Durable Low CTE Composite Molds
Integran can electroplate a low thermal expansion (CTE) "nano invar" (aka Nanovar) variant of it's hard Nanovate metals to enable lightweight, low thermal mass, and durable carbon composite tooling. The invar plating process is stable and being run on a large scale (5x5'). Integran is now looking for industrial partners to help scale up this technology and finalize the "product" aspect of the commercialization. As with our other technologies, we are open to enabling partners through technology licensing.
Major advantages of Nanovate Composite Tools:
- Highly durable facesheet
- The Nanovate NV (nano-invar) is around 4x harder than invar and 10x harder than the composites it protects. Despite this hardness, it is very ductile and tough, making it resistant to scratching and impact damage.
- Vacuum integrity provided by metal Nanovate skin
- The Nanovate is fully vacuum integral given the nanocrystalline structure. While we can work with autoclave composites, out of autoclave (OOA) composites should be suitable as well.
- Low thermal mass for quick and lower energy cure cycles
- The thin (~200 micron) thick Nanovate surface cladding retains the low thermal mass that is so attractive with carbon composite tooling.
So how do we make these composite molds/tools?
We often get asked if we can apply our Nanovate materials to the surface of finished carbon composite tools. While we apply our materials over plenty of carbon fiber parts for durability, our experience shows that there a number of limitations for tools, including:
a) Thickness variations with geometry would be unacceptable for typically tightly toleranced tools (which is typical of an electroplating process)
b) While getting good adhesion to carbon composites is acheivable with our processes, it is difficult keep great adhesion at high cure temperatures typically seen in cure cycles and
c) The surface is difficult to get smooth - minor defects like nodules and roughness are impossible to avoid when building up a 0.008" thick skin. Because of the extreme hardness of Nanovate, it is a very time consuming process to get rid of these cosmetic defects.
For this reason, we decided to focus on coating the master model, similar to what you would do with a gel coat. The main difference is that the Nanovate NV coating is near a tool steel for hardness. Here is the process in more detail:
1) Machine a standard epoxy bead tooling block
2) Electroplate Nanovate NV to the surface
3) Lay-up and Cure Carbon Composite Facesheet
As discussed, this can be an autoclave or out of autoclave composite as the vacuum integrity of the composite facesheet is irrelevant. That is, the vacuum integrity comes from the nanocrystalline Nanovate metal. Voids and porosity (and eventually microcracks) in the composite are fine! Really!
4) Apply Egg-crate Backing Structure, remove Master Model and Postcure
There you have it. A low CTE carbon composite lay-up mold/tool with a near tool steel surface!
What was that tool in the example above?
This example is a 5x5' (1.5x1.5m) A320 Filet Fairing. You can see the part if you look closely at the panel behind the engine in this picture:
Why not get in touch!
Are you interested in Durable Composite tools? If so, please get in touch with us to discuss how we can work together!