Talking about some operating experience of CNC machining center

Talking about some operating experience of CNC machining center

In the mold factory, the CNC machining center is mainly used for the processing of mold cores, inserts and other key mold parts and copper components. The quality of the mold core and inserts directly determines the quality of the molding part of the mold.

The copper processing quality directly restricts the influence of EDM processing.The key to guaranteeing the quality of CNC machining lies in the preparation before processing. As far as this position is concerned, in addition to having rich processing experience and mold knowledge, good communication should also be paid attention to in the work, especially the communication with colleagues in the production team. communicate.

cnc machining operations

CNC machining process

1) Read drawings and program sheets.
2) Transfer the corresponding program to the machine tool.
3) Check the program header, cutting parameters, etc.
4) Determination of the processing size and allowance of the workpiece on the workpiece.
5) Reasonable clamping of the workpiece.
6) Accurate alignment of the workpiece.
7) Accurate establishment of workpiece coordinates.
8) Selection of reasonable tools and cutting parameters.
9) Reasonable clamping of tools.
10) Safe trial cutting method.
11) Observation of the processing process.
12) Adjustment of cutting parameters.
13) Problems during processing and timely feedback from corresponding personnel.
14) Inspection of workpiece quality after processing.

CNC machining process

Precautions before processing

1) For new molds, the processing drawings must meet the requirements, and the data is clear; the processing drawings of new molds must have the signature of the supervisor, and each column of the processing drawings has been filled.

2) The workpiece has the qualification mark of the quality department.

3) After receiving the program sheet, check whether the reference position of the workpiece is consistent with the reference position of the drawing.

4) Look at each requirement on the program sheet clearly, and confirm whether the program is consistent with the requirements of the drawings. If there is any problem, you must solve the problem together with the programmer and the production team.

5) According to the material and size of the workpiece, judge the rationality of the tool selected by the programmer for roughing or light tooling. If the tool application is found to be unreasonable, the programmer should be notified immediately to make corresponding changes in order to improve processing efficiency and workpiece processing accuracy.

Precautions for clamping workpiece

  • When clamping the workpiece, pay attention to the position of the clamp and the protruding length of the nut and bolt on the pressure plate is moderate. In addition, the screw cannot be pushed to the bottom when locking the corner clamp.

  • Copper males are generally processed for lock plates. Before starting the machine, you should check the number of cutting materials on the program sheet to ensure that they match. At the same time, you should check whether the closing plate screws are tightened.

  • For the case of receiving multiple pieces of copper material on one board, check whether the direction is correct and whether each copper material interferes during processing.

  • Clamp the workpiece according to the shape of the program sheet and the data of the workpiece size. It must be noted that the writing method of the workpiece size data is XxYxZ. Whether it matches, pay attention to which direction is going out, and the pendulum of the X and Y axes.

  • When clamping the workpiece, it is necessary to check whether the size of the workpiece meets the size requirements of the program sheet. If there is a part drawing, check whether the size of the program sheet is the same as that of the part drawing.

  • When coding, ensure that the code will not be hurt by the knife, and communicate with the programmer if necessary. At the same time, if the bottom pad is square, the size must be aligned with the square pad to achieve the purpose of force balance.

  • When clamping with a vise, you must know the machining depth of the tool to prevent the clamped position from being too long or too short.

  • The screw must be put into the T-shaped block, and only a part of the thread should not be used. If the screw needs to be connected, half of the thread of the joint must be used for the upper and lower screws, and the thread of the nut on the pressure plate must be fully used, not only a few teeth thread.

CNC machining clamping workpiece
  • When setting the Z depth number, it is necessary to clearly see the position of the single touch number in the program and the data of the highest point of Z. After inputting the data into the machine tool, it must be checked again.

Precautions for clamping tools

  • The tool should be firmly clamped and not too short in the handle.

  • Check whether the tool meets the requirements before each cable cutter. The length of the cable cutter should be determined according to the processing depth indicated in the program sheet. Generally, it should be slightly longer than the processing depth value by 2mm and whether the tool handle collides should be considered.

  • In the case of a deep processing depth, you can communicate with the programmer, and use the method of two cable cutters as appropriate, that is, first cable half to 2/3 of the length, and then cable longer when processing to a deeper position. This improves processing efficiency.

  • When using the extended cable nozzle, it is especially necessary to understand the data such as the cutting depth and the required length of the cutting tool.

  • Before the cutter head is installed on the machine, its taper matching position should be wiped clean with a cleaning cloth, and the corresponding position of the machine tool sleeve should also be cleaned to avoid iron filings on the mating surface affecting the accuracy and damaging the machine tool.

  • Usually, the tool tip setting method is adopted for the tool length (in special cases, the tool setting method is used in the tool setting), and the instructions in the program sheet should be carefully checked when setting the tool.

CNC machining clamping cutter
  • When the program is interrupted or the tool must be re-set, attention should be paid to whether the depth can be connected to the front. Generally, it can be adjusted by 0.1mm first, and then adjusted according to the situation.

  • For the rotary retractable cutter head, if water-soluble cutting fluid is used, it should be maintained with lubricating oil for several hours every half month, so that the internal parts of the cutter head can be lubricated and not worn.

Precautions for correcting and aligning workpieces

  • Pay attention to the verticality when the workpiece is dragged to the table, drag one side flat, and then drag the vertical side.

  • When the workpiece is divided, it must be verified twice.

  • After the number is divided, the median should be checked according to the outline size provided by the program sheet and the size on the part drawing.

correcting and aligning workpieces
  • All workpieces must be centered by the centering method, and the zero position on the side of the workpiece must also be centered by the centering method and then moved to the side. It is necessary to ensure that the margins on both sides are consistent. If it is necessary to take the number unilaterally under special circumstances, it must be confirmed by the production team again before it can be passed. After counting on one side, remember to compensate for the radius of the center stick.

