Li Auto's magnesium alloy one-piece die-cast rear floor has won a Gold Casting Award at CHINA DIECASTING 2026 in Shanghai and is already in series production, according to reports published on July 30 and 31, 2026. The part was jointly developed with supplier Changzhou Duoli Automotive Technology. Li Auto also took a second Gold Casting Award for a high-performance five-in-one electric drive housing, making it the only vehicle OEM to win the expo's top casting honor this year.
CHINA DIECASTING 2026 ran July 15–17 at the Shanghai New International Expo Centre. It is Asia's largest die casting exhibition, and the Gold Casting Award is its highest recognition for cast parts. Large one-piece castings at previous editions were overwhelmingly aluminum. A magnesium rear floor winning — and shipping on production vehicles — marks a first for the material at this scale.
What Li Auto Won For
The rear floor is the load-bearing structure under a vehicle's third row and trunk. Producing it as a single magnesium high-pressure die casting means solving problems that have kept large magnesium structural parts at the sample stage for years: porosity and hot cracking in large thin-wall sections, stable filling over a meter-scale flow path, and corrosion protection.
Li Auto's approach combined a self-developed magnesium alloy with structure and process optimization matched to the part's load paths. The reported results: part toughness up 10% and casting fluidity up 40% against the baseline, enough to move a large thin-wall magnesium casting into stable volume production. Replacing a multi-piece welded structure with one casting also raises body stiffness, while the weight saving feeds directly into energy consumption and range, and magnesium's natural damping improves chassis NVH.
The second award went to a five-in-one electric drive housing, another magnesium part where wall thickness, sealing, and heat resistance set the difficulty.
Key Numbers
| Item | Detail |
|---|---|
| Winning parts | Magnesium one-piece rear floor; five-in-one e-drive housing |
| Award | Gold Casting Award, CHINA DIECASTING 2026 (Shanghai, July 15–17) |
| Development partner | Changzhou Duoli Automotive Technology |
| Part toughness | +10% |
| Casting fluidity | +40% |
| Production status | In series production |
| Magnesium density | ~1.8 g/cm³, roughly one-third lighter than aluminum |
Why Magnesium, and Why Now
Magnesium's case is straightforward: at about 1.8 g/cm³ it is two-thirds the density of aluminum and a quarter that of steel, with good damping and electromagnetic shielding. What held it back was never performance. Cost, process safety in the melt shop, and corrosion resistance were the three barriers, and all three have weakened. The magnesium-to-aluminum price ratio has fallen to roughly 0.8:1, so the raw material is now cheaper per kilogram than aluminum, not just lighter. Semi-solid and improved HPDC processes have made production safer and more stable, and modern coating systems handle the corrosion question on underbody parts.
The automotive context matters too. One-piece aluminum castings proved that 60 to 80 stamped and welded parts can become a single casting, but aluminum gigacasting is nearing its practical weight floor. Magnesium offers the next step down in density, and industry commentary has framed it as the natural successor for the second generation of integrated castings. Li Auto's rear floor is the clearest evidence so far that the step is producible, not just demonstrable.
What It Means for Casting Buyers
Two takeaways stand out for engineers and sourcing teams watching this space.
- Material options for lightweight parts are widening. The practical choice set for structural castings used to be aluminum or steel. Magnesium now has a mass-production reference at the largest part size, which will pull it into RFQ discussions for smaller brackets, housings, and e-drive components where its density and damping pay off.
- Process capability decides material feasibility. Magnesium punished weak process control for decades. The same is true of aluminum: porosity, filling balance, and melt quality determine whether any alloy performs to its datasheet. Supplier evaluation should start from equipment, process monitoring, and inspection capability, then move to material.
That second point is where we spend our own production effort. Meituo's aluminum die casting programs for appliance, automotive, and industrial customers run on in-house mold design, spectrometer melt verification, and X-ray inspection, because consistent metal quality is what lets a lightweight design survive contact with the real world. The full equipment and inspection setup is on our manufacturing capabilities page.
Sources
- Shanghai Metals Market (SMM), July 30, 2026 — Li Auto magnesium die-cast rear floor wins Gold Casting Award and reaches mass production
- Die Casting Weekly, July 31, 2026 — Li Auto wins two Gold Casting Awards at CHINA DIECASTING 2026; toughness +10%, fluidity +40%
- NetEase (Jingzhu Laoshiji column), July 29, 2026 — magnesium-aluminum price ratio falls to around 0.8:1; magnesium positioned to benefit from gigacasting adoption
- Aibang Robotics, August 3, 2026 — magnesium alloy adoption analysis: semi-solid die casting progress and lightweighting drivers
