【104】Let Chinese automobiles have a "breathing" composite skeleton - the Golden Eagle multi-material forming technology redefines lightweight strength.

【104】Let Chinese automobiles have a "breathing" composite skeleton - the Golden Eagle multi-material forming technology redefines lightweight strength.

This afternoon, the evaluation panel from Changchun FAW spent a full forty minutes in the workshop, just to watch the gas-assisted injection molding machine complete a forming cycle for an automotive door handle frame. When the mechanical hand gently placed the shiny composite part on the inspection table, the chief engineer in charge of the chassis system personally picked up the micrometer to measure, and then turned to the team and said, "The wall thickness difference is 0.15 millimeters, and there are no bubbles at the plastic-metal bonding surface - this is the integrated molding solution we have been searching for for three years."

I remember the first time I came into contact with this project was in early snow last year. The engineers from FAW brought two heavy suitcases to Dongguan, filled with various failed samples: those with loose bolts connections, those that broke during winter tests, and those that made abnormal sounds due to thermal expansion and contraction. The young engineer with glasses almost pleaded, "Jeannie, our electric vehicle will undergo winter tests in Harbin at minus thirty degrees. Traditional injection molded parts failed in the low-temperature brittleness test. The German supplier said we must use metal frames, but the weight and cost were unbearable."

I asked the technical team to analyze those fracture surfaces immediately. The specific reasons soon emerged: First, the difference in thermal expansion coefficients between plastic and metal causes a 0.2 millimeter gap at a temperature difference of 60 degrees; second, the interface stress concentration in traditional insert injection molding makes the bonding strength only 40% of the theoretical value; third, the long melt flow length in complex parts causes the temperature to drop to the crystallization point before reaching the end. That night, we held an emergency meeting, and the process supervisor, Mr. Wang, proposed a bold idea: "Why not try combining gas-assisted injection molding with laser activation? Let the nitrogen gas open micro channels in the melt, and use laser to etch nano-scale inverted hook structures on the metal surface."

But this path was too difficult to follow. During the first mold trial, the uneven gas penetration caused the product to be full of bubbles like a honeycomb. The second time, the laser parameters on the metal surface were not adjusted properly, and the plastic could not stick at all. The most desperate was the third time, even though all the data met the standards, the sample cracked at the bonding surface during the vibration test. That night at eleven o'clock, the laboratory was terrifyingly quiet. The young materials engineer, Xiao Chen, suddenly said, "Are we too superstitious about data? The multi-axis vibration in actual working conditions is completely different from our single-directional tests."

This sentence woke everyone up. We worked overnight to modify the test bench to simulate the six degrees of freedom of the car's compound vibration in a bumpy road. Sure enough, under this real working condition, the traditional flat bonding method couldn't withstand it. The solution eventually came from an unexpected discovery - the engineer from the medical device company suggested borrowing the "bone trabeculae" structure of human bones and designing a three-dimensional interlocking network at the plastic-metal interface. This idea led us to invest three more months in developing the porous gradient composite technology: a rigid support grid near the metal side, a buffer transition layer in the middle, and a resilient coating layer on the outer layer.

In March this year, the first door handle frames were installed on the vehicle and sent to Harbin. In the extremely cold environment of minus thirty-five degrees Celsius, the test vehicle continuously traveled 5,000 kilometers, and the frame remained intact. The video sent by FAW showed that the chief engineer, Mr. Zhang, excitedly said on the ice and snow test track, "It is 40% lighter than the German solution, and the cost is only one-third of theirs, but the strength test data is still 15% higher." At the end of the video, he pointed his thumb at the camera, "This is the中国制造we need."

Now， this technology is not only used in door handles but has also expanded to fifteen key structural components of the entire vehicle. Last week， FAW sent a cooperation intention for a new project - they are developing a hydrogen fuel cell vehicle that needs a composite hydrogen storage tank bracket that can withstand a temperature difference of minus fifty to one hundred and twenty degrees Celsius. This story begins with the broken samples in the suitcase, and gains answers in the extremely cold environment of the ice test track. As more and more Chinese electric vehicles adopt this "bone trabecular" like composite structure, the previously troublesome problems such as abnormal noises, fractures and loosening that plagued the industry are being solved one by one by the engineers of a factory in Dongguan through innovation.

Let Chinese automobiles have a "breathing" composite skeleton - the Golden Eagle multi-material forming technology redefines lightweight strength.