CNC Lab Exam 1

The emergency button is the correct answer because it is specifically designed to stop the program immediately in case of an emergency. It serves as a safety measure to quickly halt any potentially dangerous or harmful actions or processes. The other options, such as the feedback system, display unit, and servo motor, do not have the same function or purpose as the emergency button in terms of stopping the program instantly in emergency situations.

The letter "F" in CNC programming is used to specify the feed function. Feed function refers to the rate at which the cutting tool moves along the workpiece during the machining process. It determines the speed at which the material is removed and the accuracy of the final product. By adjusting the feed rate, operators can control the cutting speed and optimize the machining process for different materials and cutting conditions.

In CNC milling, the three functional axes are X, Y, and Z. These axes represent the three directions in which the milling machine can move. The X-axis represents the horizontal movement from left to right, the Y-axis represents the vertical movement from front to back, and the Z-axis represents the vertical movement from top to bottom. These axes allow the milling machine to move and position the cutting tool accurately in order to create precise and complex shapes in the workpiece. Therefore, the statement "The three functional axes in CNC Milling are X, Y & Z" is true.

The statement "Feed function is specified by 'R' Value" is false. The feed function is not specified by the 'R' value.

The given statement is true. Part programs, which contain the instructions for a specific task, can be loaded into and unloaded from the memory of a system or stored on external storage devices such as floppy disks or USB flash drives. This allows for flexibility and ease of access when it comes to managing and executing part programs on a system.

The correct answer is (d) T. The tool function is specified by the letter "T".

The movement of the machine slide is carried out manually by pressing a specific jog button, either the "+" or the "-". This suggests that the machine slide does not move automatically but requires manual input from the operator. Therefore, the statement "True" accurately reflects this explanation.

In the G00 function, feed rate is not required to be specified. The G00 function is used for rapid positioning, where the machine moves at its maximum speed to quickly move to a new position without considering the feed rate.

The reaming operation is used for finishing a hole. Reaming is a metalworking process that involves enlarging and smoothing out a pre-existing hole to achieve a precise diameter and smooth surface finish. This is typically done after drilling or boring operations to achieve the desired size and surface quality for the final product.

The major difference between NC (Numerical Control) and CNC (Computer Numerical Control) machines is the level of flexibility and reliability they offer. NC machines are controlled by a set of instructions programmed on punched cards or tapes, while CNC machines are controlled by a computer. CNC machines provide greater flexibility as they can be easily reprogrammed and offer higher precision and reliability due to their computer-controlled systems. Therefore, the statement "Major difference between NC and CNC machine lies in the improved flexibility and reliability" is true.

The given correct answer is "False". The explanation for this answer is that the double semicolon ";;" does not indicate the start of a program. In most programming languages, the double semicolon is not a valid syntax and would result in a compilation or syntax error. The correct symbol to indicate the start of a program varies depending on the programming language, but it is typically a specific keyword or a specific function or method that is called to begin the program execution.

The given statement is false because the code used for the end of the program is not "M04". The code used for the end of the program can vary depending on the programming language being used.

The given statement is false. The code used for coolant Off is not M05.

Programming a CNC machine requires a combination of training, knowledge, and following the manual. Without proper training, one may not have the necessary skills to operate the machine safely and efficiently. Additionally, having knowledge about CNC programming principles and techniques is crucial to ensure accurate and precise machining. Lastly, referring to the machine's manual is essential to understand its specific features, functions, and operating procedures. Therefore, all three factors - training, knowledge, and the manual - are necessary to program a CNC machine effectively.

The preparatory function used for circular interpolation is G03. This function is used in CNC programming to create circular movements in a clockwise direction. It is commonly used in machining operations such as milling and turning to create curved features or contours. By specifying the center point, radius, and other parameters, the G03 command enables the machine to accurately follow the desired circular path.

The G28 code is used to move the machine to its home position. This is the reference point for the machine, where all other movements are based from. By using the G28 code, the machine can be easily reset to its starting position, ensuring accurate and consistent movements throughout the machining process.

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The correct answer is "a) mm/rev". The unit for feed is typically expressed as mm/rev, which stands for millimeters per revolution. This unit represents the distance that the cutting tool travels along the workpiece for each revolution of the spindle. It is commonly used in machining operations to specify the rate at which the cutting tool advances into the workpiece.

The correct answer is a) G00. G00 is the rapid traverse command in CNC programming. It is used to move the tool quickly along a straight line to save time. This command is commonly used when the tool needs to move to a new position without cutting or machining any material.

The correct answer is "a) Inch Input". This suggests that the G20 preparatory function is used for inch input.

The correct answer is "a) Compensation cancel". This indicates that G40 is used to cancel any compensation that may have been applied previously.

In a closed-loop system, feedback devices are used to monitor the output. This allows the system to continuously compare the desired output with the actual output and make adjustments accordingly. Without feedback devices, the system would not have the necessary information to make these adjustments, resulting in a less accurate and efficient system. Therefore, the statement that feedback devices do not monitor the output in a closed-loop system is false.

The reaming operation is used for finishing a hole. Reaming is a machining process that is used to enlarge and smooth out a previously drilled or bored hole to achieve a precise diameter and smooth surface finish. This process is typically done after drilling or boring to improve the accuracy and quality of the hole. Therefore, option c) "Finishing hole" is the correct answer.

The M code M98 stands for a sub program.

M07 is a code used in CNC machining to turn on the coolant system. Coolant is important in machining operations as it helps to lubricate and cool down the cutting tool, reducing friction and preventing overheating. This code is typically used at the beginning of a machining operation to ensure that the coolant system is activated and ready to provide the necessary cooling and lubrication throughout the process.

In CNC Lathe, the functional axes are X and Z. This means that the X-axis controls the movement of the cutting tool in the horizontal direction, while the Z-axis controls the movement of the cutting tool in the longitudinal direction. The Y-axis is not included as one of the functional axes in CNC Lathe. Therefore, option c) X & Z is the correct answer.

The correct answer is (a) G81. G81 is the G-code command used for drilling in CNC lathe machines. When this command is executed, the machine will perform a drilling operation at a specified location on the workpiece. This command is commonly used for creating holes in the workpiece during the machining process.

In Absolute programming, only one reference point is taken into consideration. This means that all positions and movements are measured and defined relative to this single reference point.

The movement of the machine slide is carried out automatically in AUTO mode. In Jog mode, the movement is controlled manually by the operator. In MDI (Manual Data Input) mode, the operator manually enters the commands for the machine to execute. Therefore, the correct answer is c) AUTO.

To save programming time and reduce errors, the method of using sub programs is employed. Sub programs are reusable code blocks that can be called multiple times within a program. By using sub programs, programmers can avoid writing the same code repeatedly, leading to time savings and reducing the chances of making errors. Sub programs also enhance code modularity and maintainability by dividing the program into smaller, manageable parts.