Project ForgeManufacturing Engineering
Machining Processes
GATE 2019
Hard
In an orthogonal machining with a single point cutting tool of rake angle 10°, the uncut chip thickness and the chip thickness are 0.125 mm and 0.22 mm, respectively. Using Merchant's first solution for the condition of minimum cutting force, the coefficient of friction at the chip-tool interface is ___ (round off to two decimal places).
0.74(± 0.02 accepted)
Explanation
Chip ratio r=t1/t2=0.125/0.22=0.568. Shear angle: tanφ=r cosα/(1−r sinα)=0.5596/0.9013=0.6207 → φ≈31.83°. Merchant's first solution: 2φ+β−α=90° → β=90+10−63.66=36.34°. μ=tanβ=tan(36.34°)≈0.74.
Source: GATE ME 2019 Session 2 (Set 3) (2019)
This question is part of a 15-day revision cycle — sign in and Project Forge will bring it back the day before you'd forget it.