In the mold factory, the CNC machining center is mainly used for the processing of key mold parts such as mold cores, inserts, and copper. The quality of mold cores and inserts directly determines the quality of the molded part of the mold. The quality of copper processing directly restricts the influence of EDM processing. For the guarantee of CNC machining quality, the key lies in the preparation before machining. For this position, in addition to rich machining experience and mold knowledge, we must also pay attention to good communication at work, especially with the production team and colleagues .

 

▌ CNC machining process

1) Read the drawings and procedures list

2) Transfer the corresponding program to the machine tool

3) Check the program header, cutting parameters, etc.

4) Determining the processing size and allowance of the process 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 cutting tools and cutting parameters

9) Reasonable clamping of tools

10) Safe trial cutting method

11) Observation of processing

12) Adjustment of cutting parameters

13) Problems in the processing process and timely feedback from the corresponding personnel

14) Inspection of workpiece quality after processing

 

▌ Precautions before processing

1) For the new mold, the processing drawing must meet the requirements and the data must be clear; the processing drawing of the new mold must be signed by the supervisor, and the columns of the processing drawing have been filled in.

 

2) The workpiece has the qualified 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 procedure sheet clearly and confirm whether the procedure is consistent with the requirements of the drawing. If there is any problem, you must work with the programmer and production team to solve the problem.

 

5) According to the material and size of the workpiece, judge the rationality of the programmer's choice of tools for roughing or smoothing. If the application of the tool is found to be unreasonable, the programmer should be notified immediately to make corresponding changes to improve the processing efficiency and workpiece processing accuracy.

 

▌ Precautions for clamping workpiece

1) When clamping the workpiece, pay attention to the position of the code and the proper extension length of the nut and bolt on the pressure plate. In addition, the screw must not be top or bottom when locking the angle.

 

2) Tong Gong is generally used for locking plate processing. Before using the machine, check the opening number on the program sheet to ensure that it matches. At the same time, check whether the receiving plate screw is tightened.

 

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

 

4) To clamp the workpiece according to the figure shape of the program sheet and the data of the workpiece size, you must pay attention: the writing method of the workpiece size data is XxYxZ. At the same time, if there is a part drawing, you must check the graphics of the program list and the part drawing Whether it matches, pay attention to which direction to go out, and the pendulum of X and Y axis.

 

5) When clamping the workpiece, you must 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 the size of the part drawing.

 

6) Clean the workbench and the bottom of the workpiece before loading the workpiece. Use oilstone to push off the burrs and damaged positions on the machine table and workpiece surface.

 

7) When coding the coding, make sure that the coding is not injured by the knife, and communicate with the programmer if necessary. At the same time, if the bottom pad is square, the code must be aligned with the pad square to achieve the purpose of force balance.

 

8) When using a vise to clamp, you must know the cutting depth of the tool to prevent the clamped position from being too long or too short.

 

9) The screw must be placed in the T-block, and only a part of the thread must not be used. If the screw is to be connected, the upper and lower screws must use half of the joint thread. The thread of the nut on the pressure plate must be fully used, and no only a few threads Thread.

 

10) When setting the Z depth number, you must see the position of the program single touch number and the data of the highest point of Z. After entering the data into the machine tool, you must check it again.

 

▌ Precautions for clamping tools

1) The tool must be clamped firmly and not too short in the handle.

 

2) Check whether the tool meets the requirements each time before lifting the tool. The length of the tool should be determined according to the machining depth indicated by the program sheet. Generally, it should be slightly longer than the machining depth of 2mm and whether the tool holder collides.

 

3) When the processing depth is very deep, you can communicate with the programmer, and use the method of two cable cutters as appropriate, that is, first obtain half to 2/3 of the length, and then obtain a longer length when the processing reaches a deeper position. This can improve processing efficiency.

 

4) When using an extended cable nozzle, you should especially know the depth of the knife and the required knife length.

 

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

 

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

 

7) When the program is interrupted or the tool must be re-calibrated again, pay attention to whether the depth can be connected to the front. Generally, you can first increase the line by 0.1mm, and then adjust it according to the situation.

 

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

 

▌ Matters needing attention in correcting the workpiece

1) When the workpiece is dragging the table, you must pay attention to the verticality, drag one side to level, and then drag the vertical side.

 

2) When the workpiece is scored, it must be scored twice for verification.

 

3) After scoring and hitting the number, check the center position according to the outline size and the size on the part drawing provided in the program sheet.

 

4) All workpieces must be centered by the centering method, and the zero position must be centered by the centering method on the side of the workpiece and then moved to the side, and the margins on both sides must be consistent. If unilateral access is required under special circumstances, it must be confirmed by the production team again to pass. After taking the count on one side, remember to compensate the radius of the center bar.

