Here is an example for a simple cylindrical geometry.
Vi=initial mandrel volume=Lπri2 (cylinder geometry)
Vf=final mandrel volume=Lπrf2
V% Expansion=(Vf-Vi)/Vi x 100
Consider a cylinder of unit length (L=1), starting diameter of 2 (ri=1), final diameter 2.25 (rf=1.125).V% Expansion=(1.1252-12)/12 x 100=26.6%
Volume ExpansionCalculate your starting/initial mandrel volume and your final mandrel volume. Here is an example for a simple cylindrical geometry.
Vi=initial mandrel volume=Lπri2 (cylinder geometry)
Vf=final mandrel volume=Lπrf2
V% Expansion=(Vf-Vi)/Vi x 100
Consider a cylinder of unit length (L=1), starting diameter of 2 (ri=1), final diameter 2.25 (rf=1.125).V% Expansion=(1.1252-12)/12 x 100=26.6%
ClaveCore grade depends on process conditions (namely, pressure required, cure temperature, and volumetric expansion of the mandrel
as the pre-preg compresses). Use the process parameters to see which grade gives target pressure
If using the Teflon tape sealer, consider targeting an additional 20-30psi over pressure to stretch the tape.
Peak Pressure [psi]
[0% Expansion] [5% Expansion] [30% Expansion]
Commercial Grade
120°C 180°C 120°C 180°C 120°C 180°C *Pressurization Model
LT-A 90 130 90 140 60 80 P(T,V%) = (-0.012*T+0.315) *V% +0.616*T+16.65
LT-B 160 230 160 230 80 110 P(T,V%) = (-0.027*T+0.959) *V% +1.186*T+20.05
LT-C 210 280 200 280 120 150 P(T,%V) = (-0.018*T-0.697) *V% +1.079*T+88.5
LT-D 230 270 220 270 140 200 P(T,V%) = (0.011*T-4.767) *V% +0.750*T+140.3
LT-E 250 370 240 340 170 220 P(T,V%) = (-0.027*T-0.058) *V% +1.504*T+76.21
LT-F 90 130 80 120 45 90 P(T,V%) = (0.005*T-2.104) *V% +0.623*T+15.61
LT-G 100 160 90 130 50 80 P(T,V%) = (-0.009*T-0.625) *V% +0.790*T+0.728
LT-H 140 180 110 160 80 100 P(T,V%) = (-0.009*T-0.835) *V% +0.821*T+26.94
LT-J 150 190 140 190 80 110 P(T,V%) = (-0.006*T-1.970) *V% +0.795*T+51.95
LT-K 100 230 90 200 70 130 P(T,V%) = (-0.032*T+2.613) *V% +1.645*T-92.90
LT-L 90 190 100 150 20 90 P(T,V%) = (-0.005*T-2.249) *V% +1.471*T-80.52
*Pressurization Model Notes: T=°C, V%=Volume Expansion (Enter 50% expansion as
“50.0”)
*Be sure your closed mold is designed to resist the pressure
expected*
Process for Creating a Water Soluble Tool/Mandrel/Core from ClaveCore LT
Line female mold with an offset material (e.g. wax, cured composite part) at a measured thickness
identical to the thickness of the pre-preg material to be used for the final part.
For example, if you use 5 layers of pre-preg and each layer is 0.010”, create an offset of 0.050” in the tool.
Utilize a release material if offset material doesn’t also act as a release. We
recommend Teflon tape.
Close the tool up and fill it with ClaveCore powder. Pressure will build up inside the tool as the ClaveCore heats and melts, so ensure there
are no voids for the material to escape out of.
Heat the tool to 85-95 Celsius (depending on ClaveCore grade used) and hold for a certain length of time
(depending on dimensions of tool used)
ClaveCore Commercial
Grade
Mandrel Forming Temperature [C]
LT-A 85LT-B 85LT-C 85LT-D 85LT-E 85LT-F 95LT-G 90LT-H 85LT-J 85LT-K 90LT-L 95
• Time starts once the mold has hit the target temperature
• If the mandrel is not fully formed:• Increase time by 30min increments• Increase temperature by 2C
increments• It is best to form the mandrel and the
lowest temperature possible to ensure the mandrel is thermally stable
Allow the tool to cool down to room temperature before removing the mandrel. Once removed, keep mandrel away
from moisture and heat.
• Store mandrels in bags with desiccant at <40F until ready to use
• Allow mandrels to warm in bag before use to prevent surface condensation
Using the ClaveCore mandrel to create your composite part
Wrap the mandrel in Teflon tape or your preferred material to prevent resin infiltration into the
mandrel during the curing cycle.
Be sure to remove the offset material from the tool.
Lay up your taped mandrel with pre-preg material and place back in tool.
Secure tool and run thermal curing cycle according to pre-preg’s specs.
E.g. 350 F for 2 hours
If possible, open valve on tool after cure cycle while still hot. Material will still be hot and pressurized so it will
self-eject through an open port while hot.
Allow the tool to cool down before removing the cured part
Trim the part to size with mandrel still inside, if desired
Wash out the mandrel with tap water and pull the Teflon tape out, leaving you with your finished part
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