What is CNC machining?

12 CNC machining experience summary, what is CNC machining? 2023-04-25 13:30:31
CNC machining, also known as numerical control machining, refers to the use of numerical control machining tools for processing. Because CNC machining is programmed by the computer control processing, therefore, CNC machining has the advantages of stable processing quality, high processing precision, high repeat precision, processing complex surface, high processing efficiency. In the actual processing process, human factors and operational experience, to a large extent, will affect the final processing quality. Below, let's take a look, a ten years CNC processing experience of the old driver, summed up the twelve valuable experience....

First, how to divide cnc machining process?

The division of cnc machining procedures can generally be carried out in the following ways:

1, the tool concentration sequence method is according to the tool division process, with the same tool cnc machining parts can be completed on all parts. With a second knife and a third to do whatever else they can. This can reduce the number of tool change, compress the space time, reduce unnecessary positioning error.

2, processing parts of the order method for cnc processing content of a lot of parts, according to its structural characteristics will be processed into several parts, such as internal shape, shape, surface or plane. Generally first processing plane, positioning surface, after processing holes; First processing simple geometric shapes, then processing complex geometric shapes; First machining parts with low precision, and then machining parts with higher precision requirements.

3, with rough and fine cnc processing sequence method for cnc processing deformation parts, due to the deformation may occur after rough processing and need to be calibrated, so generally speaking, where to rough and fine processing should be separated. To sum up, in the division of the process, we must depend on the structure and technology of the parts, the function of the machine tool, the number of parts cnc processing content, installation times and the flexible grasp of the production organization of the unit. It is also suggested that the principle of process concentration or the principle of process dispersion should be determined according to the actual situation, but it must strive to be reasonable. Want to learn UG machining programming knowledge in group 565120797 can help you.

Two, cnc processing sequence arrangement should follow what principle?

The arrangement of the processing sequence should be considered according to the structure of the parts and blank condition, as well as the need for positioning clamping, focusing on the rigidity of the workpiece is not destroyed. The order should generally follow the following principles:

1. The cnc machining of the previous procedure cannot affect the positioning and clamping of the next procedure, and the processing procedure of universal machine tools interspersed between them should also be considered comprehensively.

2. Advance the machining sequence of the inner shape and cavity, and then carry out the contour machining process.

3, with the same positioning, clamping way or the same knife cnc processing process is best connected, in order to reduce the number of repeated positioning, the number of tool change and the number of moving plate.

4, in the same installation of multiple processes, should be arranged on the workpiece rigid damage small process.

Three, the workpiece clamping method should pay attention to which aspects?

The following three points should be paid attention to when determining the positioning datums and clamping schemes:

1, strive to design, process, and programming calculation of the benchmark unity.

2, as far as possible to reduce the number of clamping, as far as possible after a positioning can cnc machining out of all the surface to be processed.

3, avoid the use of manual adjustment scheme.

4, the fixture should be open, its positioning, clamping mechanism can not affect the cnc machining in the knife (such as collision), encounter this kind of situation, can be used with the vise or add the bottom plate to pull the screw clamping.

Four, how to determine the knife point is more reasonable? How does the job coordinate system relate to the programming coordinate system?

1, the cutter point can be located on the machined parts, but note that the cutter point must be the reference position or has been finished, sometimes in the first process after cnc machining of the cutter point is destroyed, will lead to the second process and after the cutter point can not find, Therefore, in the first procedure, attention should be paid to set up a relative tool position in the place where there is a relative fixed size relationship with the positioning datum, so that the original tool point can be retrieved according to the relative position relationship between them. This relative - to - tool position is usually located on the machine table or fixture. The selection principle is as follows:

1) Finding the right one is easy.

2) Easy programming.

3) Small tool setting error.

4) It is convenient and searchable to check during processing.

2, the origin position of the workpiece coordinate system is set by the operator, it is in the workpiece after clamping, through the knife to determine, it reflects the distance between the workpiece and the machine zero position relationship. 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.

Five, how to choose the knife route?

The cutting path is the motion path and direction of the tool relative to the workpiece in the process of exponential control machining. The reasonable choice of machining route is very important, because it is related to the precision and surface quality of cnc machining parts. In determining the knife route is the main consideration of the following points:

1. Ensure the machining accuracy requirements of parts.

2, convenient numerical calculation, reduce programming workload.

3. Seek the shortest cnc machining route and reduce the empty cutting time to improve cnc machining efficiency.

4. Minimize the number of program segments.

5, ensure that the workpiece contour surface cnc machining roughness requirements, the final contour should be arranged at the end of the continuous machining.

6, the advance and retreat of the tool (cut and cut out) line should also be seriously considered, in order to minimize the contour of the stop tool (cutting force sudden change caused by elastic deformation) and leave the mark, but also to avoid in the contour of the vertical tool and scratch the workpiece.

Six, how to monitor and adjust in the cnc processing process?

The workpiece can enter the automatic processing stage after finding and debugging the program. In the process of automatic machining, the operator should monitor the cutting process to prevent the abnormal cutting caused by workpiece quality problems and other accidents.

