General Procedures for Machining Parts by NC Milling Machine
CNC milling machine general operation steps
(1) The machining program of the workpiece should be prepared first before machining. If the machining program of the workpiece is long and complicated, it is best not to program on the machine, but to use the programming machine or computer programming, so as to avoid occupation of the machine, the short program should also be written on the program list.
(2) Starting up is generally to open the machine and then open the system. Some designs are interlocked, and the machine cannot display information on the CRT without power.
(3) Referencing point For machines with incremental control systems (using incremental position sensing elements), this step must first be performed to establish a movement reference for each coordinate of the machine.
(4) Calling the machining program According to the program's storage medium (paper tape or tape, disk), you can use a tape reader, cassette tape drive, programming machine or serial communication input. If it is a simple program, you can directly use the keyboard to enter on the CNC control panel. If the program is very simple and only processes one, the program is not saved. MDI can be used to input segments one by one and segment by segment. In addition, the workpiece origin, tool parameters, offset amount, and various compensation amounts used in the program must also be input before processing.
(5) Editing the program If you need to modify the program, you need to edit it. At this time, set the mode selection switch to the edit position and use the edit button to add, delete, and change. See the corresponding instructions for the editing method.
(6) Machine lock, run the program This step is to check the program. If there is an error, you will need to edit it again.
(7) Manually incremental movement of the upper workpiece and the alignment tool, continuous movement or moving the machine with a hand wheel. Set the starting point to the beginning of the program and benchmark the good tool.
(8) The start of coordinate feed for continuous machining is generally processed in memory. This method has a lower failure rate than the processing on the tape. The feed rate during machining can be adjusted with the feedrate override switch. During the machining, the feed hold button can be pressed to pause the feed motion, observe the machining situation or perform manual measurement. Press the cycle start button again to resume machining. In order to ensure that the program is correct, it should be reviewed again before processing. In the case of milling, for a flat curve workpiece, a pencil can be used instead of the workpiece contour on the paper, which is more intuitive. If the system has a tool path simulation function, it can be used to check the correctness of the program.
(9) Operation display The position of the table or tool, the program, and the state of the machine tool are displayed on each screen of the CRT to allow the operator to monitor the machining situation.
(10) After the program output processing is completed, if the program is saved, it can be left in the CNC memory. If the program is too long, you can output the program in the memory to an external device (such as a puncher). Save on a perforated tape (or tape, disk, etc.).
(11) Shutdown generally should first shut down the machine and then shut down the system.
(2) When starting up, first turn on the main power, then press the open button in the CNC power supply to rotate the emergency stop button clockwise. After all the functions of the milling machine have been detected (a row of red LEDs on the lower operation panel is turned off), press the machine button to reset the milling machine and be on standby.(3) During manual operation, it is important to always note that the Z axis must be in the lift position before moving in the X and Y directions. During the movement, you can't just look at the change of the coordinate position in the CRT screen, but watch the movement of the tool. After the tool moves into position, look at the CRT screen for fine adjustment.
(4) In the programming process, for beginners, try to use the G00 command as little as possible, especially in the X, Y, Z three-axis linkage, more attention should be paid. When the knife is emptied, the movement of the Z axis should be separated from the movement of the X and Y axes, that is, the knife is lifted more and less obliquely inserted. Sometimes, due to oblique insertion, the tool will hit the workpiece and the tool will be destroyed.
(5) When using a computer for serial communication, you need to: First open the milling machine, then open the computer; Turn off the computer first, then turn off the milling machine. Avoid milling machines in the process of switching, impacting the computer due to instantaneous changes in current.
(6) When using the DNC (transfer between computer and milling machine) function, pay attention to the memory capacity of the milling machine. Generally, the total number of bytes transferred from the computer to the milling machine should be less than 23kB. If the program is long, it must be processed by the computer while transmitting, but the block number must not exceed N9999. If the program segment exceeds 10,000, you can cancel the block number with the help of the program editing function in MASTERCAM.
(7) When the milling machine has an alarm, it is necessary to find the cause according to the alarm number and release the alarm in time. Do not shut down the device, otherwise it will still be in alarm state after booting.
Using the edge finder to set the knife, the detailed steps are as follows:
X, Y to the knife
1. Mount the workpiece on the machine table through the clamp. When clamping, the measurement position of the edge finder should be left on all four sides of the workpiece.
