6 steps to operate a CNC machining center, learn to become a CNC expert!

1. Start-up preparation

After the machine tool is turned on or reset by pressing emergency stop, the machine tool first returns to its reference zero position (namely, zero return) so that the machine tool has a reference position for its subsequent operations.

2. Clamping the workpiece

Before the workpiece is clamped, the surfaces should be cleaned, and there should be no oil, 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 smoothed by a grinder to make it smooth and flat. The code iron and nut must be sturdy and able to clamp the work piece reliably. For some small work pieces that are difficult to clamp, they can be clamped directly on the vise; the workbench of the machine tool should be clean and free of iron filings, dust, and oil; the shim is normal Place it on the four corners of the workpiece, and for the workpiece with too large span, it is necessary to add a contour shim in the middle. According to the size of the drawing, use a drawing rule 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 operation guide, consider avoiding the processed parts and the situation where the tool head may touch the fixture during processing.

After the workpiece is placed on the horn, the reference surface of the workpiece must be drawn according to the requirements of the drawing, and the verticality of the workpiece that has been ground on all six sides must be checked.

After the workpiece is pulled, the nut must be tightened to prevent the workpiece from being shifted during processing due to the unstable clamping; pull the table again to make sure that the error is not out of tolerance after clamping.

The workpiece touch number can use the touch number head to set the reference zero for the clamped workpiece. The touch number head can be photoelectric and mechanical. There are two methods: the number of intermediate hits and the number of unilateral hits. The steps for the intermediate hits are as follows: photoelectric static, mechanical speed 450~600rpm. Manually move the X-axis of the worktable with the middle touch to make the touch head touch 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 stage makes the digital head touch the other side of the workpiece. When the digital head just touches the workpiece, write down the relative coordinates at this time.

According to its relative value, subtract the diameter of the bumper (that is, the length of the workpiece), and check whether the length of the workpiece meets the requirements of the drawing.
Divide this relative coordinate number by 2, the obtained value is the middle value of the X axis of the workpiece, and then move the worktable to the middle value of the X axis, and set the relative coordinate value of the X axis of 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. Once again, carefully check the correctness of the data. The steps for setting the zero position of the workpiece Y axis are the same as the operation of the X axis.

3. Prepare all tools according to the programming operation guide

According to the tool data in the programming operation guide, replace the tool to be processed, let the tool touch the height measuring device placed on the reference surface, 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 machine coordinate Z value of this point in one of G54~G59. This completes the zero setting of the X, Y, and Z axes of the workpiece. Once again, carefully check the correctness of the data.
The one-side touch count also touches one side of the X and Y axes of the workpiece according to the above method. The relative coordinate value of the X and Y axes of this point is offset. The radius of the touch head is the zero position of the X and Y axes. The mechanical coordinates of the X and Y axes are marked in one of G54~G59. Once again, carefully check the correctness of the data.

Check the correctness of the zero point, move the X and Y axes to the side suspension of the workpiece, and visually check the correctness of the zero point according to the size of the workpiece.

Copy the program file to the computer according to the file path of the programming operation guide.

4. Setting of processing parameters

N=1000×V/(3.14×D) N: Spindle speed (rpm/min) V: Cutting speed (m/min) D: Tool diameter (mm) Processing feed rate setting: F=N×M× Fn

F: Feed rate (mm/min) M: Number of tool edges Fn: Cutting amount of the tool (mm/revolution) Setting of cutting amount per edge: Fn=Z×Fz

Z: The number of blades of the tool Fz: The cutting amount of each blade of the tool (mm/revolution)

5. start processing

At the beginning of each program, you must carefully check whether the tool used is the tool specified in the programming guide. When starting processing, the feed speed should be adjusted to the minimum, single block execution, fast positioning, tool drop, and feed must be concentrated. Put your hand on the stop button and stop immediately if there is a problem. Pay attention to the direction of the tool movement to ensure safe feeding. Knife, and then slowly increase the feed speed to a suitable level, and at the same time add coolant or cold air to the tool and the workpiece. Do not leave too far away from the control panel when roughing. If there is any abnormality, stop the machine for inspection in time. Pull the meter again after roughing, to make sure that the workpiece is not loose. If there is, it must be re-calibrated and touched. Continuously optimize the processing parameters during the processing to achieve the best processing results. Because this process is a key process, after the workpiece is processed, it should be measured whether its main dimensions are consistent with the drawing requirements. If there is any problem, immediately notify the team leader or programmer to check and solve it. After passing the self-inspection, it can be removed. Must be sent to the inspector for special inspection.

Processing type: Hole processing: Before drilling on the machining center, you must first use a center drill to locate, then use a drill that is 0.5~2mm smaller than the size of the drawing, and finally use a suitable drill for finishing.

Reaming processing: When reaming the workpiece, you must first use a center drill to locate, then use a drill with a size of 0.5~0.3mm smaller than the drawing size to drill, and finally ream with a reamer. When reaming, pay attention to controlling the spindle speed. Within 70~180rpm/min.
Boring processing: To boring the workpiece, first use a center drill to locate, then use a drill with a size of 1~2mm smaller than the drawing to drill, and then use a rough boring tool (or milling cutter) to process to only one side 0.3mm For the left and right machining allowance, use the fine boring tool with the pre-adjusted size to perform the fine boring. The last time the fine boring allowance cannot be less than 0.1mm.

Direct numerical control (DNC) operation: before DNC numerical control processing, the workpiece should be clamped, the zero position should be set, and the parameters should be set. Open the processing program to be transferred in the computer to check, then let the computer enter the DNC state, and enter the file name of the correct processing program. Master micro signal: Mujuren presses the TAPE button and the program start button on the processing machine tool, and the machine tool controller displays the flashing LSK word. Press the enter keyboard on the computer to perform DNC data transmission processing.

6. Content and scope of workers’ self-inspection

The processor must read the content of the process card clearly before processing, clearly know the part, shape, and dimensions of the workpiece to be processed, and know the processing content of the next process.

Before the workpiece is clamped, the size of the blank should be measured whether it meets the requirements of the drawing. When the workpiece is clamped, it must be carefully checked whether its placement is consistent with the programming operation guide.

The self-check should be carried out in time after the rough machining is completed, so that the data with errors can be adjusted in time. The content of the self-inspection is mainly the position and size of the processing part. Such as: whether the workpiece is loose; whether the workpiece is correctly centered; whether the size from the processing part to the reference edge (reference point) meets the requirements of the drawing; the size of the position between the processing parts. After checking the position and size, the roughing shape ruler should be measured (except for the arc).

Finish machining is performed after rough machining self-inspection. After finishing processing, workers should conduct self-inspection on the shape and size of the processed parts: check the basic length and width dimensions of the processed parts of the vertical surface; measure the basic point size marked on the drawing for the processed parts of the inclined surface.
After the worker completes the self-inspection of the workpiece and confirms that it is in compliance with the drawings and process requirements, the workpiece can be removed and sent to the inspector for special inspection.