Ferrous foundries (NAICS 33151) cast iron and steel, producing parts with high strength and wear resistance suited for heavy machinery, pipe fittings, and automotive components. Nonferrous foundries (NAICS 33152) cast metals such as aluminum, zinc, and copper alloys, favoring lighter weight, corrosion resistance, and tighter dimensional tolerances. The distinction drives both HTS classification of the finished casting and the applicable trade-remedy landscape, as antidumping orders tend to be metal-specific.

Casting classification in the HTS depends on the metal composition (iron, steel, aluminum, copper, etc.), the casting method (sand cast, die cast, investment cast), and the article's end use or form. Because castings appear across multiple HTS chapters — from Chapter 73 (iron and steel articles) to Chapter 76 (aluminum) and beyond — importers should obtain a binding ruling from CBP or consult a licensed customs broker when the classification is not straightforward, especially where trade-remedy orders may apply.