 

5) The zero input of the workpiece center must be the same as the three-axis center of the workstation computer diagram.

 

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▌ Matters needing attention during processing

1) When the margin on the top surface of the workpiece is too large, when using a large knife to manually remove the margin, remember not to deepen the gong.

 

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

 

3) Trial cut the program in the following way:

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

b) Control "Quick Shift" to 25% and feed to 0%;

c) When the tool approaches (about 10mm) the machined surface, stop the machine;

d) Check whether the remaining stroke and program are correct;

e) After turning on again, place one hand on the pause switch, ready to stop at any time, and control the feed speed with the other hand;

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.

g) After the machining and cutting are smooth and stable, adjust the controls back to the normal state.

4) After entering the program name, copy back the program name on the screen with a pen, and check it with the program list. When opening the program, pay attention to check whether the tool diameter in the program is consistent with the program list, and sign on the program list. Fill in the file name and the size of the tool diameter immediately in the column, and it is forbidden to fill in after or before.

 

5) In principle, NC technicians are not allowed to leave when the workpiece is roughing. If you have to leave when changing tools or assisting in adjusting other machine tools, please ask other NC team members or come back regularly for inspection.

 

6) When doing middle light, the NC technician should pay special attention to the places that were not opened during roughing to prevent the tool from hitting this area.

 

7) Cut the program. If the program is interrupted during processing and too much time is wasted when it is executed from the beginning, the team leader and the programmer should be notified to modify the program and cut off the executed part.

 

8) The program is abnormal. If there is an abnormal situation in the program and you are not sure, you can hang it high to observe the process, and then decide the next action.

 

9) The NC technician can adjust the travel speed and rotation speed provided by the programmer during the processing. However, special attention should be paid to the speed of small pieces of copper when exposed to thick, so as to avoid the loosening of the workpiece due to oscillation.

 

10) During the processing of the workpiece, the NC technician should check with the parts drawing to see if there is any abnormality. Once the two are found to be inconsistent, they must immediately shut down and notify the team leader to check whether there are errors.

 

11) When machining with a tool longer than 200mm, attention must be paid to issues such as allowance, feed depth, speed, and travel speed to avoid tool swinging. At the same time, the travel speed of the corner position should be controlled.

 

12) If the tool diameter is required to be tested on the procedure 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 tool change immediately.

 

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

 

14) Process errors are the main reasons for wasting time: wrong use of inappropriate tools, incorrect processing sequence arrangement, wasting time in locations that do not require processing or non-computer processing, improper processing conditions (speed too slow, empty cutters) , The tool path is too dense, the feed is too slow, etc.), when the above event occurs, you can contact the program.

 

15) During the machining process, attention must be paid to the wear and tear of the tool, and the blade or tool should be replaced appropriately. After replacing the blade, pay attention to whether the processing boundary is consistent.

 

▌ Matters needing attention after processing

1) Confirm that every procedure and every instruction required by the procedure 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, perform a self-check of the size of the workpiece according to the part drawing or process drawing, and find the error in time.

 

3) Check whether there are any abnormalities in each position of the workpiece. If in doubt, notify the NC team leader.

 

4) The team leader, programmer, and production team leader must be notified of larger workpieces to get off the machine.

 

5) Pay attention to safety when the workpiece is off the machine, especially the workpiece and the NC machine should be protected when the larger workpiece is off the machine.

 

▌ Differentiate treatment of machining accuracy requirements

Finished surface quality:

 

1) Mold core and insert

2) Tong Gong

3) Avoid vacancies in thimble plate support holes, etc.

4) Eliminate the phenomenon of vibration

 

Finished size:

 

1) The measurable size must strictly implement self-inspection after processing

2) When processing for a long time, the wear of the tool should be considered, especially the sealing position, etc.

3) For fine finishing, use new cemented carbide tools as much as possible

4) Determine the saving modulus after finishing according to the processing requirements

5) Confirmation of production and quality after processing

6) According to the processing requirements, control the tool loss during the processing of the sealing position

 

▌ Take over

1) Confirm the operating conditions of the shift, including processing conditions, mold conditions, etc.

2) Confirm whether the equipment is working properly during the shift.

3) Other handover and confirmation, including drawings, program sheets, tools, measuring tools, fixtures, etc.

 

▌ Workplace organization

1) In accordance with 5S requirements.

2) Cutting tools, measuring tools, fixtures, workpieces, tools, etc. are arranged neatly.

3) Cleaning of the machine tool.

4) Clean the floor of the workplace.

5) Return to warehouse of processed tools, idle tools and measuring tools.

6) The processed workpieces are sent to quality inspection or corresponding department.