Single-point tool geometry terminology In metal cutting terminology, the angle measured between the tool face (rake face) and the tool flank (relief face) at the cutting edge is known as what?

Introduction / Context:
Correct identification of tool angles is fundamental for setting up turning and shaping operations. Each angle serves a distinct purpose: chip flow (rake), avoidance of rubbing (clearance), and edge strength (lip). Misnaming these angles leads to incorrect grinding and poor tool performance.

Given Data / Assumptions:

• Standard single-point cutting tool (e.g., HSS or carbide) for turning.
• Angles are defined per conventional tool geometry systems.
• We are considering the local geometry at the primary cutting edge.

Concept / Approach:
The rake angle is the inclination of the tool face that guides chip flow. The clearance (relief) angle is provided on the flank to prevent rubbing against the machined surface. The lip angle is the included angle between the rake face and the flank at the very cutting edge. It represents edge wedge strength; larger lip angle tends to strengthen the edge but increases cutting forces.

Step-by-Step Solution:
Identify the two surfaces meeting at the cutting edge: the rake face and the flank.The angle between these two surfaces is defined as the lip angle.Therefore, the term that fits the description is “lip angle.”

Verification / Alternative check:
Tool grinding charts list lip angle = 90° - rake angle - clearance angle (in a simplified 2D view), reinforcing that it is the included wedge angle at the cutting edge.

Why Other Options Are Wrong:
Rake angle is between rake face and a reference plane, not the flank. Clearance angle is between flank and machined surface (or a reference plane). Point angle typically refers to the included angle at a drill point or nose angle in lathe tools, not specifically the rake–flank included angle. Inclination angle is a separate 3D feature of tool orientation.

Common Pitfalls:
Assuming “point angle” is universal for all tools; it is specific to drills or tool nose context. Always check the surfaces defining the angle.

Final Answer:
Lip angle