Machining fundamentals – what is threading? Identify the process that correctly defines the threading operation on a lathe or similar machine.

Introduction / Context:
Threading is a core turning operation used to produce fastening features. Confusing threading with related hole-finishing operations (reaming, counterboring) leads to incorrect process planning and tool selection.

Given Data / Assumptions:

• Conventional single-point threading on a lathe is considered.
• External screw threads on shafts, studs, or bolts.
• Standard feeds synchronized with spindle via a leadscrew/gearbox.

Concept / Approach:
External threading removes material in a helical path to form crests, roots, and flanks according to thread standards (e.g., metric, unified). The tool follows a lead equal to pitch per revolution, generating the helix.

Step-by-Step Solution:

Verification / Alternative check:
Measurement with thread pitch gauge and thread micrometer confirms the helix parameters match the target standard.

Why Other Options Are Wrong:

• Smoothing/squaring a hole mouth describes counterboring/chamfering, not threading.
• Sizing/finishing a hole is reaming.
• Removing metal along a hollow tool circumference is trepanning or core drilling.
• Press fitting is an assembly method, unrelated to thread cutting.

Common Pitfalls:
Mixing tapping (internal threading) with reaming; assuming multi-point dies are mandatory—single-point tools are common for flexible thread generation.

Final Answer:
Cutting helical grooves on the external cylindrical surface