CNC machining, also known as numerical control machining, refers to the machining process performed using CNC tools. Since CNC machining is controlled by computers after programming, it offers advantages such as stable machining quality, high precision, high repeatability, the ability to machine complex surfaces, and high processing efficiency. In actual machining processes, human factors and operational experience significantly influence the final machining quality. Below are twelve valuable insights summarized ...
1. How to divide CNC machining processes?

The division of CNC machining processes can generally be carried out according to the following methods:
1. The centralized tool sorting method is to divide the process according to the tools used, and use the same tool to CNC machine all the parts that can be completed on the part. Use the second and third knives to complete other parts that they can accomplish. This can reduce the number of tool changes, compress the idle time, and minimize unnecessary positioning errors.
2. For parts with a lot of CNC machining content, the machining part can be divided into several parts according to their structural characteristics, such as internal shape, external shape, curved surface, or flat surface, using the machining part sorting method. Generally, flat and positioning surfaces are processed first, followed by hole processing; First process simple geometric shapes, then process complex geometric shapes; Process the parts with lower precision first, and then process the parts with higher precision requirements.
3. For parts that are prone to CNC machining deformation, the rough and fine CNC machining sequence method is used. Due to the possible deformation that may occur after rough machining, it is generally necessary to separate the processes for rough and fine machining. In summary, when dividing the process, it is necessary to flexibly grasp the structure and processability of the parts, the function of the machine tool, the amount of CNC machining content of the parts, the number of installations, and the production organization status of the unit. Another suggestion is to adopt the principle of centralized or decentralized processes, which should be determined according to the actual situation, but must strive for rationality.

2、 What principles should be followed in the arrangement of CNC machining sequence?
The arrangement of processing sequence should be considered based on the structure and blank condition of the parts, as well as the need for positioning and clamping, with the focus on ensuring that the rigidity of the workpiece is not compromised. The sequence should generally follow the following principles:
1. The CNC machining of the previous process should not affect the positioning and clamping of the next process, and the presence of universal machine tool machining processes in between should also be considered comprehensively.
2. First, proceed with the internal cavity processing sequence, followed by the external shape processing process.
3. It is best to connect the CNC machining processes with the same positioning, clamping method, or the same knife to reduce the number of repeated positioning, tool changes, and pressure plate movements.
4. Multiple processes carried out in the same installation should be arranged first for the process with minimal damage to the rigidity of the workpiece.

3、 What aspects should be considered when determining the clamping method for workpieces?
When determining the positioning reference and clamping scheme, the following three points should be noted:
1. Strive to unify the standards of design, process, and programming calculations.
2. Try to minimize the number of clamping times and achieve CNC machining of all surfaces to be machined after one positioning as much as possible.
3. Avoid using manual adjustment schemes that occupy machines.
4. The fixture should be open smoothly, and its positioning and clamping mechanism should not affect the cutting in CNC machining (such as collision). When encountering such situations, a vise or a bottom plate with screws can be used for clamping.

4、 How to determine the most reasonable cutting point? What is the relationship between the workpiece coordinate system and the programming coordinate system?
1. The tool alignment point can be set on the machined part, but it must be the reference position or a precision machined part. Sometimes, the tool alignment point is damaged by CNC machining after the first process, which can make it difficult to find the tool alignment points for the second and subsequent processes. Therefore, when aligning the tool in the first process, it is important to set a relative tool alignment position at a location with a relatively fixed dimensional relationship with the positioning reference, so that the original tool alignment point can be retrieved based on their relative positional relationship. This relative tool position is usually set on the machine tool worktable or fixture. The selection principle is as follows:
1) Finding the right one is easy.
2) Programming is convenient.
3) Small knife error.
4) Easy and traceable inspection during processing.
2. The origin position of the workpiece coordinate system is set by the operator themselves. After the workpiece is clamped, it is determined by tool alignment and reflects the distance and position relationship between the workpiece and the machine zero point. Once the workpiece coordinate system is fixed, it is generally not changed. The workpiece coordinate system and the programming coordinate system must be unified, that is, during processing, the workpiece coordinate system and the programming coordinate system are consistent.

5、 How to choose a cutting route?
The cutting path refers to the motion trajectory and direction of the tool relative to the workpiece during the CNC machining process. The reasonable choice of processing route is very important, as it is closely related to the CNC machining accuracy and surface quality of the parts. When determining the cutting route, the following points are mainly considered:
1. Ensure the machining accuracy requirements of the parts.
2. Facilitating numerical calculations and reducing programming workload.
3. Seeking the shortest CNC machining route to reduce idle time and improve CNC machining efficiency.
4. Try to minimize the number of program segments.
5. Ensure the required roughness of the workpiece contour surface after CNC machining, and the final contour should be arranged for continuous machining with the last cutting.
6. The advance and retreat path of the cutting tool (cutting in and out) should also be carefully considered to minimize tool marks caused by stopping at the contour (sudden changes in cutting force leading to elastic deformation), and to avoid cutting vertically on the contour surface and scratching the workpiece.

