Why is high-chromium cast iron used for the liner of a Raymond mill?

High-chromium cast iron (Cr15~Cr26) is widely used for Raymond mill liners in the industry, rather than ordinary steel plates or high manganese steel, primarily based on the following two considerations.

Wear Resistance of Cast Iron Liners Matches Raymond Mill Wear Conditions

The liner is fixed on the inner side of the housing and mainly withstands two types of wear: one is high-stress abrasive wear, where hard particles press into the liner surface during the grinding of materials between the grinding rollers and rings, causing cutting wear. The other is erosion wear, where airflow carries fine powder at high speed across the liner surface, especially near the air duct. Subjected to dual wear conditions, the primary performance requirement is extreme wear resistance to protect the housing from wear.

Ordinary steel plates have a hardness of only HRC 20~30, and if used as liners, they will develop obvious grooves within weeks. High-chromium cast iron has a hardness of HRC 58~65, with M7C3-type carbides (hardness HV 1800~2200) dispersed in the matrix forming a micro wear-resistant skeleton. It maintains high hardness without impact, with wear resistance approximately 5~8 times that of ordinary steel plates.

In contrast, high manganese steel relies on work hardening through strong impact (requiring impact energy to increase its surface hardness from HB200 to over HB500). During the operation of a Raymond mill, the liner is subjected to relatively low impact, so high manganese steel cannot be fully hardened, and its wear resistance is actually lower than that of ordinary carbon steel.

High Cost-Effectiveness of Cast Iron Liners for Raymond Mills

Although the unit purchase cost of cast iron liners is slightly higher than that of ordinary steel plates, their total lifecycle cost is significantly lower than that of ordinary steel plates. Ordinary steel plate liners typically need replacement after 1~2 months of continuous operation, while high-chromium cast iron liners have a service life of 6~12 months, resulting in lower maintenance downtime and facilitating continuous production of the Raymond mill.

It should be noted that high-chromium cast iron has relatively poor toughness; if high-hardness foreign objects such as iron blocks or bolts are mixed into the material, brittle fracture may occur. Therefore, production lines are typically equipped with magnetic separators for iron removal.