19 CFR § 10.16 - Assembly abroad.
(a) Assembly operations. The assembly operations performed abroad may consist of any method used to join or fit together solid components, such as welding, soldering, riveting, force fitting, gluing, laminating, sewing, or the use of fasteners, and may be preceded, accompanied, or followed by operations incidental to the assembly as illustrated in paragraph (b) of this section. The mixing or combining of liquids, gases, chemicals, food ingredients, and amorphous solids with each other or with solid components is not regarded as an assembly.
(b) Operations incidental to the assembly process. Operations incidental to the assembly process whether performed before, during, or after assembly, do not constitute further fabrication, and will not preclude the application of the exemption. The following are examples of operations which are incidental to the assembly process:
(2) Removal of rust, grease, paint, or other preservative coating;
(3) Application of paint or preservative coating, including preservative metallic coating, lubricants, or protective encapsulation;
(4) Trimming, filing, or cutting off of small amounts of excess materials;
(5) Adjustments in the shape or form of a component to the extent required by the assembly being performed abroad;
(6) Cutting to length of wire, thread, tape, foil, and similar products exported in continuous length; separation by cutting of finished components, such as prestamped integrated circuit lead frames exported in multiple unit strips; and
(7) Final calibration, testing, marking, sorting, pressing, and folding of assembled articles.
(c) Operations not incidental to the assembly process. Any significant process, operation, or treatment other than assembly whose primary purpose is the fabrication, completion, physical or chemical improvement of a component, or which is not related to the assembly process, whether or not it effects a substantial transformation of the article, will not be regarded as incidental to the assembly and will preclude the application of the exemption to such article. The following are examples of operations not considered incidental to the assembly as provided under subheading 9802.00.80, Harmonized Tariff Schedule of the United States (19 U.S.C. 1202):
(1) Melting of exported ingots and pouring of the metal into molds to produce cast metal parts;
(3) Chemical treatment of components or assembled articles to impart new characteristics, such as showerproofing, permapressing, sanforizing, dying or bleaching of textiles;
(4) Machining, polishing, burnishing, peening, plating (other than plating incidental to the assembly), embossing, pressing, stamping, extruding, drawing, annealing, tempering, case hardening, and any other operation, treatment or process which imparts significant new characteristics or qualities to the article affected.
(d) Joining of American-made and foreign-made components. An assembly operation may involve the use of American-made components and foreign-made components. The various requirements for establishing entitlement to the exemption apply only to the American-made components of the assembly.
(e) Subassembly. An assembly operation may involve the joining or fitting of American-made components into a part or subassembly of an article, followed by the installation of the part or subassembly into the complete article.
(f) Packing. The packing abroad of merchandise into containers does not in itself qualify either the containers or their contents for the exemption. However, assembled articles which otherwise qualify for the exemption and which are packaged abroad following their assembly will not be disqualified from the exemption by reason of their having been so packaged, whether for retail sale or for bulk shipment. The tariff status of the packing materials or containers will be determined in accordance with General Rule of Interpretation 5, HTSUS (19 U.S.C. 1202).