The molding process of high-performance thermoplastic composite materials is mainly transplanted from thermosetting resin composite materials and metal molding technology. According to the different equipment, it can be divided into compression molding, double film molding, autoclave molding, vacuum bag molding, fiber winding molding, calender molding, etc. Among these methods, Hay Think will select 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 composite materials.
1. Double film forming
Double-membrane molding is also called resin film infiltration molding. It is a method developed by ICI to prepare composite parts using prepregs. This method is conducive to the molding and processing of parts with more complex shapes.
In double film molding, the cut prepreg is placed between two layers of deformable flexible resin film and metal film. The periphery of the film is sealed with metal or other materials. During the molding process, it is heated to the molding temperature and applied With a certain molding pressure, the part deforms according to the shape of the metal mold, and is finally cooled and shaped.
In double-film forming, the parts and films are generally encapsulated and vacuumed. Due to the deformability of the film, the restriction on resin flow is much smaller than that of rigid molds. On the other hand, the film deformed under vacuum can apply uniformity to the part. Pressure can increase the degree of pressure change of the part and ensure the quality of molding.
2. Pultrusion
Pultrusion is a process for continuously manufacturing composite profiles with constant cross-sections. It was originally used to manufacture simple products with unidirectional fiber-reinforced solid cross-sections, and gradually developed into products that can manufacture solid, hollow and various complex cross-sections. The performance of the profile can be designed to meet the requirements of various engineering structures.
Pultrusion is to consolidate the prepreg tape (yarn) in a set of pultrusion molds. The prepreg is either pre-impregnated while pultruding or otherwise impregnated. The general impregnation method is fiber blend impregnation and powder liquidized bed impregnation.
3. Compression molding
Compression molding is to heat the prepreg sheet cut according to the size of the mold to a temperature higher than the melting temperature of the resin in a heating furnace, and then send it into a large compression mold for rapid hot pressing. The molding cycle is generally completed within tens of seconds to several minutes. This molding method has low energy consumption and production costs, and has high productivity. It is currently the most common molding method in the molding and processing of thermoplastic composite materials.
4. Winding forming
The difference between the filament winding molding of thermoplastic composites and thermosetting composites is that the prepreg yarn (tape) is heated to the softening point during winding and heated at the contact point of the core mold.
Common heating methods include conduction heating, dielectric heating, electromagnetic heating, electromagnetic radiation heating and so on. In electromagnetic radiation heating, infrared radiation (IR), microwave (MW) and radio frequency (RF) heating are divided into different wavelengths or frequencies of electromagnetic waves. In recent years, laser heating and ultrasonic heating systems have also been developed.
In recent years, a new type of winding molding process has been developed. Among them, there is a one-step molding method, that is, the fiber is made into a prepreg yarn (tape) through a thermoplastic resin powder boiling fluidized bed, and then directly wound on the core mold; The carbon fiber prepreg yarn (tape) is directly energized, and the thermoplastic resin is melted by the electricity to generate heat, and the fiber yarn (tape) is wound into a product; the third type is to use a robot to wind the product to improve the accuracy and automation of the winding product, which is greatly affected. Attention.