Summary of CNC machining experience, what is CNC machining

CNC processing , also known as CNC processing, refers to processing using CNC processing tools. Because CNC machining is programmed and controlled by computers, CNC machining has the advantages of stable processing quality, high processing accuracy, high repeatability accuracy, complex model processing, and high processing efficiency. In the actual processing process, human factors and operating experience will greatly affect the final processing quality. Next, let’s take a look at the twelve valuable experiences summarized by an experienced driver with ten years of CNC processing experience...

1. How to divide the CNC processing process?

The division of CNC CNC machining processes can generally be carried out in the following ways:

1. The tool centralized sorting method is to divide the process according to the tool used, and use the same tool CNC to process all the parts that can be completed. In other parts where they can be completed with the second knife and the third knife. This can reduce the number of tool change times, compress the time of the space, and reduce unnecessary positioning errors.

2. For parts with a lot of CNC processing contents by processing part sequence method, the machining part can be divided into several parts according to their structural characteristics, such as inner shape, outer shape, curved surface or flat surface, etc. Generally, the plane and positioning surface are first processed, and then the holes are processed; the simple geometric shapes are processed first, and then the complex geometric shapes are processed first, and then the parts with higher accuracy requirements are processed.

3. For parts that are prone to CNC processing deformation by using the rough and fine CNC processing sequence method, the deformation may occur after rough processing needs to be tidyed. Therefore, generally speaking, the process must be performed for rough and fine processing. separate. To sum up, when dividing the process, you must flexibly grasp the structure and processability of the parts, the functions of the machine tool, the number of CNC CNC machining contents of the parts, the number of installations and the production organization status of the unit. It is also recommended to adopt the principle of process concentration or process dispersion. It should be determined based on actual conditions, but it must be reasonable. If you want to learn UG processing and programming knowledge in group 565120797, you can help you.

2. What principles should be followed for the arrangement of CNC processing order?

The processing sequence should be arranged according to the structure of the part and the blank condition, as well as the need for positioning and clamping, with the focus on the rigidity of the workpiece not being damaged. The order should generally be carried out according to the following principles:

1. of the previous process The CNC machining cannot affect the positioning and clamping of the next process. If a general machine tool machining process is interspersed in the middle, it should also be considered comprehensively.

2. First perform the inner cavity processing step, and then perform the outer cavity processing step.

3. It is best to be connected to the same positioning, clamping method or the same knife CNC processing process to reduce the number of repeated positioning, the number of tool changes and the number of moving pressure plates.

4. For multiple processes carried out in the same installation, processes with less rigid damage to the workpiece should be arranged first.

3. Which aspects should be paid attention to when determining the clamping method of workpieces?

When determining the positioning reference and clamping scheme, the following three points should be paid attention to:

1. Strive to unify the benchmarks of design, process, and programming and calculation.

2. Minimize the number of clamping times and try to achieve the ability to process all the surfaces to be processed after one positioning.

3. Avoid using manual adjustment schemes for occupancy.

4. The fixture should be open and its positioning and clamping mechanism cannot affect the tooling (such as collision) during CNC processing. In such cases, clamping can be done by using a vise or a bottom plate pulling screw.

4. How to determine the tool alignment point is more reasonable? What is the relationship between the workpiece coordinate system and the programming coordinate system?

1. The tool point can be set on the part to be processed, but note that the tool point must be the reference position or the finished part. Sometimes, the tool point is destroyed by CNC processing after the first process, which will lead to the second There is no way to find the tool point after the process and the tool point afterward. Therefore, when adjusting the tool in the first process, it is necessary to set a relative tool position where there is a relatively fixed size relationship with the positioning reference, so that the relative position relationship can be based on their relative position relationship. Retrieve the original point of the knife. This relative tool position is usually located on the machine tool table or fixture. The selection principles are as follows:

(1) It is easy to find the right.

(2) Easy to program.

(3) The tool setting error is small.

(4) It is convenient to check during processing and can be checked.

2. The origin position of the workpiece coordinate system is set by the operator himself. After the workpiece is clamped, it is determined by tool setting, which reflects the distance position relationship between the workpiece and the zero point of the machine tool. Once the workpiece coordinate system is fixed, it will generally not change. The workpiece coordinate system and the programming coordinate system must be unified, that is, the workpiece coordinate system and the programming coordinate system are consistent during processing.

5. How to choose the path?

The tooling route refers to the movement trajectory and direction of the tool relative to the part to be processed during CNC machining. The rational choice of processing route is very important because it is closely related to the CNC machining accuracy and surface quality of the parts. When determining the path of the tool is the following main considerations:

1. Ensure the machining accuracy requirements of parts.

2. Convenient numerical calculations and reduce programming workload.

3. Seek the shortest CNC machining route to reduce empty knife time to improve CNC machining efficiency.

4. Minimize the number of program segments.

5. To ensure the roughness of the workpiece contour surface CNC after processing, the final contour should be arranged to be continuously processed with the last tool.

6. The tool's advance and retreat (cutting and cutting out) route should also be carefully considered to minimize the cutter stop at the contour (sudden change in cutting force causes elastic deformation) and leave marks, and avoid vertically falling on the contour surface. The knife scratches the workpiece.

6. How to monitor and adjust during CNC processing?

After the workpiece is rectified and the program debugging is completed, it can enter the automatic processing stage. During automatic machining, the operator must monitor the cutting process to prevent abnormal cutting from causing workpiece quality problems and other accidents.

