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Innovative Spraying Process For CFRP Car Body Panels

Jun 11, 2020

Compare the surface finish with the spraying process

This innovative spraying process for CFRP car body panels

Highlights the use of online spraying process

Challenges faced in achieving Class A surfaces

It provides a process using PCM and SMC

New method of producing CFRP trunk lid

CFRP components used in the automotive industry should be produced using clear engineering steps and qualified production processes on appropriate equipment.

In the composite material industry, the autoclave process is often used to produce high-quality structural parts, but it also has its shortcomings. Therefore, it is necessary to adopt special solutions to meet the industry's demand for low-cost, high-quality production processes.

The new multi-material trunk lid developed by Hyundai Motor Group uses two new curing technologies (PCM and carbon fiber SMC) in its mass production. This component was used in the Genesis G70 sports car, a new luxury car of Hyundai Motor Group, which won the Motor Trend 2019 Best Car of the Year award.

The weight of the trunk lid is significantly reduced by 60%, which is 6.4kg lighter than the traditional steel structure, and the performance is good. The outer body panel uses 5 to 6 layers of unidirectional prepreg, and the inner panel uses 1.6 to 3.5mm thick carbon fiber SMC to locally reinforce several locations to reduce stress concentration.

The design concept has been evaluated based on finite element numerical analysis and a series of structural tests involving repeated opening/closing durability, dent resistance, and long-term environmental durability.

Its main advantages are:

►Online spraying of CFRP parts was realized in mass production, solving the problem of color matching;

►Adopt the traditional automotive spraying process to achieve A-level surface;

►Low-temperature curing of 2K transparent paint reduces energy consumption during spraying;

►Through design optimization, CFRP trunk lid can reduce weight by 60%;

►High cycle production of 5min cured PCM prepreg.

This innovation was achieved by introducing a new non-conductive primer (propylene olefin) and topcoat for spraying CFRP car body panels.

Subsequent tests showed that after automatic sandblasting and polishing, only a layer of primer was applied to the CFRP panel to eliminate the fiber texture. A thick layer of non-conductive primer can be sprayed online. By increasing the surface tension of the CFRP substrate, it has sufficient adhesion to the intermediate coating.

According to comprehensive factors, such as gloss, dullness and orange peel, the surface quality is equivalent to traditional steel parts.

New method of producing CFRP trunk lid

This innovation has been shortlisted in the finals of the JEC 2019 Innovation Awards car category.

The partners of Hyundai Motor Group are: Korea Hyundai Steel Corporation, Korea Hyundai Motor Group Polymer Research Laboratory, Japan Mitsubishi Chemical Corporation and Korea SK Chemical Corporation.