Why Autoclaves May Eventually Become a Thing of the Past

1. Why Autoclaves May Eventually Become a Thing of the Past It is entirely possible to create carbon fiber parts at home without applying high heat and pressure to your layup. But in a commercial setting in which quality is uncompromising and tolerances are slim, parts are cured in an autoclave under high heat and pressure. The question is this: will the autoclave ever become a thing of the past? It is possible, according to a research team at MIT. The team has developed a way to mimic what an autoclave does using carbon nanotubes and electricity. If they can manage to scale it up enough to make it commercially viable, they may bring about the end of the autoclave. Nothing would make aerospace manufacturers happier. The Autoclave Concept If we were to create carbon fiber auto body panels for a customer, we would start with a tool (mold) in the shape of the desired panels. Then we would apply multiple layers of carbon fiber fabric impregnated with an epoxy resin. The completed tool and layup would be put into an autoclave for curing. A company like Boeing would follow the same general principle for manufacturing airplane wings. There is one significant difference, though. We would need a relatively small autoclave to cure auto body panels. Boeing's autoclave, by comparison, would be monstrous. It would have to be the size of a small warehouse in order to accommodate the length of the wings. As you might imagine, it takes a lot of money to operate such a large autoclave. Boeing and its aerospace competitors spend a ton of money curing parts. If there was a way to accomplish the same thing while spending less, you bet they would be thrilled to have it. The secret of the autoclave is heat. Producing the necessary heat is a costly venture. Replace that heat with a comparatively small amount of electricity and you change the game completely. Parts cure faster, they require less space for curing, and the relative cost of the finished parts fall significantly. It is a winning situation all the way around. Curing with Electricity So, just how does this new curing technique work? It starts with manufacturing a thin film from carbon nanotubes. A carbon nanotube is a tube made of carbon molecules that is so small it can only be observed on the nanoscale. Carbon nanotubes are highly conductive, which leads to the next step.

2. MIT researchers discovered that they could wrap uncured carbon fiber parts in their carbon nanotube film and then apply electricity to the assembly. The electricity generates enough heat to bond the layers together and cure them. Best of all, the process uses only 1% of the energy required by the autoclave to do the same work. The process also eliminates the space requirements of your typical autoclave. You only need enough space to accommodate the very part being cured. That leaves more room for production. Scaling It Up Researchers have only worked on small samples to date. Now that they have proven their system works, it is time to begin scaling up to tackle larger parts in a more realistic setting. Their biggest challenge is coming up with cost-effective ways to manufacture larger sheets of carbon nanotube film. In the short term, the new process is likely to cost more than autoclave curing. But once scaling is complete and nanotube manufacturing is streamlined, costs should drop significantly. At that point, the aerospace industry will be on board. Everyone else will eventually follow. As for the autoclave, it will quietly fade away after serving its purpose for so many years.