8466.91 - For machines of heading 8464:

HTS Code 8466.91 specifically pertains to parts and accessories designed for use with machines classified under heading 8464. Heading 8464 covers machine tools for working stone, ceramics, concrete, cement-like materials, glass, or other similar materials. Therefore, this subheading encompasses a wide array of components such as work or tool holders, chucks, vices, and other specialized attachments intended for use with these stone, glass, and ceramic working machines.

This category is distinguished from its siblings by its exclusive focus on machinery for working the aforementioned materials. For instance, 8466.92 covers parts for machines used in working wood, cork, bone, hard rubber, hard plastics, or similar hard materials (heading 8465), while 8466.93 is for parts related to metalworking machinery (headings 8456 to 8461). Similarly, 8466.94 deals with parts for metal-forming machinery (headings 8462 or 8463).

Within HTS 8466.91, further subdivisions exist to refine classification based on material and processing. The subcategory 8466.91.10.00 is reserved for cast-iron parts that have undergone only basic cleaning or minimal machining for fitment. The broader subcategory 8466.91.50.00 captures all other parts and accessories not meeting the specific criteria of the preceding subcategory, offering a catch-all for the diverse range of components used with heading 8464 machinery.