8456.90 - Other:

Category 8456.90 encompasses "Other" machine tools that operate by material removal processes not specifically enumerated in preceding subheadings. This broadly includes machinery utilizing methods like electro-chemical, electron-beam, ionic-beam, or other specialized plasma arc processes for working various materials. The key differentiator from sibling categories lies in the specific energy or process employed; for instance, it excludes machines operated by laser, ultrasonic, or electro-discharge, which are found in 8456.10, 8456.20, and 8456.30 respectively. Water-jet cutting machines are also separately classified under 8456.50.00.00.

Within this "Other" category, further distinctions are made based on the material being worked and the specificity of the process. Subcategory 8456.90.31.00 is dedicated to machines specifically designed for working metal, highlighting the material as a primary classification factor. The remaining "Other" machines, classified under 8456.90.71.00, cover a diverse range of applications and materials where the specific process might be less common or not explicitly detailed in the preceding headings, but still falls within the broader scope of material removal via non-laser, non-ultrasonic, and non-electro-discharge methods.