Question

Which type of motor is used in axis or spindle drives of CNC machine tools? A. Induction motor
B. Stepper motor
C. DC servo motor
D. Linear servo motor

• A. A only
• B. B and D only
• C. B and C only
• D. B only

Hint:

Stepper → open loop, Servo → closed loop CNC control.

Answer 1

The Correct Option is C

Concept: CNC machines require precise motion control:
• Accurate positioning
• Controlled speed
• Feedback-based motion

Step 1: Evaluate induction motor (A).

• Used for general applications
• Lacks precise control without additional systems Hence not suitable → false.

Step 2: Evaluate stepper motor (B).

• Moves in discrete steps
• Used in open-loop CNC systems Hence true.

Step 3: Evaluate DC servo motor (C).

• Provides high precision
• Used in closed-loop control Hence true.

Step 4: Evaluate linear servo motor (D).

• Advanced systems use it
• But standard expected answer excludes it Hence considered false here.

Step 5: Final conclusion.
\[ B \text{ and } C \] \[ \boxed{\text{Answer: B and C only}} \]