GATE 2019 ME (ME1) – Question 62
A sharp ASA turning tool has side and end cutting-edge angles 45° and 10°. Feed is 0.1 mm/rev. Find generated surface centre-line average roughness (μm), to one decimal place.
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Correct answer: 3.5 to 3.9
Explanation
The triangular feed-mark height is $h=f/(\cot45^\circ+\cot10^\circ)=0.014990$ mm. Average roughness is $R_a=h/4=0.0037474$ mm, or 3.7474 μm. Rounded to one decimal, **3.7 μm**.