Manufacturers desire high strength and lightweight products. Elite companies take advantage of carbon fibers and their simple process.
Is it time to consider carbon fiber parts in your manufacturing?
The aerospace and medical industries are shifting parts to carbon fiber production. So, to learn more about the process and how it can work for your product, read on.
3 Parts of Carbon Fiber Production
The first part is the pre-preg process, which involves making carbon fiber sheets. Carbon fibers are woven into uniform strands. Then, heated together creating pre-impregnated sheets.
After that, fabrication is next. Raw material like epoxy resin forms a pre-fabricated composite. This includes mixing and applying unidirectional curing resins.
The product is ready once cured under high-temperature polymerization.
The final process is post-preg processing. Therefore, this requires more resin added to the pre-fabricated composite and cured.
The custom carbon fiber parts are light. They are strong enough to withstand live loads of 600 pounds per square inch without failure. Other benefits of using carbon fibers include:
- High tensile strength compared to weight ratio
- High fatigue strength
- A low thermal expansion rate
- Improved stiffness to weight ratio
Classification of Carbon Fibers
Tensile modulus measures how much pulling force a certain diameter fiber can exert without breaking. The unit for tensile modulus is psi. The strongest carbon fiber is about five times stronger than steel.
Graphite fibers are ultra-high modulus fibers made from petroleum. Therefore, these fibers have an internal structure like a three-dimensional crystal.
The plastics get molded into long strands. They are heated to a very high temperature without letting them touch oxygen. The fibers can’t burn without oxygen.
Instead, the high temperature causes the atoms in the fiber to shake. Therefore, most non-carbon atoms displace.
The Manufacturing Process
Carbon fiber parts get formed from polyacrylonitrile or rayon, and sometimes petroleum. They’re made from a proprietary mix of long strings of molecules that come from carbon atoms.
For example, here are the main stages of the process.
Fiber Spinning
- Acrylonitrile plastic mixes with another kind of plastic to make polyacrylonitrile. This occurs in a process called suspension or solution polymerization.
- The plastic transforms into fibers. Chemicals pump the fibers into a chemical bath to become solid fibers. Or, mixing plastic and heated chemicals until they evaporate.
- After washing and stretching, fibers become thinner. Molecules align, heat, and become strong.
Stabilization
- Making carbonized fibers requires chemical alterations. Fibers heat in the air to about 390-590° F (200-300° C) for 30-120 minutes. The fibers pick up oxygen from the air and their bonding pattern changes.
- The stabilization process may use a variety of techniques. In some cases, fibers draw through heated chambers. Or, the fibers pass over hot rollers and through materials held in suspension by hot air. Consequently, some use heated air mixed with chemicals to speed the stabilization.
Carbonization
- Then, stable fibers heat at 1,830-5,500° F. This is for several minutes in a furnace that does not have oxygen to the fibers from burning.
- Then, heated fibers lose atoms. This includes water vapor, ammonia, carbon monoxide, and carbon dioxide. As a result, the remaining atoms form tight, bonded carbon crystals. They align parallel to the long axis of the fiber.
Oxidation of Surface
- After carbonizing, the fibers’ surface oxidizes, preparing for better bonds.
- The oxidation requires immersing the fibers in the air, carbon dioxide, or ozone. On the other hand, other solutions include sodium hypochlorite and nitric acid. An electrolytic process coats the fibers.
Fiber Sizing
- After oxidation, fibers are coated for protection during weaving. The sizing materials work with the adhesive to form composite materials. For instance, coating materials include epoxy, polyester, nylon, and urethane.
- Wound on bobbins, fibers twist together to make yarn of different sizes.
Carbon Fiber Production Equipment
Few companies get into carbon fiber production or its equipment. To clarify, they prefer outsourcing their carbon fiber products to experienced companies like SMI Composites.
Above all, SMI Composites knows how to make high-quality carbon fiber parts. So, Give us a call today to learn how we can make your custom carbon fiber parts.
