Discussion
If the cutting speed is 20 m/ min, what is the rotational speed required for a 20 mm drill bit?
Answer: B
The required speed is about 320 rpm.
Cutting speed \(v = \frac{\pi d N}{1000}\) with \(v\) in m/min and \(d\) in mm, so
\[ \begin{aligned} N &= \frac{1000\,v}{\pi d} = \frac{1000 \times 20}{3.14 \times 20} \\ &\approx 318\ \text{rpm} \end{aligned} \]
which rounds to 320 rpm. 400 rpm would suit a drill of about 16 mm and 160 rpm one of about 40 mm, so both use the wrong diameter; 120 rpm would need a drill of about 53 mm.
No comment is present. Be the first to comment.
Loading…
Post your comment
Please log in or register to post a comment.
Examination Categories
- SSC Exams
- Banking Exams
- Teaching Exams
- Civil Services Exams
- Railways Exams
- Engineering Recruitment Exams
- Defence Exams
- State Government Exams
- Police Exams
- Insurance Exams
- Nursing Exams
- Other Government Exams
- NRA CET
- PG Entrance Exams
- Campus Placement
- MBA Entrance Exams
- CUET and UG Entrance
- Judiciary Exams
- Regulatory Body Exams
- Software Development