Materials and Manufacturing Technologies for Environmental Compatibility and Mass Production Toward Widespread Use of CFRP

Carbon fiber reinforced plastics (CFRP) are attracting attention as a trump card for lightweight materials for transportation equipment, but mass production of CFRP has not progressed as expected due to various challenges, such as the high material cost of carbon fiber and the difficulty of designing, manufacturing, and reusing CFRP products. In this paper, taking into account the recent environment, materials, manufacturing methods, and application trends surrounding CFRP, an example of an innovative manufacturing technology suitable for the mass production of a series of thermoplastic CFRP parts that the authors have been developing in recent years is introduced, and the deepening and harmonization of design technology and processing technology is discussed. The main feature of the process introduced in this paper is that it forms a reinforcement form by forming a grid structure from continuous thermoplastic CFRP rods manufactured by pultrusion molding or continuous compression molding, rather than a laminated structure by layup manufacturing using CFRP sheets, which has been widely used in the past. Such continuous thermoplastic CFRP rods are assembled by a hybrid joint that combines fusion joining and thermoplastic CFRP riveting after hot forming with a small servo press, insert injection molding, and hot press molding. The advantages of this process are high productivity, low cost, and excellent reusability. The authors have already prototyped a thermoplastic CFRP battery cover using this manufacturing method, and each step of the manufacturing method will be described based on the development example.