Are BMW 3 Series Wheels Cast or Forged?

[McLawson]

BMW 3 Series wheels are manufactured using the casting method. Below is an introduction to three casting methods: Gravity Casting Method: This method utilizes gravity to pour aluminum alloy solution into a mold. After forming, the product undergoes lathe processing and polishing to complete production. The manufacturing process is relatively simple, requiring no precise casting techniques, resulting in low costs and high production efficiency. However, it is prone to bubbles (sand holes), uneven density, and insufficient surface smoothness. Forging Method: An entire aluminum ingot is directly extruded into shape on a mold using a thousand-ton press. The advantages include uniform density, smooth and detailed surface finish, thin and lightweight wheel walls, and the highest material strength—30% higher than casting methods. Low-Pressure Precision Casting Method: This method involves precision casting under low pressure of 0.1Mpa. It offers excellent formability, clear contours, uniform density, and a smooth surface. It achieves high strength and lightweight while controlling costs, with a yield rate of over 90%.