Magnesium vs Plastics in  Two-Wheelers 

Manufacturing Constraints:

• Thin-wall (<1.8 mm) magnesium die casting faces low yield (≈ < 75%) due to solidification enthalpy and low specific heat.

• Thixomolding equipment costs 10× more than plastic injection machines (¥8–12 million per unit).

• Mold life is only 50–80 k shots vs. 500 k for plastic molds, making it uneconomic at mid-volume scale.

Electrochemical and Thermal Mismatch:

• Magnesium’s standard electrode potential: −2.37 V. In muddy electrolytic environments, it acts as a sacrificial anode, corroding rapidly when in contact with steel without insulation or MAO protection.

• Above 350 °C, its oxide film turns porous, and heat release peaks 3–5× that of aluminum. If lithium battery thermal runaway exceeds 800 °C, ignition risk arises, leading OEMs to prefer flame-retardant plastics for compliance safety.

Competitive Landscape:

• High-vacuum die-cast aluminum (AlSi10MnMg T6) now surpasses AZ91D in strength and doesn’t require corrosion coating.

• Carbon fiber (CFRP) achieves 1.5–2× specific stiffness; with domestic T700 fiber cost near ¥200/kg, high-end E-bikes are shifting toward composite molding.

FMEA Logic:

• Failure in electrochemical isolation → structural collapse.

• Thin-wall casting yield < 80% → cost erosion cancels weight advantage.

• Recycled alloy contamination (Fe/Ni > 0.005%) → exponential corrosion decay and warranty risks.

Case Study:
A brand deployed  magnesium in an e-motorbike battery cover to minimize weight. Hot gas from cell venting triggered violent oxidation—failed thermal audit. Solution: add insulation or revert to flame-retardant plastic.

Strategic Insight:
Instead of seeking “plastic substitution,” magnesium alloys should target the irreplaceable 10%:

• High-damping parts (motor housings, suspension modules) to leverage ≈ 10× damping vs. aluminum.

• Electromagnetic shielding shells (BMS/control enclosures) with 80–100 dB shielding efficiency.

Aikerly Recommendation:
Before mass production, conduct a Lightweight Risk Audit to assess corrosion, insulation, and thermal flux compatibility—preventing failure costs later.