Two mark questions and answers

TWO MARK QUESTIONS AND ANSWERS

1. What is the difference between absolute and incremental programming?

2. List the methods of creating part programming.

(i) Manual part programming.

(ii) Computer-assisted part programming (CAD/CAM based programming, system).

(iii) Manual data input

(iv) NC programming using CAD/CAM

(v) Computer automated part programming.

3. Write the disadvantages of manual part programming.

 [Anna Univ. Apr'18]

(i) Time required is more to actually develop a fully functioning CNC program such as manual calculations, verifications and related activities.

(ii) There is a chance of large percentage of errors, a lack of tool path verification and difficulty in making changes in a part program.

4. What is NC part programming?

[Anna Univ. Nov'19]

NC part programming is an advanced form of computer-assisted part programming in which an interactive graphics system equipped with NC programming software is used to facilitate the part programming task.

5. What are the data essentially needed to prepare a part program?

1. Job Dimension/workpiece

2. Work holding (damping, chucking)

3. Feed/cutting speed

4. Finished dimension with tolerance

5. Sequence of operation

6. Types of tools

7. Mounting of tools.

6. What are G-codes and M-codes?

[Anna Univ. Nov’17]

G-codes are preparatory function codes which prepare the machine or tool for different modes of movement such as positioning, contouring, thread cutting etc.

E.g. G00 - Point to point positioning

G01 - Linear interpolation.

M-codes are miscellaneous function codes which denote the auxiliary or switching information coolant on/off, spindle speed etc.

E.g. M00 - Pregame stop

M01 - Optional stop.

7. State the functions of the following G and M codes.

[Anna Univ. May'16]

G00 means Point to point positioning

G03 means Circular interpolation, anticlockwise

M06 means Tool change

M03 means Spindle clockwise.

8. What are the important steps to be followed while preparing part program?

1. Fixation of coordinate system

2. Reference of G and M codes

3. Dimensions of work and tools

4. Locating the fixture and machine table

5. Speed and feed according to the work and tool material.

9. What are the types of interpolations used in CNC systems?

1. Linear interpolation

2. Circular interpolation

3. Helical interpolation

4. Cubic/Parabolic interpolation.

10. What is meant by MACRO?

Macros are blocks of code that use any of the logical features such as variables, decision structures, or functions. It provides the user with some flexibility and automation through the use of variables, loops and decision structures. It can be used where certain motion sequences would be repeated several times within a program.

11. Define subroutine.

[Anna Univ. May'13]

If the same machining operation which was carried out already is to be performed at many different positions on the workpiece, it can be executed by means of a program called subroutines.

12. What is the function of a subroutine in CNC part programming? 

[Anna Univ. June'12]

(1) To perform at many different positions on the workpiece

(2) To perform a specific repetitive machining task

(3) To develop individual subroutines

(4) To debug the program.

13. What is a Canned cycle?

[Anna Univ. May'10 & May'14]

A Canned cycle is a combination of machine moves that performs anyone particular machining function such as drilling, turning, milling, boring, tapping etc.

14. What is meant by APT program?

 [Anna Univ. Dec'10]

APT program is used to command the cutting tool through its sequence of machining process. APT is also used to calculate the cutter positions. APT is a three dimensional system controlling up to five axes including rotational co-ordinates.

15. Write down the types of statements in APT language.

[Anna Univ. Dec'05]

1. Geometric statements

2. Motion statements

3. Postprocessor statements

4. Special control or Auxiliary statements.

16. What is 'Adaptive control”?

 [Anna Univ. May'14 & May'15]

The automatic monitoring and adjustment of machining conditions in response to variations in the operation performance is called adaptive control.