Topic: Manufacturing Engineering
The relationship of the shear angle is as per ('$\alpha$' is rake angle and '$\beta$' is friction angle)
- A. Ernst-Merchant theory
- B. Merchant's theory
- C. Stabler theory
- D. Lee and Shaffer theory
Answer: A. Ernst-Merchant theory
Explanation: According to the Ernst-Merchant theory (minimum energy criterion), the relationship for the shear angle $\phi$ is given by $2\phi + \beta - \alpha = \frac{\pi}{2}$ (or $90^{\circ}$). Lee and Shaffer theory is $\phi + \beta - \alpha = \frac{\pi}{4}$ (or $45^{\circ}$).