This set of CNC Multiple Choice Questions & Answers (MCQs) focuses on “Computer Numerical Control Basics”.
1. The machine control unit in modern CNC comprises which of the following types of computers?
a) Minicomputer
b) Supercomputer
c) Microcomputer
d) Mainframe computer
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Explanation: Modern Computer Numerical Control uses a dedicated microcomputer. Mainframe computers are used for high storage and data processing. Minicomputers are medium-range computers. Supercomputers are used for fields that require immense computation like weather forecasting, scientific research, etc.
2. The machine control unit in CNC machines consists of which of the following components?
a) I/O Interface
b) Scanners
c) Plotters
d) Processing equipment
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Explanation: The machine control unit in CNC comprises Central Processing Unit, memory, I/O interface, controls for machine tool axes & spindle speed, and sequence controls for other machine tool functions. A system bus connects these subsystems for communication.
3. The central processing unit in CNC consists of which of the following parts?
a) Read Only Memory
b) Arithmetic Logic Unit
c) Secondary memory
d) Operating System Unit
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Explanation: Arithmetic Logic Unit performs various calculations, counting, and logical functions. Other parts of a CPU are the control section and immediate access memory. The control section retrieves data from memory and generates signals to activate other components in the machine control unit.
4. Operating System is stored in which memory?
a) Secondary memory
b) Random Access Memory
c) Immediate Access Memory
d) Read Only Memory
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Explanation: Operating System software is stored in the Read-Only Memory. Numerical Control part programs are stored in Random Access memory to perform operations on the current job and can be edited for a new job.
5. Which of the following is not a CNC software?
a) Machine sequencing software
b) Operating system
c) Machine interface software
d) Application software
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Explanation: Three types of software are used in the CNC system. These are operating system software, machine interface software, and application software. Application software consists of NC part programs for different operations.
6. Which of the following software interprets an NC part program?
a) Application software
b) Machine interface software
c) Operating system
d) Machine sequencing system
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Explanation: Operating system software interprets part programs and generates control signals to drive machine tool axes. The editor, control program, and executive program are parts of operating system software.
7. ______ allows the user to input and edit part programs.
a) Control program
b) Executive program
c) Machine interface program
d) Editor
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Explanation: Machine operator can input and edit a part program through the editor. The executive program manages the execution of Computer Numerical Control software and input-output operations of the machine control unit.
8. ________ operates the communication link between CPU and processing equipment.
a) Machine interface software
b) Operating system
c) Control program
d) Application software
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Explanation: The machine interface software operates the communication link between CPU and processing equipment to carry out CNC auxiliary functions. Control program decodes part program, perform interpolation, and produce coordinate control signals for each axis.
9. In CNC, a part program can be edited while it resides in machine control unit memory.
a) True
b) False
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Explanation: Earlier, in Numerical Control machines, the part program cannot be edited at the machine site. It has to be replaced by a new program. In Computer Numerical Control, it is possible to edit the part program at the machine site.
10. Which of the following features of modern CNC is an advantage over early Numerical Control machines?
a) Reprogramming ability
b) Capability to deal with product variety
c) Adaptive control
d) Lesser human assistance need
View Answer
Explanation: In modern CNC, the machine control unit can measure and analyze variables like tool-tip temperature, spindle speed, etc. It can adjust processing parameters like cutting speed, feed rate, etc. to maximum performance.
Sanfoundry Global Education & Learning Series – CNC.
To practice all areas of CNC, here is complete set of Multiple Choice Questions and Answers.
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