Monitoring the cutting process mainly considers the following aspects:

1. The main consideration of rough machining is to quickly remove the excess excess on the surface of the workpiece. During the automatic machining of the machine tool, the tool automatically cuts according to the set cutting amount according to the predetermined cutting track. At this time, the operator should pay attention to observe the changes in the cutting load during the automatic processing process through the cutting load meter, adjust the cutting usage according to the tool's bearing capacity, and maximize the efficiency of the machine tool.

2. Monitoring of cutting sound during cutting process. During the automatic cutting process, generally when cutting begins, the sound of the tool cutting workpiece is stable, continuous and light, and the movement of the machine tool is stable at this time. As the cutting process progresses, when there are hard spots on the workpiece, tool wear or tool clamping, the cutting process becomes unstable. The unstable manifestation is that the cutting sound changes, and there will be mutual impact between the tool and the workpiece. The machine tool will vibrate. At this time, the cutting usage and cutting conditions should be adjusted in time. When the adjustment effect is not obvious, the machine tool should be suspended and the condition of the tool and workpiece should be checked.

3. Monitoring and finishing process is mainly to ensure the processing size and processing surface quality of the workpiece, with a high cutting speed and a large feeding capacity. At this time, we should pay attention to the impact of the accumulation of chips on the processing surface. For cavity processing, we should also pay attention to the over-cutting and handing of the knife at the corners. To solve the above problems, first, pay attention to adjusting the spray position of the cutting fluid so that the processing surface is always in cooling conditions; second, pay attention to observing the quality of the processed surface of the workpiece, and avoid quality changes as much as possible by adjusting the cutting usage. If the adjustment still has no obvious effect, the machine should be shut down to check whether the original procedures were compiled reasonably. It is particularly important to note that when pausing inspection or shutting down inspection, pay attention to the position of the tool. If the tool stops during cutting, and the sudden spindle stops, the tool marks will occur on the surface of the workpiece. Generally, the shutdown should be considered when the tool leaves the cutting state.

4. Tool monitoring The quality of the tool largely determines the processing quality of the workpiece. During automatic machining and cutting, the normal wear and abnormal damage of the tool must be judged through sound monitoring, cutting time control, pause inspection during cutting, and workpiece surface analysis. The tool should be processed in a timely manner according to the processing requirements to prevent processing quality problems caused by the tool's failure to process in a timely manner.

7. How to reasonably choose machining tools? How many major factors are there in cutting amount? How many materials are there? How to determine the tool's rotation speed, cutting speed, and cutting width?

1. When milling, you should choose a non-remelting cemented carbide end mill or end mill. Generally, when milling, try to use secondary tooling processing. It is best to use end milling cutters to roughly mill the first tooling, and continuously run the tooling along the surface of the workpiece. The width of each tool is recommended to be 60%-75% of the tool diameter.

2. End milling cutters and end milling cutters with cemented carbide inserts are mainly used to process bosses, grooves and box mouth surfaces.

3. Ball knives and round knives (also known as round nose knives) are often used to process curved surfaces and varying beveled contours. Ball knives are mostly used for semi-finishing and finishing. Round knives with cemented carbide tools are mostly used for thickening.

8. What is the function of the processing program sheet? What should be included in the processing program sheet?

1. The processing program list is one of the contents of CNC machining technology design, and it is also a procedure that needs to be followed and executed by the operator. It is a specific description of the processing program. The purpose is to allow the operator to clarify the content of the program, the clamping and positioning methods, and the various processing. The tools used in the program should be noted.

2. In the machining program list, it should include: drawing and programming file names, workpiece names, mounting sketches, program names, tools used in each program, maximum cutting depth, and processing properties (such as rough processing or finishing processing) , theoretical processing time, etc.

9. What preparations should be made before CNC programming?

After determining the processing technology, you should understand:

1. Workpiece clamping method;

2. The size of the workpiece bladder--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

3. Materials of the workpiece------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

4. What are the knives in stock---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

10. What are the principles for setting safety heights in programming?

Principle of setting safety height: generally higher than the highest surface of the island. Or set the programming zero point at the highest surface, which can also minimize the risk of hitting the knife.

11. Why do you need to post-process after the tool path is compiled?

Because the address codes that can be recognized by different machines and NC program formats are different, the correct post-processing format must be selected for the machine tool used to ensure that the compiled programs can run.

12. What is DNC communication?

The methods of program delivery can be divided into CNC and DNC. CNC refers to the program being transported to the memory of the machine tool through media media (such as floppy disks, belt reader, communication line, etc.) and the program is called out from the memory during processing. Processing. Since the capacity of the memory is limited by size, when the program is large, the DNC method can be used for processing. Since the machine tool directly reads the program from the control computer during DNC processing (that is, it is done while sending), it is not subject to the capacity of the memory. Restricted by size.

1. There are three major factors in cutting usage: cutting depth, spindle speed and feeding speed. The overall principle of choosing cutting usage is: less cutting, fast feeding (that is, small cutting depth and fast feeding speed)

2. According to the classification of materials, tools are generally divided into ordinary hard white steel knives (the material is high-speed steel), coated knives (such as titanium plating, etc.), and alloy knives (such as tungsten steel, boron nitride knives, etc.).

If you want to switch from a CNC machining operator to a programmer, the above must be known. In addition to the above, do you think there is anything else you need to know? Is it important to improve efficiency? Do you also need to pay attention to avoid hitting knives or empty knives?