Classification depends on the machine's principal function. If the machine is designed and marketed primarily as a drilling machine that incorporates a tapping cycle, it likely belongs under the drilling-machine subheadings (845929 or 845921). If tapping is the primary operation and drilling is incidental or preparatory, classification under 845970 is more appropriate. CBP's essential character analysis and the machine's commercial documentation — including the manufacturer's product description and intended use — are the key inputs for resolving this question.

Threading machines typically cut external threads on rods, pipes, or bolts using dies or single-point tools, while tapping machines cut internal threads in pre-drilled holes using taps. Both operations are covered within the same HTS subheading (845970), so the distinction does not create a separate classification issue at the 6-digit level. However, importers should accurately describe the machine type in entry documentation to support any post-entry audit or ruling request.