6、 How to monitor and adjust during CNC machining process?
After the workpiece is aligned and the program debugging is completed, it can enter the automatic machining stage. During the automatic machining process, the operator should monitor the cutting process to prevent abnormal cutting from causing quality problems and other accidents.
The monitoring of the cutting process mainly considers the following aspects:
1. The monitoring of the machining process for rough machining mainly considers the rapid removal of excess residue on the surface of the workpiece. In the automatic machining process of machine tools, the cutting tool automatically cuts according to the predetermined cutting trajectory based on the set cutting parameters. At this time, the operator should pay attention to observing the changes in cutting load during the automatic machining process through the cutting load table, adjust the cutting amount according to the tool's bearing capacity, and maximize the efficiency of the machine tool.
2. Monitoring of cutting sound during the cutting process. In automatic cutting, the sound of the cutting tool cutting the workpiece is generally stable, continuous, and light at the beginning of cutting, and the movement of the machine tool is smooth 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 manifestation of instability is that the cutting sound changes, and there will be collision sounds between the tool and the workpiece, causing the machine tool to vibrate. At this time, the cutting amount and cutting conditions should be adjusted in a timely manner. When the adjustment effect is not obvious, the machine tool should be paused to check the condition of the cutting tools and workpieces.
3. The monitoring of precision machining process is mainly to ensure the machining size and surface quality of the workpiece, with high cutting speed and large feed rate. At this point, special attention should be paid to the impact of chip deposits on the machined surface. For cavity machining, attention should also be paid to over cutting and tool allowance at corners. To solve the above problems, firstly, attention should be paid to adjusting the spraying position of the cutting fluid to keep the machined surface in a cooling condition at all times; Secondly, it is important to observe the quality of the machined surface of the workpiece and adjust the cutting parameters to avoid any changes in quality as much as possible. If the adjustment still has no significant effect, the machine should be stopped to check whether the original program is reasonable. Special attention should be paid to the position of the tool when pausing or stopping the inspection. If the cutting tool stops during the cutting process and the spindle suddenly stops rotating, it will cause tool marks on the surface of the workpiece. Generally, shutdown should be considered when the tool leaves the cutting state.
4. The quality of tool monitoring largely determines the machining quality of the workpiece. In the process of automatic machining and cutting, it is necessary to determine the normal wear condition and abnormal damage condition of the tool through methods such as sound monitoring, cutting time control, pause inspection during the cutting process, and surface analysis of the workpiece. According to the processing requirements, the cutting tools should be processed in a timely manner to prevent processing quality problems caused by untimely processing of the tools.

7、 How to choose machining tools reasonably? What are the major elements of cutting quantity? How many types of cutting tools are there? How to determine the rotational speed, cutting speed, and cutting width of the tool?
1. When milling flat surfaces, non regrinding hard alloy end mills or end mills should be selected. When milling, it is recommended to use a secondary cutting method. For the first cutting, it is best to use an end mill for rough milling, and to continuously cut along the surface of the workpiece. The recommended width for each cutting is 60% -75% of the tool diameter.
2. End mills with end mills and carbide inserts are mainly used for machining bosses, grooves, and box mouth surfaces.
3. Ball knives and round knives (also known as round nose knives) are commonly used for machining curved surfaces and variable angle contour shapes. And ball cutters are mostly used for semi precision machining and precision machining. Round knives with embedded hard alloy cutting tools are often used for rough cutting.

8、 What is the function of a processing program sheet? What should be included in the processing program sheet?
1. The machining program sheet is one of the contents of CNC machining process design, and it is also a regulation that operators need to follow and execute. It is a specific description of the machining program, with the purpose of allowing operators to clarify the content of the program, clamping and positioning methods, and issues that should be noted when selecting cutting tools for each machining program.
2. In the machining program sheet, it should include: drawing and programming file names, workpiece names, clamping sketches, program names, tools used in each program, maximum cutting depth, machining properties (such as rough machining or precision machining), theoretical machining time, etc.
9、 What preparations should be made before CNC programming?
After determining the processing technology, it is necessary to understand:
1. Workpiece clamping method;
2. The size of the workpiece blank - in order to determine the processing range or whether multiple clamping is required;
3. The material of the workpiece - in order to select which cutting tool to use for processing;
4. What are the tools in stock? To avoid modifying the program due to the lack of such tools during processing, if it is necessary to use this tool, it can be prepared in advance.
10、 What are the principles for setting a safe height in programming?
The principle of setting a safe height: generally higher than the highest surface of the island. Alternatively, the programming zero point can be set to the highest surface to minimize the risk of tool collision.

11、 Why is post-processing necessary after the tool path is created?
Because different machine tools can recognize different address codes and NC program formats, it is necessary to choose the correct post-processing format for the machine tool used to ensure that the program can run.
12、 What is DNC communication?
The method of program delivery can be divided into two types: CNC and DNC. CNC refers to the program being transported to the memory of the machine tool through media media (such as floppy disks, tape readers, communication lines, etc.) for storage, and the program being retrieved from the memory for processing. Due to the size limitation of the storage capacity, DNC can be used for processing when the program is large. As DNC processing directly reads the program from the control computer (i.e., performs while sending), it is not limited by the size of the storage capacity.
1. There are three major elements of cutting parameters: cutting depth, spindle speed, and feed rate The overall principle for selecting cutting parameters is to cut less and feed faster (i.e. cutting depth is small and feed rate is fast)
2. According to material classification, cutting tools are generally divided into ordinary hard white steel cutting tools (made of high-speed steel), coated cutting tools (such as titanium plating), and alloy cutting tools (such as tungsten steel, boron nitride cutting tools, etc.).
If you want to switch from a CNC machining operator to a programmer, these are the things you must know. Besides the above, what else do you think you need to know? Isn't it also important to improve efficiency, and to avoid collisions or empty knives.