Lathe kinematics: When a single-point tool moves parallel to the lathe axis during turning, this motion is termed as which feed?

Introduction / Context:
On a lathe, the feed direction determines the surface generated. Understanding the nomenclature of feeds helps in selecting the proper motion for operations like straight turning, facing, and taper turning. The question asks you to identify the term used when the tool advances parallel to the spindle (work) axis.

Given Data / Assumptions:

• Conventional engine lathe with carriage and cross-slide.
• Single-point turning tool in a standard turning operation.
• No taper attachment engaged.

Concept / Approach:
Lathe feeds are classified primarily as longitudinal (parallel to spindle axis) and cross (radially toward/away from the axis). Longitudinal feed machines a cylindrical surface; cross feed produces facing cuts or changes in diameter. Angular or compound feeds combine motions to generate tapers or profiles.

Step-by-Step Solution:

Verification / Alternative check:
On the carriage, engaging the feed rod with the half-nuts and moving the saddle along the bed provides longitudinal feed; micrometer dials confirm axial travel, not radial.

Why Other Options Are Wrong:

• Cross feed: radial motion, used for facing and diameter adjustments.
• Angular/compound feed: combination of slides to produce tapers; not strictly parallel to the axis.
• Taper feed: informal term; actual mechanism is compound or taper attachment.

Common Pitfalls:
Confusing carriage (longitudinal) movement with cross-slide movement; always visualize the axis of the work to determine the feed designation.

Final Answer:
longitudinal feed