2, quickly move the workbench and the spindle, so that the edge finder probe is close to the left side of the workpiece;
3, use the fine adjustment operation, let the probe slowly touch the left side of the workpiece until the edge finder emits light, and record the X coordinate value in the machine coordinate system at this time, such as -310.300;
4. Raise the edge finder to the upper surface of the workpiece, and quickly move the table and the spindle so that the probe is close to the right side of the workpiece;
5, use the fine-tuning operation, let the probe slowly touch the left side of the workpiece until the edge-trigger emits light, and record the X coordinate value in the mechanical coordinate system at this time, such as -200.300;
6. If the diameter of the probe is 10mm, the length of the workpiece is -200.300-(-310.300)-10=100. According to this, the X coordinate value of the workpiece coordinate origin W in the machine coordinate system is -310.300+100/2+5= -255.300;
7. Similarly, the Y coordinate value of the workpiece coordinate system origin W in the machine coordinate system can be measured.
Z to the knife
1. Remove the edge finder and install the tool used for machining on the spindle;
2. Place the Z-axis setter (or the fixed height of the tool block, the same below) on the upper surface of the workpiece;
3. Move the spindle quickly so that the end face of the tool is close to the upper surface of the Z-axis setter;
4. Use the fine adjustment operation to make the end face of the tool slowly touch the upper surface of the Z axis setter until its pointer indicates zero position.
5, note the Z value in the machine coordinate system at this time, such as -250.800;
6. If the height of the Z-axis setter is 50mm, the Z coordinate of the workpiece coordinate system origin W in the machine coordinate system is -250.800-50-(30-20)=-310.800.
(3) Input the measured X, Y, and Z values into the machine workpiece coordinate system storage address (usually use the G54-G59 code to store the tool setting parameters).
matters needing attention
Pay attention to the following issues during the tool setting operation:
(1) Adopt the correct tool setting tool according to the processing requirements to control the tool setting error;
(2) During the tool setting process, the precision of the tool setting can be improved by changing the fine adjustment feed amount;
(3) Care must be taken when setting the knife, especially pay attention to the direction of movement to avoid the risk of collision;
(4) The tool setting data must be stored in the storage address corresponding to the program to prevent serious consequences due to the call error.
Second, the input and modification of the tool compensation value
The tool radius compensation value and the tool length compensation value are input to the storage location corresponding to the program according to the actual size and position of the tool.
It should be noted that the correctness of the compensated data, the correctness of the symbol and the correctness of the address where the data is located will threaten the processing, resulting in a collision risk or processing scrap.
(1) The machining program of the workpiece should be prepared first before machining. If the machining program of the workpiece is long and complicated, it is best not to program on the machine, but to use the programming machine or computer programming, so as to avoid occupation of the machine, the short program should also be written on the program list.
(2) Starting up is generally to open the machine and then open the system. Some designs are interlocked, and the machine cannot display information on the CRT without power.
(3) Referencing point For machines with incremental control systems (using incremental position sensing elements), this step must first be performed to establish a movement reference for each coordinate of the machine.
(4) Calling the machining program According to the program's storage medium (paper tape or tape, disk), you can use a tape reader, cassette tape drive, programming machine or serial communication input. If it is a simple program, you can directly use the keyboard to enter on the CNC control panel. If the program is very simple and only processes one, the program is not saved. MDI can be used to input segments one by one and segment by segment. In addition, the workpiece origin, tool parameters, offset amount, and various compensation amounts used in the program must also be input before processing.
(5) Editing the program If you need to modify the program, you need to edit it. At this time, set the mode selection switch to the edit position and use the edit button to add, delete, and change. See the corresponding instructions for the editing method.
(6) Machine lock, run the program This step is to check the program. If there is an error, you will need to edit it again.
(7) Manually incremental movement of the upper workpiece and the alignment tool, continuous movement or moving the machine with a hand wheel. Set the starting point to the beginning of the program and benchmark the good tool.
(8) The start of coordinate feed for continuous machining is generally processed in memory. This method has a lower failure rate than the processing on the tape. The feed rate during machining can be adjusted with the feedrate override switch. During the machining, the feed hold button can be pressed to pause the feed motion, observe the machining situation or perform manual measurement. Press the cycle start button again to resume machining. In order to ensure that the program is correct, it should be reviewed again before processing. In the case of milling, for a flat curve workpiece, a pencil can be used instead of the workpiece contour on the paper, which is more intuitive. If the system has a tool path simulation function, it can be used to check the correctness of the program.
(9) Operation display The position of the table or tool, the program, and the state of the machine tool are displayed on each screen of the CRT to allow the operator to monitor the machining situation.
(10) After the program output processing is completed, if the program is saved, it can be left in the CNC memory. If the program is too long, you can output the program in the memory to an external device (such as a puncher). Save on a perforated tape (or tape, disk, etc.).
(11) Shutdown generally should first shut down the machine and then shut down the system.
