CNC Machinist Certification Practice
Questions with Explanations | Docsity
Mock Exam 2025
1. What does CNC stand for?
A. Computer Numeric Calculation
B. Computer Numerical Control
C. Controlled Numeric Computer
D. Calculated Numerical Code
Rationale: CNC stands for Computer Numerical Control,
referring to machines controlled by computer programs.
2. What is the purpose of a G-code in CNC programming?
A. Defines tool wear
B. Specifies motion and positioning commands
C. Measures part tolerance
D. Determines spindle speed only
Rationale: G-codes control motion, positioning, and
machine operations.
3. Which axis typically represents the spindle on a vertical milling
machine?
A. X-axis
B. Y-axis
C. Z-axis
D. C-axis
Rationale: On vertical mills, the Z-axis is aligned with
the spindle axis.
4. What does the G00 command do?
A. Rapid positioning
, B. Linear interpolation
C. Circular interpolation
D. Tool change
Rationale: G00 moves the tool rapidly between points
without cutting.
5. What is the function of G01?
A. Rapid traverse
B. Linear interpolation (feed motion)
C. Circular interpolation
D. Tool home
Rationale: G01 commands controlled feedrate
movement for cutting.
6. Which command returns the tool to machine home position?
A. G01
B. G28
C. G40
D. G90
Rationale: G28 moves the machine to its reference
home position.
7. What does M03 do in a CNC program?
A. Starts spindle clockwise
B. Starts spindle counterclockwise
C. Stops spindle
D. Turns coolant on
Rationale: M03 initiates clockwise spindle rotation.
8. What is the meaning of M05?
A. Start spindle
B. Stop spindle
C. Turn coolant off
, D. End of program
Rationale: M05 halts spindle rotation.
9. What does M30 signify?
A. Pause program
B. Start main spindle
C. End of program and rewind
D. Coolant on
Rationale: M30 marks the end of a program and resets it
to the beginning.
10. Which coordinate system uses G54?
A. Work coordinate system 1
B. Machine coordinate system
C. Tool length offset
D. Incremental system
Rationale: G54 defines the first work coordinate offset.
11. Which of the following commands cancels all tool radius
compensation?
A. G40
B. G41
C. G42
D. G43
Rationale: G40 cancels cutter compensation.
12. What does G41 indicate?
A. Cutter compensation left
B. Cutter compensation right
C. Cancel cutter comp
D. Tool length comp
Rationale: G41 compensates tool path to the left of the
program path.
Questions with Explanations | Docsity
Mock Exam 2025
1. What does CNC stand for?
A. Computer Numeric Calculation
B. Computer Numerical Control
C. Controlled Numeric Computer
D. Calculated Numerical Code
Rationale: CNC stands for Computer Numerical Control,
referring to machines controlled by computer programs.
2. What is the purpose of a G-code in CNC programming?
A. Defines tool wear
B. Specifies motion and positioning commands
C. Measures part tolerance
D. Determines spindle speed only
Rationale: G-codes control motion, positioning, and
machine operations.
3. Which axis typically represents the spindle on a vertical milling
machine?
A. X-axis
B. Y-axis
C. Z-axis
D. C-axis
Rationale: On vertical mills, the Z-axis is aligned with
the spindle axis.
4. What does the G00 command do?
A. Rapid positioning
, B. Linear interpolation
C. Circular interpolation
D. Tool change
Rationale: G00 moves the tool rapidly between points
without cutting.
5. What is the function of G01?
A. Rapid traverse
B. Linear interpolation (feed motion)
C. Circular interpolation
D. Tool home
Rationale: G01 commands controlled feedrate
movement for cutting.
6. Which command returns the tool to machine home position?
A. G01
B. G28
C. G40
D. G90
Rationale: G28 moves the machine to its reference
home position.
7. What does M03 do in a CNC program?
A. Starts spindle clockwise
B. Starts spindle counterclockwise
C. Stops spindle
D. Turns coolant on
Rationale: M03 initiates clockwise spindle rotation.
8. What is the meaning of M05?
A. Start spindle
B. Stop spindle
C. Turn coolant off
, D. End of program
Rationale: M05 halts spindle rotation.
9. What does M30 signify?
A. Pause program
B. Start main spindle
C. End of program and rewind
D. Coolant on
Rationale: M30 marks the end of a program and resets it
to the beginning.
10. Which coordinate system uses G54?
A. Work coordinate system 1
B. Machine coordinate system
C. Tool length offset
D. Incremental system
Rationale: G54 defines the first work coordinate offset.
11. Which of the following commands cancels all tool radius
compensation?
A. G40
B. G41
C. G42
D. G43
Rationale: G40 cancels cutter compensation.
12. What does G41 indicate?
A. Cutter compensation left
B. Cutter compensation right
C. Cancel cutter comp
D. Tool length comp
Rationale: G41 compensates tool path to the left of the
program path.