  • The zero position input of the workpiece center must be the same as the three-axis center of the computer graphics of the workstation.

Precautions during processing

  • When the margin on the top surface of the workpiece is too large, when removing the margin by hand with a large knife, remember not to drill too deep.

  • The most important processing is the first cut, because if you operate and check carefully, you can know whether the tool length compensation, tool diameter compensation, program, speed, etc. are wrong, so as to avoid damage to the workpiece, tool and machine tool.

The 5-axis CNC milling machine cutting aluminium

Try cutting the program in the following way:

  1. a) The height of the first point is up to 100mm, use your eyes to feel whether it is correct;

  2. b) Control “rapid shift” to 25% and feed to 0%;

  3. c) When the tool is close to (about 10mm) the processing surface, stop the machine;

  4. d) Check whether the remaining itinerary and the program are correct;

  5. e) After restarting the machine, put one hand on the pause button, ready to stop at any time, and control the feed speed with the other hand;

  6. f) When the tool is very close to the workpiece surface, it can stop again, and the remaining stroke of the Z axis must be checked.

  7. g) After the processing and cutting are smooth and stable, then adjust each control back to the normal state.

  • After inputting the program name, use a pen to copy back the program name on the screen, and then check it with the program sheet. When opening the program, pay attention to check whether the tool diameter in the program is consistent with the program sheet, and sign on the program sheet Fill in the file name and tool diameter in the column immediately, and it is forbidden to fill in afterwards or in advance.

  • In principle, NC technicians are not allowed to leave when the workpiece is being roughed. In case of changing tools or assisting in the adjustment of other machine tools, etc., when it is necessary to leave, other NC team members must be asked to come back to check regularly.

  • When doing medium light, NC technicians should pay special attention to the places that were not opened during roughing, so as to prevent the tool from hitting this area.

  • Program cut. If the program is interrupted during processing and it takes too much time to run it from the beginning, the team leader and programmer should be notified to modify the program and cut off the part that has been run.

  • The program is abnormal. If there is an abnormal situation in the program and you are not sure, you can hang it up to observe the process, and then decide the next step.

  • The speed and rotation speed provided by the programmer during the machining process can be adjusted by the NC technician according to the situation. However, special attention should be paid to the fact that the speed of small pieces of copper should not be fast when the copper is exposed, so as to avoid loosening of the workpiece due to vibration.

  • During the processing of the workpiece, the NC technician should check with the part drawing to see if there is any abnormality. Once the two are found to be inconsistent, the machine must be shut down immediately to notify the team leader to check whether there is any error.

  • When machining with a tool longer than 200mm, attention must be paid to issues such as margin, feed depth, speed, and travel speed to avoid knife swinging, and the travel speed at the corner should be controlled.

  • If the tool diameter is required to be tested on the program sheet, the operator must be responsible and record the tested diameter at the same time. If it exceeds the tolerance range, it should be reported to the team leader or the tool should be changed immediately.

  • When the machine tool is in automatic operation or free, the operator should go to the workstation to understand the remaining processing programming, prepare and grind appropriate tools for the next processing, so as to avoid downtime.

  • Process errors are the main reasons for wasting time: incorrect use of inappropriate tools, errors in processing sequence, waste of time in positions that do not require processing or non-computer processing, and improper processing conditions (too slow speed, empty tool , the tool path is too dense, the feed is too slow, etc.), when the above events occur, they can be contacted with programming.

  • During the processing, it is necessary to pay attention to the wear of the tool, and the cutter grain or the tool should be replaced appropriately. After replacing the knife grain, pay attention to whether the processing boundary is consistent.

Precautions after processing

1) Confirm that each program and each instruction required by the program sheet has been completed.

2) After the processing is completed, it is necessary to check whether the shape of the workpiece meets the requirements, and at the same time conduct a self-inspection of the workpiece size according to the part drawing or process drawing, so as to find mistakes in time.

3) Check whether there is any abnormality in each position of the workpiece, and notify the NC team leader if in doubt.

4) The team leader, programmer and production team leader should be notified when a large workpiece is off the machine.

5) Pay attention to safety when the workpiece is off the machine, especially when the large workpiece is off the machine, the protection of the workpiece and the NC machine should be done well.

▌ Distinguished treatment of machining accuracy requirements

Polished surface quality:

1) Mold cores and inserts
2) Tong Gong
3) Evacuation places such as the support head hole of the thimble plate
4) Eliminate the phenomenon of knife vibration

▌ Succession:

1) Measurable dimensions must strictly implement self-inspection after processing
2) When processing for a long time, the loss of the tool should be considered, especially at the front of the batch such as the sealing position
3) New hard alloy tools should be used as much as possible for finishing
4) Determine the modulus saving after finishing according to the processing requirements
5) Confirmation of quality such as production and quality after processing
6) According to the processing requirements, control the tool loss during the processing of the sealing position

▌ Succession

1) Confirm the operation status of the shift, including processing status, mold status, etc.
2) Confirm whether the equipment works normally during work.
3) Other transfers and confirmations, including drawings, program sheets, tools, measuring tools, fixtures, etc.

▌ Organization of the workplace

1) Execute in accordance with 5S requirements.

2) Knives, measuring tools, fixtures, workpieces, tools, etc. are neatly classified.

3) Cleaning of the machine tool.

4) Cleaning of the workplace floor.

5) Restocking of processed tools, idle tools and measuring tools.

6) The processed workpiece is sent to quality inspection or corresponding department.