Question:
A through hole of 10 mm diameter is to be drilled in a mild steel plate of 30 mm thickness. The selected spindle speed and feed for drilling hole are 600 revolutions per minute (RPM) and 0.3 mm/rev, respectively. Take initial approach and breakthrough distances as 3 mm each. The total time (in minute) for drilling one hole is ............. (Rounded off to two decimal places)
A through hole of 10 mm diameter is to be drilled in a mild steel plate of 30 mm thickness. The selected spindle speed and feed for drilling hole are 600 revolutions per minute (RPM) and 0.3 mm/rev, respectively. Take initial approach and breakthrough distances as 3 mm each. The total time (in minute) for drilling one hole is ............. (Rounded off to two decimal places)
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When calculating drilling time, consider both the feed rate and the spindle speed, and ensure you include the approach and breakthrough distances in your total distance calculation.
Updated On: Mar 12, 2026
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Correct Answer: 0.19
Solution and Explanation
To calculate the total time for drilling a hole, we use the formula:
\[
{Total time} = \frac{{Total distance}}{{Feed rate}} \times \frac{1}{{Spindle speed}},
\]
where:
- The total distance is the sum of the approach distance, breakthrough distance, and hole depth (30 mm).
- The feed rate is 0.3 mm/rev.
- The spindle speed is 600 RPM.
The total distance to be drilled is: \[ {Total distance} = 3 + 3 + 30 = 36 \, {mm}. \] Now, the total time is: \[ {Total time} = \frac{36}{0.3} \times \frac{1}{600} = \frac{120}{600} = 0.2 \, {minutes}. \] Thus, the total time for drilling the hole is approximately 0.20 minutes.
- The total distance is the sum of the approach distance, breakthrough distance, and hole depth (30 mm).
- The feed rate is 0.3 mm/rev.
- The spindle speed is 600 RPM.
The total distance to be drilled is: \[ {Total distance} = 3 + 3 + 30 = 36 \, {mm}. \] Now, the total time is: \[ {Total time} = \frac{36}{0.3} \times \frac{1}{600} = \frac{120}{600} = 0.2 \, {minutes}. \] Thus, the total time for drilling the hole is approximately 0.20 minutes.
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