Precautions during the operation of CNC milling machine
(1) Check each time before starting the machine whether the lubricating oil in the lubricating oil pump is sufficient. Whether the air compressor is turned on, whether the mechanical oil used for the cutting fluid is sufficient, and the like.(2) When starting up, first turn on the main power, then press the open button in the CNC power supply to rotate the emergency stop button clockwise. After all the functions of the milling machine have been detected (a row of red LEDs on the lower operation panel is turned off), press the machine button to reset the milling machine and be on standby.(3) During manual operation, it is important to always note that the Z axis must be in the lift position before moving in the X and Y directions. During the movement, you can't just look at the change of the coordinate position in the CRT screen, but watch the movement of the tool. After the tool moves into position, look at the CRT screen for fine adjustment.
(4) In the programming process, for beginners, try to use the G00 command as little as possible, especially in the X, Y, Z three-axis linkage, more attention should be paid. When the knife is emptied, the movement of the Z axis should be separated from the movement of the X and Y axes, that is, the knife is lifted more and less obliquely inserted. Sometimes, due to oblique insertion, the tool will hit the workpiece and the tool will be destroyed.
(5) When using a computer for serial communication, you need to: First open the milling machine, then open the computer; Turn off the computer first, then turn off the milling machine. Avoid milling machines in the process of switching, impacting the computer due to instantaneous changes in current.
(6) When using the DNC (transfer between computer and milling machine) function, pay attention to the memory capacity of the milling machine. Generally, the total number of bytes transferred from the computer to the milling machine should be less than 23kB. If the program is long, it must be processed by the computer while transmitting, but the block number must not exceed N9999. If the program segment exceeds 10,000, you can cancel the block number with the help of the program editing function in MASTERCAM.
(7) When the milling machine has an alarm, it is necessary to find the cause according to the alarm number and release the alarm in time. Do not shut down the device, otherwise it will still be in alarm state after booting.
Using the edge finder to set the knife, the detailed steps are as follows:
X, Y to the knife
1. Mount the workpiece on the machine table through the clamp. When clamping, the measurement position of the edge finder should be left on all four sides of the workpiece.
2, quickly move the workbench and the spindle, so that the edge finder probe is close to the left side of the workpiece;
3, use the fine adjustment operation, let the probe slowly touch the left side of the workpiece until the edge finder emits light, and record the X coordinate value in the machine coordinate system at this time, such as -310.300;
4. Raise the edge finder to the upper surface of the workpiece, and quickly move the table and the spindle so that the probe is close to the right side of the workpiece;
5, use the fine-tuning operation, let the probe slowly touch the left side of the workpiece until the edge-trigger emits light, and record the X coordinate value in the mechanical coordinate system at this time, such as -200.300;
6. If the diameter of the probe is 10mm, the length of the workpiece is -200.300-(-310.300)-10=100. According to this, the X coordinate value of the workpiece coordinate origin W in the machine coordinate system is -310.300+100/2+5= -255.300;
7. Similarly, the Y coordinate value of the workpiece coordinate system origin W in the machine coordinate system can be measured.
Z to the knife
1. Remove the edge finder and install the tool used for machining on the spindle;
2. Place the Z-axis setter (or the fixed height of the tool block, the same below) on the upper surface of the workpiece;
3. Move the spindle quickly so that the end face of the tool is close to the upper surface of the Z-axis setter;
4. Use the fine adjustment operation to make the end face of the tool slowly touch the upper surface of the Z axis setter until its pointer indicates zero position.
5, note the Z value in the machine coordinate system at this time, such as -250.800;
6. If the height of the Z-axis setter is 50mm, the Z coordinate of the workpiece coordinate system origin W in the machine coordinate system is -250.800-50-(30-20)=-310.800.
(3) Input the measured X, Y, and Z values into the machine workpiece coordinate system storage address (usually use the G54-G59 code to store the tool setting parameters).
matters needing attention
(1) Adopt the correct tool setting tool according to the processing requirements to control the tool setting error;
(2) During the tool setting process, the precision of the tool setting can be improved by changing the fine adjustment feed amount;
(3) Care must be taken when setting the knife, especially pay attention to the direction of movement to avoid the risk of collision;
(4) The tool setting data must be stored in the storage address corresponding to the program to prevent serious consequences due to the call error.
Second, the input and modification of the tool compensation value
The tool radius compensation value and the tool length compensation value are input to the storage location corresponding to the program according to the actual size and position of the tool.
It should be noted that the correctness of the compensated data, the correctness of the symbol and the correctness of the address where the data is located will threaten the processing, resulting in a collision risk or processing scrap.
