Principal function test for machine classification: special purpose carburettor machine fell under the specific heading, not the residuary entry.

Classification of the imported special purpose machine turned on its principal function: it plugged holes in carburettor bodies with lead shots, while cutting the extruded portion and checking airtightness were merely incidental. Applying the relevant section and chapter notes, the machine was treated as a machine tool working on metal under Heading 84.45/48, and the residuary Heading 84.59 could not apply where the specific heading covered the goods. The assessee's classification was therefore accepted.

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Issues: Whether the imported special purpose complex machine was classifiable under Heading 84.45/48 as a machine tool working on metal or under the residuary Heading 84.59 as a machine having an individual function not falling within any other heading.

Analysis: The decisive question was the true nature of the machine's function. The machine plugged holes in carburettor bodies with lead shots, and the cutting of the extruded portion and checking of airtightness were incidental to that principal function. On the evidence and functional description, the machine did not merely treat metal in a way that would exclude it from Heading 84.45/48. The classification had to be determined by the principal function under the relevant section and chapter notes, and once the machine was found to be a machine tool working on metal, the residuary heading could not apply.

Conclusion: The machine was classifiable under Heading 84.45/48 and not under Heading 84.59, and the assessee's classification was accepted.

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