# Machine Tools Questions and Answers – Classification of Drilling Machine : According to Length to Diameter Ratio and Shank Type

This set of Machine Tools and Machining Questions & Answers for entrance exams focuses on “Classification of Drilling Machine : According to Length to Diameter Ratio and Shank Type”.

1. If l/d ratio is too large, then drill becomes_______
a) weak
b) strong
c) very sharp
d) none of the mentioned

Explanation: The large l/d ratio weaken the drill. If we have very long drill with small diameter then it can’t perform drilling operation more accurately.

2. If l/d ratio is too short, then chip removal will be difficult.
a) true
b) false

Explanation: Chip removal will be difficult if this ratio is too short. Short l/d ratio weakens the drilling and reduce the performance. So the chip removal will be difficult.

3. Long drills are used for deep holes.
a) true
b) false

Explanation: As per the definition of long drill. Long drills has high l/d ration. So it can make high deeply holes.

4. For general purpose, l/d ratio should be_____
a) 5 to 10
b) 10 to 20
c) more than 20
d) none of the mentioned

Explanation: For general purpose, the ratio should be 5 to 10. The drills containing these ratio generally used in ordinary performances.

5. Which of the following can also be termed as center drill?
a) general drill
b) short drill
c) long drill
d) none of the mentioned

Explanation: Short drill can also be termed as centerr drill.

6. For long drills, l/d ratio should be more then 25.
a) true
b) false

Explanation: For long drills, this ratio should be more than 25. For general purpose it should have ratio of 5 to 10.

7. For small drill, l/d ratio should be 8 to 10.
a) true
b) false

Explanation: This is false. For small drill, l/d ratio should be 2 or 3.

8. According to the shank type, drill can be classified as______
a) straight shank
b) taper shank
c) both taper shank and straight shank
d) none of the mentioned

Explanation: Both taper shank and straight shank are the type of shank drill. Brace shank, straight shank, hex shank etc. are the type of shanks.

9. In ______ type, drill is held in spindle directly.
a) straight shank
b) taper shank
c) can’t say anything
d) none of the mentioned

Explanation: In taper type, drill is held in spindle directly. Taper shank drill is like a general purpose drill.

10. In _______ type, drill is held in chuck.
a) straight shank
b) taper shank
c) can’t say anything
d) none of the mentioned

Explanation: In straight type, drill is held in chuck. It is also known as reduced shank or blacksmith’s drill.

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