Free CNC Machine MCQ Question and Answers — Questions and Answers
Question 1: The tool is moved with the GOO command at
- Feed rate while machining
- Rapid traverse while machining
- Feed rate without machining
- Rapid traverse without machining (Correct answer)
Correct answer: Rapid traverse without machining
The G00 (G-zero-zero) command in CNC programming instructs the machine to move the tool at its maximum possible speed, known as rapid traverse. This command is exclusively used for non-cutting movements, such as quickly positioning the tool to a new starting point or retracting it from the workpiece. It prioritizes speed over precision and is never used when the tool is engaged in cutting material.
Question 2: The most widespread use of a CNC machine is in the field of
- non conventional machining
- small lot and batch production (Correct answer)
- mask production
- none of the above
Correct answer: small lot and batch production
CNC machines excel in small lot and batch production due to their exceptional flexibility and rapid setup capabilities. They can be quickly reprogrammed to produce different parts with varying geometries without extensive retooling, making them ideal for manufacturing a diverse range of components in moderate quantities. This adaptability allows companies to efficiently respond to changing market demands and reduce lead times compared to traditional machining methods.
Question 3: CNC machines cannot be used in
- Lathe
- Drilling machine
- Milling machine
- none of the above (Correct answer)
Correct answer: none of the above
CNC technology is highly versatile and has been successfully integrated into virtually all types of machine tools across the manufacturing industry. Lathes, drilling machines, and milling machines are among the most common applications for CNC control, enabling automated, precise, and complex machining operations. Therefore, it is incorrect to state that CNC machines cannot be used in any of these, as they are widely employed in all listed categories.
Question 4: In spindle motors for CNC machine tools, the is constant.
- Current
- Torque
- Speed
- Power (Correct answer)
Correct answer: Power
In CNC spindle motors, especially at higher speeds, the power output is typically constant. While torque is constant at lower speeds, as the speed increases beyond a certain point (base speed), the motor enters a constant power region where torque decreases proportionally with increasing speed. This constant power characteristic allows the spindle to maintain high material removal rates across a wide range of cutting speeds.
Question 5: An automated CNC mailer would have
- Point-to-point closed loop control only
- Countering control (Correct answer)
- Point-to-point open loop control only
- none of the above
Correct answer: Countering control
An automated CNC machine, particularly one capable of complex machining operations, requires contouring control. Contouring control allows the machine to move multiple axes simultaneously and in a coordinated manner to generate intricate curves and surfaces. This is essential for producing complex shapes and profiles, unlike point-to-point control which only moves to specific coordinates without controlled path generation between them.
Question 6: The main benefit of CNC machining over traditional machining is as follows:
- feedback control
- flexibility (Correct answer)
- ability to employ hugher cutting speeds, feeds and depth of cut
- none of the above
Correct answer: flexibility
While feedback control and the ability to employ higher cutting parameters are significant advantages, the main benefit of CNC machining over traditional methods is its exceptional flexibility. CNC machines can be easily reprogrammed to produce a wide variety of parts with different geometries and specifications, often with minimal setup changes. This adaptability makes them highly efficient for producing small to medium batches and responding quickly to design changes or diverse production needs.
Question 7: In the event that a machine has CNC control,
- Control is achieved by employment of alphanumeric data (Correct answer)
- The loading and unloading of the work piece ON and OFF the machine respectively is made automatic
- The dimension of the work piece are measured by sensors while cutting is going on
- The tool motion is guided by drum cams and disc cams
Correct answer: Control is achieved by employment of alphanumeric data
CNC (Computer Numerical Control) machines are fundamentally controlled by programs consisting of alphanumeric data, typically G-code and M-code. These codes define the tool path, feed rates, spindle speeds, and other machine functions. The machine's computer interprets this data to precisely control the movements of the machine axes and execute the machining operations, ensuring automated and accurate production.
