7325.91.00.00 - Grinding balls and similar articles for mills

This HTS category, 7325.91.00.00, specifically covers grinding balls and similar articles used in mills. These items are designed for the process of grinding or crushing materials within milling equipment. They are typically made of cast iron or cast steel and their primary function is to facilitate the reduction of particle size through mechanical attrition. Examples include grinding media used in ball mills or rod mills for processing minerals, cement, or other industrial materials.

While the broader heading 7325 encompasses "Other cast articles of iron or steel," and the subheading 7325.9 covers "Other" cast articles, this specific 8-digit code carves out a distinct group based on their specialized function. The sibling category, 7325.99, covers all other cast articles of iron or steel not specifically enumerated elsewhere, meaning it would include cast iron or steel items with different uses or functionalities than grinding media.

As this is a leaf node within the HTS, there are no further subcategories. Therefore, classification within 7325.91.00.00 relies on the definitive criteria of the article being a cast iron or steel ball or a similar article designed and used for grinding or milling purposes. The key distinguishing factor remains its intended application within milling machinery.