Direction: Blind hole 10 mm diameter, 50 mm deep are being drilled in steel block, drilling spindle speed is 600 rpm, feed 0.2 mm/rev, point angle of drill is 120.
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Machining time (in min) per hole will be
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- 0.08
- 0.31
- 0.44
- 0.86
Correct Option: C
D = 10 mm Plate thickness = 50 mm N= 600 rpm feed = 0.2 mm/rev point Angle = 2∝ = 120°
Approach = 0.3D = 0.3 × 10 = 3mm
L = 3 + 50 = 53 mm
| Time/ hole = | = | = 0.442 min | ||
| fN | 0.2 × 600 |
