# Mechatronics Questions and Answers – CNC Machines Basics

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This set of Mechatronics Multiple Choice Questions & Answers (MCQs) focuses on “CNC Machines Basics”.

1. What is the full form of CNC?
a) Computer numerical control
b) Computer numbercontrol
c) Computer network control
d) Computer numberscount

Explanation: Computer numerical control is the full form of CNC. If we provide software-based numerical control then it is called as computer numerical control. The other three options are not the perfect choice for the full form of CNC.

2. What does CNC machine use to control motion and speed?
a) Numerical
b) Programs, as well as computer keyboard, Graphical user interface
c) Feedback system
d) GUI

Explanation: CNC machine uses the program to control motion and speed. The feedback system is used to record data from the sensor and compare it with input data. The graphical user interface provides a facility to understand the position of the tool according to the input program.

3. The function of the feedback system is to record the data from the sensor and compare it with output data.
a) True
b) False

Explanation: Feedback system is to record the data from the sensor and compare it with input data. If there is an error found in the system, then it is controlled by sending new signals towards the driver.

4. What is the function of the GUI (Graphical user interface)?
a) To control motion and speed
b) Converts program into the action of the driver
c) To record the data from the sensor
d) To understand the position of the tool according to the input program

Explanation: To understand the position of the tool according to the input program is the function of GUI. CNC programs are used to control motion and speed. Machine control unit converts the program into the action of the driver. The feedback system is to record the data from the sensor and compare it with input data.

5. The punch tape reader in a CNC machine is ____
a) feedback system
b) input device
c) program
d) driving system

Explanation: The punch tape reader in a CNC machine is an input device. Magnetic tape, as well as computer keyboard, can be used in CNC as an input device. The feedback system is to record the data from the sensor and compare it with input data. CNC machine uses the program to control motion and speed.

6. Machine control unit implements interpolation commands to generate axial motion commands.
a) True
b) False

Explanation: Machine control unit implements interpolation commands to generate axial motion commands. It reads the code provided and decodes the instruction.

7. What is the function of the driving system in CNC?
a) Auxiliary control functions such as coolant
b) Speed and position control
c) Consist of amplifier circuits, driving motors and ball lead screw
d) To understand the position of the tool according to the input program

Explanation: Driving system consists of amplifier circuits, driving motors and ball lead screw. These are used to actuate the driving motors. Speed and position control is provided by machine tools. To understand the position of the tool according to the input program is the function of GUI.

8. Sensors used in measurement systems are ____
a) speed and position sensor
b) consist of amplifier circuits, driving motors and ball lead screw
c) numerical control sensors
d) measurement sensors

Explanation: Sensors used in measurement systems are speed and position sensors. The driving system consists of amplifier circuits, driving motors and ball lead screw. Numerical control sensors and Measurement sensors are not used in CNC devices.

9. Speed and Position in CNC can be controlled using _____
a) slide table and spindle
b) machine code unit
c) feedback system
d) graphic user interface

Explanation: Speed and position are controlled by using a sliding table and a spindle. X and Y directions are controlled by the machine table. The z-direction is controlled by spindle speed control. In the other options, The Machine control unit implements interpolation commands to generate axial motion commands. The feedback system is to record the data from the sensor and compare it with input data. To understand the position of the tool according to the input program, is the function of Graphic user interface.

10. In the block diagram of the CNC machine, data processing and control loop are a part of ____
a) speed and position sensor
b) feedback system
c) machine control unit
d) input device

Explanation: In the block diagram of the CNC machine, data processing and control loop are a part of the Machine control unit. Machine control unit implements interpolation commands to generate axial motion commands. The feedback system is to record the data from the sensor and compare it with input data. Speed and position are controlled by using a sliding table and a spindle. The punch tape reader in a CNC machine is an input device. Magnetic tape, as well as computer keyboard, can be used in CNC as an input device.

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