Brake discs are primarily made from cast iron and carbon additives. Carbon offers high thermal resistance and light weight, but its high cost restricts its use to high-budget racing teams. Cast iron, the more commonly used material, comes in three types based on their graphite content: grey cast iron, CV cast iron, and ductile cast iron.
Grey cast iron, also known as flake graphite cast iron, is popular due to its excellent malleability, anti-abrasion properties, and ease of mass production. However, it can deform or crack under repeated, sharp temperature changes at high temperatures (around 800℃).
Ductile cast iron, with tensile strength comparable to steel, also boasts high thermal stability. However, its low surface hardness and high exothermicity can lead to abnormal wear and heating, making it less suitable for brake discs.
CV cast iron, or compacted vermicular cast iron, has characteristics between grey and ductile cast iron. Its manufacturing quality control is challenging, leading to variability; sometimes it resembles grey cast iron, and other times ductile cast iron.
After extensive testing, Brake X uses grey cast iron with special additives for enhanced durability and resistance to temperature changes. While OEM products often use grey cast iron with a strength rating of FC150-200, Brake X opts for FC200-250 for higher durability. The result is a disc with superior precision, balance, and improved resistance to sharp temperature fluctuations.