Cutting tool geometry statements: Identify the WRONG statement regarding rake angles, side cutting edge angle, and nose radius effects in turning.

Introduction / Context:
Tool geometry (rake, relief, approach angle, and nose radius) strongly influences chip formation, forces, temperature, and surface finish. Some trends are well known: insufficient rake increases rubbing, and larger nose radii often improve tool life up to a limit. This question asks you to pick the incorrect statement based on these principles.

Given Data / Assumptions:

• Single-point turning tool on steel.
• Normal feeds/depths of cut; machine rigidity is adequate.
• Continuous cutting without severe interruption.

Concept / Approach:
Side rake reduces shear deformation and cutting force but thins the edge as it increases, risking chipping at extremes. Very small rake raises ploughing and wear. The side cutting edge angle influences chip width and load distribution; too small an angle can focus load and hamper chip flow. Nose radius strengthens the tip, improves finish, and often prolongs life unless chatter or high radial forces occur from excessive radius.

Step-by-Step Solution:

Verification / Alternative check:
Handbooks recommend larger nose radii for roughing (within rigidity limits) precisely to enhance edge strength and distribute heat; finishing uses small to moderate radii for surface quality control.

Why Other Options Are Wrong:

• (a) Accurate: excessive side rake can weaken the edge.
• (b) Accurate: low rake increases rubbing and wear.
• (c) Overly small approach angles can reduce life; the claim that “less than 15° increases life” is not generally true, but among the choices, (d) is the clearly incorrect engineering trend.
• (e) Reasonable and commonly recommended.

Common Pitfalls:
Assuming “more is better” for any angle; ignoring machine rigidity and chatter when selecting nose radius; failing to balance finish requirements with edge strength.

Final Answer:
Increasing the nose radius decreases tool life.