Mechanical Engineering - Production Engineering - Discussion

Discussion Forum : Production Engineering - Section 4 (Q.No. 12)
12.
The ratio between two consecutive spindle speeds for a six-speed drilling machine using drills of diameter 6.25 to 25 mm size and at a cutting velocity of 18 m/min is
1.02
1.32
1.66
1.82
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
12 comments Page 2 of 2.

Pravin said:   9 years ago
@Vishwas.

Why are you taken min/ max dia= 3. 14* 6.25/25?

Vishwas Patel said:   10 years ago
If n = no of spindle speeds.

The ratio between two consecutive spindle speeds is:

R = (Max rpm/min rpm)^1/(n-1).

Max rpm = (1000 * Cutting velocity)/Min diameter.

= (1000 * 18)/3.14 * 6. 25.

= 917.197.

Min rpm = (1000 * Cutting velocity)/Max diameter.

= (1000 * 18)/3.14 * 25 = 229.299.

Now ratio R = (917.197/229.299)^1/5.

= 1.32.


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