Why Autoclaves Are Still the #1 Prepreg Carbon Fiber Solution

If you are a manufacturer who regularly uses prepreg carbon fiber, you have some important decisions to make. Aerospace industries have proven the success of autoclaves. Yet, other sectors tout that out-of-autoclave (OOA) options are comparatively more cost-effective.


Gail Han, the Non-autoclave (Prepreg) Manufacturing Technology Program manager at Boeing Research & Technology (St. Louis, Mos.), has been quoted as saying: “Aside from the hype, is OOA a good tool? Yes, but is it a game changer for all applications in the industry? Not necessarily. 

How can you make the right choice for your industry and business? Consider common challenges to the industry:

Problem: Air Voids and Weight

Air voids and component weight are two challenges that can go hand-in-hand. For instance, if your component has more air voids, it will most likely require more paint to keep an attractive aesthetic. While this weight increase may seem minimal to the ‘Average-Joe,’ this can significantly impact industries that require ultra-lightweight carbon fiber components. It can affect a project’s effectiveness and, ultimately, your business.

Solution: Pressure

Many OOA alternatives carry a higher risk of air-voids and require more time and effort to develop foolproof curing methods. In contrast, carbon fiber autoclaves operate at high-pressure and can still guarantee a complete vacuum on the part. The pressure is vital for manufacturing polymeric composites because it consolidates the prepreg plies to form a solid, strong material. 


It makes sense: we all press things to stick them together. Even in everyday scenarios! For example, you press your hamburger so that it holds together while you eat it. Too much pressure and the condiments squeeze out. Too little pressure and the sandwich falls apart; the perfect pressure is essential! Prepreg carbon fiber autoclaves give you that delicate control. It will keep your resin in place while eliminating air voids. 

Problem: Gradual Heat Source

Heat is likewise crucial because it begins and ends the curing reaction for thermoset-based prepregs. 350-degree cure epoxy systems are more fluid than their 250-degree counterparts. They require more heat and pressure to squeeze everything together to eliminate voids. When this new epoxy was born, the prepreg autoclave got its beginnings in the aerospace industry.


Alternative methods, such as resin transfer molding (VARTM), resin infusion techniques, and resin transfer molding (RTM), lack the heat and pressure control necessary to get consistent laminate consolidation. Contrastingly, autoclaves were made for this! 

Solution: Precise Controls

The usual procedure for autoclaves involves vacuum first, pressure, and then heat. Within the process, the resin transforms from a liquid into a solid. The heat rise must be gradual. Otherwise, you will compromise the strength of the component. The finesse and programmability of carbon fiber autoclaves solve this complication. Didion Autoclave offers customizable controls with their products, ensuring that you’ll get the perfect cure every time.

Problem: Cost

Cost is undeniably another complication when it comes to autoclaving. While there is a greater up-front cost of purchasing a prepreg autoclave, you can find savings during its years of reliable service. OOA’s are known for having a longer curing time because of the “edge-breathing” strategy required to release trapped volatiles, including air and moisture—coupled with the air-extraction process necessary to keep the vacuum, the cost of time and hassle with using OOA methods increase. 

Solution: Lifetime Savings

In contrast, with the functionality of autoclaves, you can “set and forget.” Having this ability will maximize the resources you already have. Your employees can focus on additional projects while the current component is being correctly and efficiently cured. 


Carbon fiber autoclaves give your components consistency you can count on. Not only is this important to you, but it is also essential to your end-user. By having a reliable method for lamination, you will be able to give your customer quality guarantees, which will increase customer acquisition and satisfaction.

While OOA methods undeniably have their place on the market, autoclaves have a proven presence that cannot be ignored or disregarded. Contact us today for a free quote on a prepreg carbon fiber autoclave that fits your specifications and process.

Curing chart for prepreg carbon fiber autoclaves.