8459.51.00 - Numerically controlled

HTS Code 8459.51.00 specifically classifies numerically controlled milling machines of the knee-type. These machines are designed for metalworking operations such as milling, drilling, and boring, characterized by their advanced computer numerical control (CNC) systems that automate the cutting processes based on pre-programmed instructions. The "knee-type" designation refers to the vertical adjustment capability of the milling head and table assembly, providing versatility in workpiece positioning and machining configurations.

This category is distinguished from its sibling, 8459.59.00, which covers "other" milling machines of the knee type. While both fall under the broader heading for milling machines, 8459.51.00 is exclusively for those equipped with numerically controlled systems. Sibling 8459.59.00 would therefore encompass manually operated or less automated knee-type milling machines.

Within 8459.51.00, further distinctions are made to refine the classification. The subcategories 8459.51.00.40 and 8459.51.00.80 allow for a more granular breakdown, with the former specifying "used or rebuilt" machines. This distinction is crucial for duty and regulatory purposes, recognizing the different economic and operational status of pre-owned equipment compared to new machines. The remaining subcategory, "other," captures any numerically controlled knee-type milling machines not otherwise specified.