- General steps for CNC milling machine operation
(1) Before writing or programming, the machining program of the workpiece should be compiled first. If the machining program of the workpiece is long and complex, it is best not to program on the machine tool, but to use a programming machine or computer to program, so as to avoid occupying machine time. Short programs should also be written on the program sheet.
(2) Generally, the machine tool is turned on first and then the system. In some designs, the two are interlocked, and the information cannot be displayed on the CRT without power on the machine tool.
(3) Return to the reference point For machine tools with incremental control systems (using incremental position detection elements), this step must be performed first to establish the moving reference of each coordinate of the machine tool.
(4) Adjust the machining program According to the storage medium of the program (paper tape or magnetic tape, disk), it can be input using a paper tape reader, cassette tape machine, programming machine or serial communication. If it is a simple program, it can be directly input on the CNC control panel using the keyboard. If the program is very simple and only one piece is processed, there is no need to save the program. The MDI method can be used to input and process segment by segment. In addition, the workpiece origin, tool parameters, offsets, and various compensations used in the program must also be input before processing.
(5) Program editing If the input program needs to be modified, it must be edited. At this time, set the mode selection switch to the edit position and use the edit key to add, delete, and change. For the editing method, see the corresponding manual.
(6) Lock the machine tool and run the program. This step is to check the program. If there is an error, it needs to be re-edited.
(7) Manual incremental movement, continuous movement, or hand-cranked wheel movement are used to load the workpiece and align the tool. Align the starting point to the beginning of the program and align the tool reference.
(8) Start coordinate feeding for continuous processing. Generally, the program in the memory is used for processing. This method has a lower failure rate than the program on the paper tape. The feed speed during processing can be adjusted using the feed rate switch. During processing, the feed hold button can be pressed to pause the feed movement, observe the processing situation or perform manual measurement. Press the cycle start button again to resume processing. To ensure that the program is correct, it should be reviewed again before processing. When milling, for plane curved workpieces, a pencil can be used instead of a tool to draw the workpiece outline on 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 workbench or tool, the program and the status of the machine tool are displayed using the various screens of the CRT to allow the operator to monitor the processing status.
(10) Program output After the processing is completed, if the program needs to be saved, it can be left in the CNC memory. If the program is too long, the program in the memory can be output to an external device (such as a puncher) and saved on a punched paper tape (or magnetic tape, disk, etc.).
(11) Shutdown Generally, the machine tool should be turned off first and then the system.
- Precautions during the operation of CNC milling machines
(1) Before starting the machine each time, check whether the lubricating oil in the lubricating oil pump behind the milling machine is sufficient, whether the air compressor is turned on, and whether the mechanical oil used for cutting fluid is sufficient.
(2) When starting the machine, first turn on the main power, then press the start button in the CNC power supply, turn the emergency stop button clockwise, and after the milling machine has checked all functions (the row of red indicator lights on the lower operating panel goes out), press the machine button to reset the milling machine and put it in standby mode.
(3) During manual operation, you must always pay attention to the Z axis being in the tool lifting position before moving in the X and Y directions. During the movement process, you cannot only look at the changes in the coordinate position on the CRT screen, but also observe the movement of the tool. After the tool moves into place, look at the CRT screen for fine-tuning.
(4) During programming, for beginners, try to use G00 instructions as little as possible, especially in the linkage of the X, Y, and Z axes. When the tool is in the air, the movement of the Z axis should be separated from the movement of the X and Y axes, that is, more lifting and less oblique insertion. Sometimes, when the tool is inserted obliquely, it will hit the workpiece and cause damage to the tool.
(5) When using the computer for serial communication, you should do the following: turn on the milling machine first, then the computer; turn off the computer first, then the milling machine. Avoid the impact of the computer due to the instantaneous change of current during the switching process of the milling machine.
(6) When using the DNC (transmission of programs between the computer and the milling machine) function, pay attention to the memory capacity of the milling machine. Generally, the total number of bytes of the program transmitted from the computer to the milling machine should be less than 23kB. If the program is long, the method of transferring and processing by the computer must be adopted, but the program segment number must not exceed N9999. If the program segment exceeds 10,000, the program segment number can be cancelled with the help of the program editing function in MASTERCAM.
(7) When the machine tool alarms, find the cause according to the alarm number and cancel the alarm in time. Do not shut down the machine, otherwise it will still be in the alarm state after restarting.
