Carbon fiber-reinforced plastic (CFRP) has the advantages of being light weight, high strength, and corrosion resistant. At present, it is widely used in the lightweight design of automobile parts. The manufacturing of lightweight parts inevitably involves the connection between CFRP and the polymer material. The connection strength between CFRP and the polymer material significantly affects the service life of the composite parts. Taking CFRP and polyamide 6 (PA6) injection-molded composite parts as an example, this paper proposed a technological method to enhance the connection strength between CFRP and PA6. The proposed method was to fabricate micro-groove structures on the CFRP surface by compression molding. These micro-groove structures effectively increased the injection-molding area of the composite parts, thus enhancing the connection strength between CFRP and PA6. This paper presented a detailed study on the compression-molding process of micro-grooves on the CFRP surface, and successfully obtained the appropriate parameters. Finally, PA6 was used for injection molding on the CFRP with micro-grooves at an injection pressure of 8 MPa, an injection temperature of 240 °C, a holding pressure of 5 MPa, and a holding time of 2.5 s. The experimental results show that the micro-groove array structures on the CFRP surface could effectively improve the tensile strength of the connection interface in the composite parts. Compared with the composite part without micro-grooves, the tensile strength of the composite part with micro-grooves was increased by 80.93%. The composite parts prepared in this paper are mainly used in automobile interiors and the research results of this paper meet the actual needs of the enterprise.
Keywords: carbon fiber composite; composite part; connection strength; micro-groove; polyamide 6.