Understanding carbon fiber reinforced thermoplastics(CFRTP)

Carbon fiber is a high performance fiber material, which is mostly fused with resin, metal, ceramic and other matrix materials in the actual use process, among which resin is the more commonly used matrix material. According to the different resin matrix, carbon fiber composites can be divided into thermosetting carbon fiber composites and carbon fiber reinforced thermoplastics.

What are the types of carbon fiber reinforced thermoplastics?

Carbon fiber reinforced thermoplastics(CFRTP) are composites with carbon fiber as the reinforcing material and thermoplastic resin as the matrix. From the reinforcement method of carbon fiber, it can be divided into long-cut carbon fiber (LCF) reinforced thermoplastic composites, short-cut carbon fiber (SCF) reinforced thermoplastic composites and continuous carbon fiber (CCF) reinforced thermoplastic composites.

Long-cut carbon fiber and short-cut carbon fiber mainly refer to the application length of carbon fiber materials, there is no strict fixed distinction between the two, generally between a few millimeters to a few centimeters, the more common specifications are 6mm, 12mm, 20mm, 30mm, 50mm. However, the mechanical properties of both short and long carbon fiber-reinforced thermoplastic composites are far inferior to those of continuous carbon fiber-reinforced thermoplastic composites. Therefore, MDC Moulds usually use continuous carbon fiber reinforced thermoplastic composites.

Carbon fiber reinforced thermoplastics can also be classified according to the thermoplastic resin. There are many common thermoplastic resins, such as PE, PP, PVC, etc. However, thermoplastic resin composites with carbon fiber reinforcement are mostly used in aerospace, precision equipment and other demanding working environments, so carbon fiber thermoplastic composites are more often made of polyether ether ketone (PEEK), PPS, polyimide (PI), polyetherimide (PAI) and other mid- to high-end thermoplastic resins are used as the matrix.

Advantages of Carbon Fiber Reinforced Thermoplastics

Carbon fiber-reinforced thermoplastics are suitable for making high-end machinery parts with excellent machinability, vacuum molding, stamping moldability and bending processability, and can be re-molded once the material reaches a certain temperature again. For example, MDC Mould has been able to add a recycling process to the process to shred and recycle carbon fiber-reinforced thermoplastic trim after compression molding, based on specific needs. This method can greatly reduce the loss of raw materials, improve the efficiency of the use of carbon fiber reinforced thermoplastics, and reduce the overall cost. In addition, compared with thermoset carbon fiber composites, CFRTP can shorten the molding cycle time due to its special process characteristics, which can further reduce the production cost in terms of productivity.

Carbon fiber reinforced thermoplastics vs. thermoset carbon fiber

The mechanical properties of carbon fiber reinforced thermoplastics also have advantages over thermoset carbon fiber composites. The density of thermoplastic carbon fiber composites is about 1.2g/cm, which is about 8 times lighter than steel, and even about 1/3 less than thermoset carbon fiber composites. This shows that carbon fiber reinforced thermoplastics have a great advantage in terms of specific strength and can withstand higher weight.

The working temperature of traditional thermoset carbon fiber is generally 150°C. With the increase of application fields, higher demands are made on carbon fiber composites, and the working temperature of CFRTP is several times higher than that of thermoset carbon fiber composites. CFRTP materials are more creep resistant and have higher dimensional stability in extreme environments. Due to the difference of matrix material, CFRTP has better friction resistance.

CFRTP molding method

The molding process of CFRTP includes compression molding, double film molding, hot press tank molding, vacuum bag molding, fiber winding molding, calendering molding, etc.

1、Double film molding

Double film molding is also called resin film infiltration molding, and this method is suitable for the molding process of parts with complex shape. The cut prepreg is placed between two layers of deformable flexible resin film and metal film, and the periphery of the film is sealed by metal or other materials. During the molding process, the prepreg is heated to the molding temperature, and then a certain molding pressure is applied, and the parts are deformed according to the shape of the carbon fiber mold, and then cooled and shaped.

In the double film molding, the part and the film are generally encapsulated and vacuumed. Since the membrane is deformable, it is more inclusive of resin flow; on the other hand, since the deformed membrane under vacuum can apply uniform pressure to the part, it can effectively improve the molding quality of carbon fiber composites.

2、Pultrusion molding

Pultrusion molding is a process method to continuously manufacture composite profiles with constant cross-section, which is to solidify the prepreg tape (yarn) in a set of pultrusion dies, and the prepreg is either prepreg while pultrusion or impregnated separately. Pultrusion molding can be used for the production of solid, hollow and various complex cross-sectional products, which can provide more room for designers to play due to its designability.

3、Compression molding

Compression molding is a way to lay the cut carbon fiber prepreg at a certain angle and number of layers, then put it into the mold, and put it into the hot press with the mold for heating and curing. The molding cycle is generally completed within a few tens of seconds to a few minutes. Compression molding method has low energy consumption, low cost and high productivity, and is more common in the molding process of carbon fiber reinforced thermoplastics.

4、Winding molding

The winding process of carbon fiber reinforced thermoplastics requires the carbon fiber prepreg to be heated to the softening point during winding, and then heated at the contact point of the core mold for curing. The available heating methods are conduction heating, dielectric heating, electromagnetic heating, electromagnetic radiation heating, etc.

Compression molding equipment and its mold structure are relatively simple and less expensive to manufacture, and MDC Mould has fully utilized its many years of experience in manufacturing compression molding molds for composite materials in the molding of CFRTP products. By using compression molding to make CFRTP parts, the loss of raw materials is smaller and does not cause excessive losses. When applied to mass production, the price can better meet the market demand compared to other carbon fiber molding processes.

In recent years, the application of high-performance thermoplastic resin composites in aerospace is developing rapidly, and many domestic and foreign aircraft manufacturing companies are using thermoplastic resin composites to manufacture aircraft components. MDC Mould is a high-end carbon fiber mold manufacturer, and has many years of experience in molding CFRTP composite products, if you need and want to know more about carbon fiber, please pay attention or call us.