Chapter 84 is the core chapter in the HS classification covering machinery and mechanical appliances, including power machinery, metalworking machine tools, industrial robots, office equipment, refrigeration equipment, etc. Its scope ranges from simple hand tools to highly complex automated production lines, with the core characteristic being the use of mechanical motion to perform work or processing. This chapter emphasizes the functional principle of machines rather than specific industry uses, so the same chapter may include cross-sector equipment such as textile machinery, papermaking machinery, and printing machinery. Understanding Chapter 84 requires grasping the essence of 'machinery,' namely achieving energy conversion or material handling through moving parts. Heading 8460 specifically covers machine tools for deburring, sharpening, grinding, honing, lapping, polishing or otherwise finishing metals, sintered metal carbides or cermets by means of grinding stones, abrasives or polishing products. This heading includes surface grinding machines, cylindrical grinding machines, internal grinding machines, centerless grinding machines, tool grinding machines, honing machines, lapping machines, polishing machines, etc. The core criterion is that the processing method is grinding or polishing, and the processed object is metal or cermet. The degree of CNC or automation does not affect classification under this heading, but attention must be paid to distinguishing it from cutting machine tools (8457-8462) and forging, stamping machine tools (8462). HS code 846031 is a six-digit subheading. The first two digits '84' represent Chapter 84, namely nuclear reactors, boilers, machinery and mechanical appliances and parts thereof, covering all non-electrical mechanical power equipment. Digits 3-4 '60' represent heading 8460, namely machine tools for grinding, lapping, polishing, etc. of metals or cermets by means of grinding stones, abrasives or polishing products. Digits 5-6 '31' represent subheading 8460.31, specifically CNC internal grinding machines. Among them, '3' indicates the subcategory of internal grinding machines, and '1' indicates numerical control (CNC). Therefore, the complete meaning of 846031 is: CNC internal grinding machine, i.e., an internal grinding machine tool controlled by a CNC system, used for machining workpiece inner bores, internal conical surfaces, etc. This commodity is classified under 846031 rather than other codes, primarily because its processing method is internal grinding and it adopts CNC control. If it were an external cylindrical grinding machine, it should be classified under 8460.21 (CNC external cylindrical grinding machines); if it were a centerless grinding machine, it would be classified under 8460.12 (CNC centerless grinding machines). If it were a non-CNC internal grinding machine, it should be classified under 8460.29 (other internal grinding machines). In addition, if the machine tool is mainly used for gear processing, it may be classified under 8461; if it is laser processing, it is classified under 8456. Therefore, the determination of 846031 requires simultaneously satisfying three conditions: 'internal grinding,' 'CNC,' and 'metal processing.'

The core criteria for classification are: 1) whether the processing method is grinding (using grinding stones, abrasives or polishing products); 2) whether the processed object is metal or cermet; 3) whether the grinding type is internal grinding (machining workpiece inner bores); 4) whether CNC control is adopted. If all four points above are satisfied, it is classified under 846031. If the processing method is honing or lapping, it should be classified under 846040; if it is external grinding, under 846021; if it is non-CNC, under 846029. In addition, attention must be paid to the difference from 8461 (cutting machine tools): grinding machines remove material with abrasives, while cutting machine tools remove material with cutting tools. 846029 Other internal grinding machines: Non-CNC internal grinding machines, i.e., internal grinding machines not equipped with a CNC system, are classified under 846029. The only difference from 846031 is whether it is CNC. 846021 CNC external cylindrical grinding machines: Processes the external cylindrical surface of the workpiece, not the inner bore. If the machine tool has both internal and external grinding functions, it should be classified according to the main function or the principle of inseparable complete sets of equipment. 846040 Honing or lapping machines: Honing uses a honing head for precision machining of holes, and lapping uses abrasives; both differ in principle from grinding. 846040 includes CNC honing machines, but they are not grinding machines. 846012 CNC surface grinding machines: Processes flat surfaces, not inner bores. If the machine tool is an internal grinding machine but can also perform surface grinding, it is still classified under the internal grinding machine subheading according to the main function. 845710 Machining centers: Machining centers have automatic tool changing functions and can perform milling, drilling and other multiple operations, while internal grinding machines are dedicated to grinding. If the machine tool is mainly for grinding but has a tool magazine, it may still be classified under 846031. Is material removal performed using abrasives or grinding stones? Is the processed object metal or cermet? Is it specifically used for machining inner bores (internal grinding)? Is it equipped with a CNC system? Is it confused with honing, lapping, or cutting machine tools?

How do I look up the HS code for a CNC internal grinding machine? First confirm that the machine tool is for grinding, processes metal inner bores, and adopts CNC control. Then consult Chapter 84 of the Import and Export Tariff, find heading 8460, and select 8460.31 according to the subheading structure. You may also use the General Administration of Customs' classification decisions or advance classification services, providing machine tool technical parameters to obtain the accurate code. What is the difference in HS codes between CNC internal grinding machines and CNC external cylindrical grinding machines? CNC internal grinding machines are classified under 846031, and CNC external cylindrical grinding machines under 846021. The difference lies in the processing object: internal grinding machines process workpiece inner bores, while external cylindrical grinding machines process workpiece outer surfaces. If the machine tool has both internal and external grinding functions, it must be determined according to the main function or whether it can be separated, usually classified by main use. Which code should non-CNC internal grinding machines be classified under? Non-CNC internal grinding machines are classified under 846029 (other internal grinding machines). This subheading covers all internal grinding machines not equipped with a CNC system, including manual, semi-automatic, or digital display types. When classifying, proof of the machine tool's control method must be provided, such as the absence of a CNC controller. How are internal grinding machines and honing machines distinguished in classification? Internal grinding machines use grinding wheels or grinding heads for grinding and are classified under 8460.31 or 8460.29; honing machines use honing heads for low-speed precision machining and are classified under 8460.40. The two have different processing principles; honing removes less allowance and achieves higher surface quality. If the machine tool has both grinding and honing functions, it is classified according to the main function. What are common errors in the declaration elements of CNC internal grinding machines? Common errors include: not indicating the CNC system brand and model, filling in the processing object as a specific part rather than material, confusing internal grinding with honing, and ignoring brand type declaration. These errors may lead to incorrect classification or failure to pass customs review. It is recommended to declare strictly in accordance with the specifications. What regulatory documents are required for importing CNC internal grinding machines? According to customs regulations, importing CNC internal grinding machines usually requires an automatic import license (O certificate) and an inbound goods customs clearance form (if inspection and quarantine are required). The specific regulatory conditions depend on the machine tool's specifications, use, and country of origin. It is recommended to check the latest Customs Regulatory Conditions or consult a customs broker. How do I look up the tax rate for CNC internal grinding machines? Tax rates are adjusted according to national policies and can be checked through the General Administration of Customs website, China International Trade Single Window, or the Import and Export Tariff. Usually, after determining the code, check the most-favored-nation rate, general rate, value-added tax, and consumption tax. It is recommended to use the tax rate at the time of actual declaration. If a CNC internal grinding machine has an automatic loading and unloading device, does it affect classification? The automatic loading and unloading device is auxiliary equipment. If it forms a complete set of equipment with the grinding machine, it is still classified as a grinding machine. However, if the loading and unloading device is declared separately, it must be classified separately. According to the General Rules for Classification, complete sets of equipment are classified according to the main function, so it does not affect the determination of 846031.