The following aspects should be considered in monitoring the cutting process:

1, the main consideration of the machining process monitoring rough machining is the rapid removal of the excess of the workpiece surface. In the automatic machining process of machine tool, according to the set cutting parameters, the tool automatically cuts according to the predetermined cutting path. At this time, the operator should pay attention to observe the change of the cutting load in the process of automatic machining through the cutting load table, according to the bearing condition of the tool, adjust the cutting dosage, play the maximum efficiency of the machine tool.

2, monitoring of cutting sound in the process of automatic cutting, generally start cutting, the sound of cutting workpiece is stable, continuous, light, at this time the movement of the machine tool is stable. With the progress of the cutting process, when the workpiece has a hard point or tool wear or tool clip and other reasons, the cutting process is unstable, unstable performance is the cutting sound change, the tool and the workpiece will collide with each other, the machine will appear vibration. At this time should timely adjust the cutting parameters and cutting conditions, when the adjustment effect is not obvious, should suspend the machine tool, check the condition of the tool and the workpiece.

3, finishing process monitoring finishing, mainly to ensure the workpiece processing size and processing surface quality, high cutting speed, large feed. At this time, attention should be paid to the impact of debris accumulation on the surface of the processing, for cavity processing, should also pay attention to the corner processing and letting the knife. To solve the above problems, one is to pay attention to adjust the spray position of cutting fluid, so that the machining surface is always in cooling conditions; The second is to pay attention to observe the workpiece has been processed surface quality, by adjusting the cutting parameters, as far as possible to avoid quality changes. If the adjustment still has no obvious effect, it should stop to check whether the original program is reasonable. In particular, pay attention to the position of the tool when suspending or stopping the inspection. If the tool stops in the cutting process, the sudden spindle stops, the workpiece surface will produce the tool mark. Stop should be considered when the tool leaves the cutting state.

4, tool monitoring tool quality largely determines the quality of the workpiece processing. In the process of automatic machining cutting, it is necessary to judge the normal wear condition and abnormal damage condition of the tool through sound monitoring, cutting time control, suspension inspection in the process of cutting, workpiece surface analysis and other methods. According to the processing requirements, timely processing of the tool, to prevent the occurrence of processing quality problems caused by the tool is not timely processing.

Seven, how to choose a reasonable processing tool? How many factors are there in cutting? How many materials do you have? How to determine the tool speed, cutting speed, cutting width?

1, the surface milling should be used to avoid heavy grinding carbide end milling cutter or end milling cutter. General milling, as far as possible to use the second cutting processing, the first time to walk the best end milling cutter rough milling, along the workpiece surface continuous cutting. The recommended width of each cutting tool is 60%- 75% of the diameter of the tool.

2. End milling cutter and end milling cutter with cemented carbide blade are mainly used for machining boss, groove and box mouth surface.

3, ball knife, round knife (also known as round nose knife) is often used for processing curved surface and variable bevel contour. The ball knife is used for semi-finishing and finishing. Round knives with carbide inserts are used for rough cutting.

Eight, processing program single what function? What should be included in the process list?

1, processing program is one of the content of CNC machining process design, but also the need for the operator to abide by, execute the procedures, is the specific description of the processing program, the purpose is to let the operator clear the content of the program, clamping and positioning, each processing program selected tools should pay attention to the problem.

2, in the processing program, should include: drawing and programming file name, the name of the workpiece, clamping sketch, program name, each program used by the tool, the maximum depth of cutting, processing properties (such as rough machining or fine machining), theoretical processing time, etc.

9. What should I do before NC programming?

After determining the processing technology, understand before programming:

1. Workpiece clamping method;

2, the size of the workpiece hair embryo ---- in order to determine the scope of processing or whether the need for multiple clamping;

3, the workpiece material ---- in order to choose the processing tool used;

4, the inventory of the knife ---- to avoid in processing because there is no tool to modify the procedure, if you must use the tool, you can prepare in advance.

Ten, what are the principles of setting the safe height in programming?

Safe altitude setting principle: generally above the highest side of the island. Or the programming zero set in the highest surface, which can also maximize the risk of knife collision.

11. After the tool path is compiled, why should post-processing be carried out?

Because different machine tools can recognize the address code and NC program format is different, so we should choose the correct post-processing format for the machine tool used in order to ensure that the program can run.

12. What is DNC Communication?

Program conveying method can be divided into CNC and DNC two kinds, CNC refers to the program through the media media (such as floppy disk, reading tape machine, communication line, etc.) transported to the machine memory storage, processing from the memory out of the program to process. Because the capacity of the memory is limited by the size, so when the program is large, DNC can be used for processing, because the DNC processing machine tool directly from the control computer to read the program (that is, to do while sending), so the capacity of the memory is not limited by the size.

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

2, according to the material classification, the tool is generally divided into ordinary hard white steel knife (material for high speed steel), coating tool (such as titanium plating, etc.), alloy tool (such as tungsten steel, boron nitride tool, etc.).