This set of Machine Tools Multiple Choice Questions & Answers (MCQs) focuses on “Lathe : Centers-1”.
1. How many main type of centres are there in lathe (most commonly)?
a) 1
b) 2
c) 3
d) 4
View Answer
Explanation: Most commonly two types of centres are there in lathe : live and dead centres.
2. Which of the following is not the type of centre in lathe?
a) live centre
b) neutral centre
c) dead centre
d) none of the mentioned
View Answer
Explanation: Only live centre and dead centre are there in lathe. These two centres take up the thrust due to metal cutting and the entire load of the workpiece on small bearing surface.
3. In which type of lathe centre, the hard tip is wear resistant?
a) tipped centre
b) revolving centre
c) ordinary centre
d) half centre
View Answer
Explanation: In tipped centre, the hard tip is wear resistant. Wear resistant means they are not easily affected by friction or any other damage
4. Why lathe centres are made of very hard materials?
a) to resist deflection
b) to resist wear
c) to resist deflection and wear both
d) none of the mentioned
View Answer
Explanation: Lathe centres are made of very hard to resist these both things-deflection and wear. The dead centre is subjected to wear due to friction.
5. Which type of centre is particularly suitable for taper turning?
a) ball centre
b) female centre
c) half centre
d) none of the mentioned
View Answer
Explanation: Ball centre is particularly suitable for taper turning as per the definition of the ball centre. It has minimum wear and strain.
6. What is the included angle of centre for general purpose work?
a) 30
b) 45
c) 60
d) 75
View Answer
Explanation: The included angle is usually 60 for general purpose work. Also, the included angel for heavy work is 75.
7. The shanks of all the centres are machined to the Morse 0 to 3 tapers.
a) true
b) false
View Answer
Explanation: This is false. Generally, the shank of all the centres is machined to the Morse 0 to 6 tapers.
8. Lathe centers are mde up of very hard materials.
a) true
b) false
View Answer
Explanation: This is true. These lathe centers are made up of very hard materials as they have to resist entire load of the workpiece and thrust.
9. The shanks of all the centres are machined to the metric 2 to 4 standard taper.
a) true
b) false
View Answer
Explanation: This is false. Generally, the shank of all the centres are machined to the metric 4 to 6 standard taper.
10. Which of the following is the type of lathe centres?
a) ordinary centre
b) tipped centre
c) ball centre
d) all of the mentioned
View Answer
Explanation: These all are the types of lathe centres. Apart from ordinary centre, tipped centre and ball entre, some other type centres are also there like half centre, pipe centre, revolving centre, insert type centre, self driving centre, female centre and so on.
11. Only the small high-speed steel insert is replaced.
For which type of centre, above sentence is true?
a) ball centre
b) swivel V centre
c) ordinary centre
d) none of the mentioned
View Answer
Explanation: Non of the mentioned option is correct. Above sentence is true for insert-type centre.
12. Self-driving live centre can be used only for soft jobs.
a) true
b) false
View Answer
Explanation: Self-driving live centre can be used only for soft jobs and not for hardened jobs. It bis used while machining the entire length of the job in one setting.
13. Grooves cut along the diameter of the centre point provide for
good gripping of the job and for getting the drive, in self-driving live centre.
a) true
b) false
View Answer
Explanation: This is false. Grooves cut around the circumference of the centre point provide for good gripping of the job and for getting the drive.
14. Which type of centre is used to drill holes across the round job
by using a drill bit in the head-stock spindle?
a) swivel V centre
b) female centre
c) half centre
d) none of the mentioned
View Answer
Explanation: Swivel V centre is used to drill holes across the round job by using a drill bit in the head-stock spindle as per the definition of this centre. This centre is used to support a job in the V section.
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