BYD has shared new technical details on its official Weibo account about the one-piece aluminium frame used in the Yangwang U8L, outlining a development program that began in 2023 and led to the creation of what the company described as China’s largest automotive integrated casting machine in collaboration with aerospace-focused supplier Hantek.
The latest disclosure provides additional insight into a technology previously highlighted when the Yangwang U8L was introduced with what BYD said was the world’s first one-piece low-pressure-cast aluminium vehicle frame. The structure features a 4.2-square-meter integrated casting with wall thicknesses ranging from 4 mm to 50 mm, presenting manufacturing challenges that the company said had previously exceeded the capabilities of conventional automotive casting methods.
Focus on Replacing Traditional Steel Structures
According to BYD engineers, the project was aimed at developing a full-size vehicle frame capable of surpassing traditional steel structures in areas including weight reduction, strength, corrosion resistance and durability. Engineers evaluated several material options, including high-strength steel, hot-formed steel, titanium alloys and aluminium alloys, before selecting aluminium as the material best suited to meeting the project’s objectives under current production conditions.
The company said the frame incorporates aerospace-grade 6-series and 7-series aluminium alloys alongside a highly integrated structural design intended to maximize rigidity while reducing mass. Engineers also concluded that achieving the desired structural performance would require both large-scale integrated casting and a significant reduction in heat-affected zones created during welding. This led the development team to adopt cold-joining techniques, including bolting and riveting, methods commonly used in aerospace applications.
Aerospace Manufacturing Techniques Adapted for Automotive Use
BYD said suitable casting equipment was not available when the project started. After conventional multi-piece rear-casting solutions failed to consistently meet stress-testing requirements, the company sought expertise beyond the automotive sector and partnered with Hantek to develop a new manufacturing system.
The resulting process became what BYD described as the first domestic application of integrated low-pressure casting technology for a large vehicle frame. The company said the number of components was reduced from 251 to 119, while 67 rear-frame parts were consolidated into a single casting. Weld length was reduced from approximately 100 meters to 9 meters, helping lower the number of potential fatigue and deformation points.
Engineers also adopted aerospace-derived dimensional-chain control techniques to improve bolt preload distribution and connection reliability under dynamic loading conditions. BYD said key connection-point performance improved more than fourfold, while tensile performance more than doubled compared with earlier development stages. The completed aluminium frame reduced vehicle weight by 56 kg while increasing structural rigidity.
Structural Performance and Brand Positioning
According to the company, the Yangwang U8L became “the first vehicle in the industry to pass a 12-ton lifting test using the integrated frame structure.” BYD added that the vehicle’s torsional rigidity exceeds that of comparable models by more than 50%.
The disclosure comes as Yangwang continues to serve as a technology showcase for BYD. At the 2026 Beijing Auto Show, the brand displayed special versions of the U8L and U9 Xtreme. The limited-production U9 Xtreme later became the most expensive vehicle sold by BYD, with a reported price of 20 million yuan ($2.76 million).