1. What is NC machine?
2. What are the advantages of using NC machine over traditional machine tools?
3. What is "part program" used in CNC machine?
4. What is punched tape? What are the disadvantages of using "punched tapes" used in earlier
generations of NC machine tools?
A punched tape is a paper tape that is punched with an ordered list of program blocks. Each
perforation on the punched tape denotes a symbol of the program.
Disadvantage:
a. It is tedious to change the tape instructions, because, a fresh new tape has to be made
for every change.
b. Punched tapes had a limited life.
5. What is CNC (computer numerical control), dNC (direct numerical control), DNC (distributed
numerical control)? Specify the advantages of each over other.
The different NC processes and their advantages over one another are as follows:
a. CNC
.
b. dNC
c. DNC
6. What are the different components of NC machine tool?
7. What is MCU in NC and write down its function?
8. Clearly explain with figure point-to-point motion control and continuous path motion control
used in NC machines? Which is control system is generally used to perform machining on the
workpieces?
Continuous path motion control is generally used..
9. What is closed loop control system and open loop control system used in NC machine? What are
the differences between them? What are the motors used for each type?
10. What is adaptive control system?
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11. Write down the differences between incremental positioning and absolute positioning system
used in NC machine?
12. Which system of co-ordinate system is used in NC machine? Write down the directions of
positive X,Y,Z axis in case of lathe.
In NC Machine, right-handed XYZ coordinate system is used.
In case of Lathe machine, Z-axis is parallel to the spindle, X-axis is in the direction of tool
movement and the third axis is Y-axis.
13. Briefly explain about the different types of tape format: Fixed sequential format, Block-address
format, Tab-sequential format, Word address format:
14. What is ATC in CNC machine?
ATC stands for Automatic Tool Changer in a CNC machine. It is utilized to automatically change
the tool in a CNC machine.
15. Write down the functions of few G codes like G01, 002 003,004 etc.
16. N0100 G02 X9.000 Y8.000 I5.000 J2.000 F6.000 Explain each .term for this block of the part
program.
N0100: Sequence number of the Part program.
G02: Circular Interpolation Clockwise
X9.000 Y8.000: coordinates of end point of the circular arc to be (9.000, 8.000)
I5.000 J2.000: coordinates of end point of the circular arc to be (5.000, 2.000)
F6.000: Specifies the feed speed to be 6 ipr