Operation steps of CNC machining center

1. Start-up preparation
Every time the machine tool is turned on or reset by emergency stop, it first returns to the reference zero position of the machine tool (ie, return to zero), so that the machine tool has a reference position for its subsequent operations.
2. Clamping the workpiece
Before the workpiece is clamped, all surfaces should be cleaned, and there should be no oil stains, iron filings and dust, and the burrs on the surface of the workpiece should be removed with a file (or oil stone).
The high-speed rail used for clamping must be ground by a grinder to make it smooth and flat. The code iron and nut must be strong and can clamp the workpiece reliably. For some small workpieces that are difficult to clamp, they can be directly clamped on the tiger; the machine tool table should be clean and free of iron filings, dust and oil; At the four corners of the workpiece, it is necessary to add equal-height horns in the middle for workpieces with large spans.
According to the size of the drawing, use a drawing ruler to check whether the length, width and height of the workpiece are qualified.
When clamping the workpiece, according to the clamping and placement method of the programming work instruction, it is necessary to consider avoiding the processing part and the situation that the cutter head may hit the fixture during processing.
After the workpiece is placed on the bolster, the reference surface of the workpiece should be pulled according to the requirements of the drawing, and the verticality of the workpiece that has been ground on all six sides should be checked.
After the workpiece is pulled, the nut must be tightened to prevent the workpiece from shifting during processing due to weak clamping; pull the watch again to make sure that the error is within tolerance after clamping.

3. The number of workpiece touches
For the clamped workpiece, the touch head can be used to determine the reference zero position for processing, and the touch head can be of photoelectric type and mechanical type. There are two kinds of methods: middle touch number and unilateral touch number. The steps of middle touch number are as follows:
Photoelectric static, mechanical rotation 450~600rpm. Manually move the X-axis of the worktable in the middle of the touch, so that the touch head touches one side of the workpiece. When the touch head just touches the workpiece and the red light is on, set the relative coordinate value of this point to zero; then move the work manually. The X-axis of the table makes the colliding head touch the other side of the workpiece. When the colliding head just touches the workpiece, record the relative coordinates at this time.
According to its relative value minus the diameter of the collision head (that is, the length of the workpiece), check whether the length of the workpiece meets the requirements of the drawing.
Divide this relative coordinate number by 2, and the obtained value is the middle value of the workpiece X axis, and then move the worktable to the middle value on the X axis, and set the relative coordinate value of the X axis at this point to zero, this point is the workpiece The zero position on the X axis.
Carefully record the mechanical coordinate value of the zero position on the X axis of the workpiece in one of G54~G59, and let the machine tool determine the zero position on the X axis of the workpiece. Double check the correctness of the data again. The steps of workpiece Y-axis zero setting are the same as the X-axis operations.
Four, workpiece CAM software programming
The programmer selects the workpiece to be processed, programs it through the CAM software WorkNC, generates a tool path, and checks the tool path interference through the WorkNC simulation module. After the interference check, post-processing is performed to generate a safe and stable NC code, which is transmitted to the workshop.


5. Prepare all the tools according to the programming work instructions
According to the tool data in the programming work instruction, replace the tool to be processed, let the tool touch the height measuring device placed on the reference plane, and set the relative coordinate value of this point to zero when the red light of the measuring device is on. Move the tool to a safe place, manually move the tool down 50mm, and set the relative coordinate value of this point to zero again, this point is the zero position of the Z axis.
Record the mechanical coordinate Z value of this point in one of G54~G59. This completes the zero setting of the workpiece X, Y, and Z axes. Double check the correctness of the data
The unilateral touch is also to touch one side of the X and Y axes of the workpiece according to the above method, and offset the relative coordinate value of the X and Y axes of this point. The radius of the touch head is the zero position of the X and Y axes, and finally put a point. The machine coordinates of the X and Y axes are marked in one of G54~G59. Double check the correctness of the data again.
Check the correctness of the zero point, move the X and Y axes to the side overhang of the workpiece, and visually check the correctness of the zero point according to the size of the workpiece.
Copy the program files to the computer according to the file path of the programming work instruction.
6. Setting of processing parameters
Spindle speed setting during machining: N=1000×V/(3.14×D)
N: Spindle speed (rpm/min)
V: Cutting speed (m/min)
D: Tool diameter (mm)
Processing feedrate setting: F=N×M×Fn
F: Feed rate (mm/min)
M: Number of tool edges
Fn: Cutting amount of the tool (mm/rev)
Setting of cutting amount per edge: Fn=Z×Fz
Z: the number of edges of the tool
Fz: Cutting amount of each edge of the tool (mm/rev)

7. Start-up processing
At the beginning of each program, it must be carefully checked whether the tool used is the one specified in the programming instruction. When starting processing, the feed speed should be adjusted to the minimum, executed in a single block, and must be concentrated when positioning quickly, dropping the tool, and feeding the tool. If there is a problem with the stop button, stop immediately. Then slowly increase the feed rate to a suitable level, and at the same time add coolant or cold air to the tool and workpiece.
When starting rough machining, it should not be too far away from the control panel. If there is an abnormal phenomenon, it should be stopped and checked in time.
Pull the watch again after opening to make sure that the workpiece is not loose. If there is, it must be re-calibrated and touched.
In the process of processing, the processing parameters are continuously optimized to achieve the best processing effect.
Because this process is a key process, after the workpiece is processed, it should be measured whether its main dimensions are consistent with the requirements of the drawing. If there is a problem, immediately notify the team leader or programmer to check and solve it, and it can be removed after passing the self-inspection. It must be sent to the inspector for special inspection.

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