GATE 2020 ME (ME1) – Question 32
Sheet metal of stock hardness 250 HRC is sheared using a punch and die with 1 mm clearance. If stock hardness increases to 400 HRC, estimate the clearance (mm).
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Correct answer: 1 to 1.3
Explanation
Using the empirical clearance dependence on the square root of material strength/hardness, $c_2/c_1=\sqrt{400/250}$. Thus c₂=**1.26 mm**. The empirical model is approximate; the source key accepts 1.0–1.3 mm.