How does aluminum extrusion technology enable the one-piece molding of complex cooling channels within an aluminum extruded battery tray?
Publish Time: 2025-10-02
In the heart of a new energy vehicle—the battery pack—the battery tray is no longer merely a "support frame" for the battery modules; it has evolved into an intelligent carrier integrating structure, heat dissipation, and protection. Among these, liquid-cooled battery trays manufactured via aluminum extrusion stand as a leading technology due to their superior heat dissipation and lightweight design. Most remarkably, the intricate cooling channels running throughout the tray are formed integrally with the main structure, eliminating the need for post-processing welding or joining. How is this seemingly impossible complex structure achieved through aluminum extrusion? The answer lies in the flow of the material and the ingenuity of the mold design.
Aluminum extrusion involves heating an aluminum alloy billet, placing it in a die, and forcing it through a specific-shaped mold under hydraulic pressure to produce a continuous, long, profiled section. Traditionally, extrusion was used for simple cross-section profiles like window frames and heat sinks. However, modern high-precision extrusion technology can now produce highly complex hollow structures. The key lies in the mold design and the use of internal mandrel supports.
The cooling channels in a battery tray are typically narrow, multi-channel, and even have internal partitions, running the entire length of the tray. To achieve these cavities in one-step molding, the mold must have a "negative" shape corresponding precisely to the channel geometry. These structures, made of high-strength alloy steel, are suspended in the center of the mold channel, acting as "bridges" or "flow dividers." Under high pressure, the molten aluminum flows from all sides, guided by the flow dividers, merges, and welds together, encapsulating the mandrel. Finally, at the exit, it forms a complete profile, with the space occupied by the mandrel becoming the internal cooling channel.
This process demands extremely uniform metal flow. If the molten aluminum temperature is too low or the pressure insufficient at the merging point, complete welding cannot occur, resulting in "weld defects" and poor sealing of the cooling channels. Therefore, the billet must be heated to a precise temperature range before extrusion to ensure good plasticity and fluidity. The mold itself requires a complex design of flow channels and welding chambers to guide the molten aluminum at the appropriate speed and angle, promoting grain coalescence and forming a dense metallurgical bond.
The cross-sectional shape of the cooling channels can be flexibly designed; round, flat, serpentine, or even complex shapes with turbulence-inducing structures can be achieved through customized mold design. The location, number, and distribution of the channels can be optimized based on the thermal requirements of the battery module, ensuring even heat dissipation. Because it is a one-piece molding process, the inner wall of the channel is smooth with no weld seams or protrusions, reducing fluid resistance and the risk of clogging.
After extrusion, the long extruded profile is cut to the length of the battery tray, and subsequent processes such as end-plate sealing, surface treatment, and sealing tests are performed to produce the finished liquid-cooled tray. Throughout the process, the cooling channels remain completely enclosed within the aluminum structure, eliminating the risk of leaks and machining errors associated with drilling and welding.
Ultimately, achieving one-piece molding of complex cooling channels through aluminum extrusion is a symphony of materials science and precision manufacturing. It combines the plasticity of molten metal with the precision of mold design, allowing both "hollow" and "solid" structures to be formed simultaneously. As the coolant flows silently through the seamless channels, carrying away the heat generated by the battery, it reflects the profound understanding of metal flow by mold engineers and the relentless pursuit of "integration" and "reliability" in modern manufacturing.
