Difficulty: Easy
Correct Answer: Direction of cutting velocity
Explanation:
Introduction / Context:
The shear angle is central in chip-formation mechanics. It appears in Merchant's analysis and affects chip thickness, cutting force, and heat generation.
Given Data / Assumptions:
Concept / Approach:
The shear angle φ is defined as the angle between the shear plane and the direction of cutting velocity. With chip thickness t_c, uncut chip thickness t_o, and rake angle α, the relationships include geometry and force models (e.g., Merchant's minimum energy criterion).
Step-by-Step Solution:
Verification / Alternative check:
Alternative equivalent definition uses 90° − φ as the angle between the shear plane and the work surface; hence choosing the work surface would be incorrect without that complement.
Why Other Options Are Wrong:
Work surface relates by complement (90° − φ), not φ itself. Tool rake face angle is α, not φ. Spindle axis and normal to work surface are unrelated reference directions for defining φ.
Common Pitfalls:
Interchanging φ with 90° − φ, leading to errors in chip-thickness ratio and force predictions.
Final Answer:
Direction of cutting velocity
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