The forming technology of high performance thermoplastic composites is mainly transplanted from thermosetting resin composites and metal forming technology. According to different equipment, it can be divided into molding, double film molding, autoclave molding, vacuum bag molding, filament winding molding, calendering molding, etc. In these methods, we will choose a few more used molding methods to give you a brief introduction, so that you can have a more comprehensive understanding of thermoplastic carbon fiber composites.
1. Double film forming
Double membrane molding, also known as resin membrane infiltration molding, is a method developed by ICI company to prepare composite parts with prepreg. This method is conducive to the molding and processing of complex parts.
In double film forming, the cut prepreg is placed between two layers of deformable flexible resin film and metal film, and the periphery of the film is sealed with metal or other materials. In the forming process, after heating to the forming temperature, a certain forming pressure is applied, and the parts are deformed according to the shape of the metal mold, and finally cooled and shaped.
In the process of double film forming, the parts and films are usually packaged and vacuumized. Due to the deformability of the film, the restriction of resin flow is far less than that of the rigid mold. On the other hand, the deformed film under vacuum can exert uniform pressure on the parts, which can improve the pressure variation of the parts and ensure the forming quality.
2. Pultrusion molding
Pultrusion is a continuous manufacturing process of composite profiles with constant cross-section. Initially, it was used to manufacture simple products with unidirectional fiber reinforced solid cross-section, and gradually developed into products with solid, hollow and various complex cross-sections. Moreover, the properties of profiles can be designed to meet the requirements of various engineering structures.
Pultrusion molding is to consolidate the prepreg tape (yarn) in a group of pultrusion molds. The prepreg is either pultruded and prepreg, or impregnated separately. The general impregnation methods are fiber blending impregnation and powder liquefying bed impregnation.
3. Pressure Molding
The prepreg sheet is cut according to the size of the mold, heated in the heating furnace to a temperature higher than the melting temperature of the resin, and then sent to the large die for rapid hot pressing. The molding cycle is usually completed in tens of seconds to a few minutes. This kind of molding method has low energy consumption, low production cost and high productivity. It is the most common molding method in the molding process of thermoplastic composites.
4. Winding forming
The difference between filament winding of thermoplastic composites and thermosetting composites is that the prepreg yarn (tape) should be heated to the softening point and heated at the contact point of the mandrel.
The common heat methods include conduction heating, dielectric heating, electromagnetic heating, electromagnetic radiation heating, etc. In the heating of electromagnetic radiation, infrared radiation (IR), microwave (MW) and RF heating are also divided due to the different wavelength or frequency of electromagnetic wave. In recent years, laser heating and ultrasonic heating system have also been developed.
In recent years, new winding process has been developed, including one-step molding method, that is, the fiber is made into prepreg yarn (tape) by boiling liquefaction bed of thermoplastic resin powder, and then directly wound on the mandrel; In addition, through the heating forming method, that is, the carbon fiber prepreg yarn (tape) is directly electrified, and the thermoplastic resin is melted by electrifying and heating, so that the fiber yarn (tape) can be wound into products; The third is to use robot to winding, improve the accuracy and automation of winding products, so it has received great attention.
Post time: Jul-15-2021