How to avoid bumping in CNC machining?

In the process of CNC machining, one of the most important points is that when programming (procedure) and operating processing, the CNC processing center must be avoided bumping. Because the price of CNC machining center is very expensive, the repair is difficult and expensive. However, the occurrence of bumping is a certain rule to follow and can be avoided, mainly the following points.            

1. Using computer simulation (copy) simulation system            

With the development of computer technology and the continuous expansion of NC machining education, more and more simulation systems for NC machining simulation have been developed, and their functions are becoming more and more perfect. Therefore, it can be used to start viewing the program and observe the movement of the tool to determine whether it is possible to knock.

2. Making use of the function of imitation display in CNC machining center           

Generally more advanced CNC machining centers have graphics display function. When the program is input, the graphics simulation display function can be invoked to observe the movement track of the tool (called track) in detail, so as to see whether the tool and the workpiece or fixture are likely to bump.  

3. Utilizing the empty operation function of CNC machining center            

Using the empty running function of CNC machining center, we can check whether the tool path is correct or not. When the program is input into CNC machining center, the tool or workpiece can be installed, and then the button is pressed. At this moment, the spindle does not rotate, and the worktable runs actively according to the program track. At this moment, it can be found whether the tool is likely to collide with the workpiece or fixture. However, in this case, it is necessary to ensure that the cutter can not be installed when the workpiece is installed; when the cutter is installed, the workpiece can not be installed, or there will be knocks.    


 4. Using Lock Function of CNC Machining Center            
General CNC machining centers have locking function (full lock or single shaft lock). When the program is input, the Z-axis can be locked, and the coordinate value of the Z-axis can be used to determine whether the collision will occur. The use of this function should avoid the operation of tool change, or the program can not pass through.   

5. It is necessary to set up the coordinate system and cutter compensation correctly.            

When starting a CNC machining center, the reference point of CNC machining center must be set. The working coordinate system of CNC machining center should be consistent with programming, especially Z axis direction. If mistakes are made, the possibility of milling cutter colliding with workpiece is very large. In addition, the settings of tool length compensation need to be correct, otherwise, either empty processing or bumping.       

6. Improving Programming Skills            

Programming is an important part of NC machining. Improving programming skills can largely avoid unnecessary collisions.            
For example, when milling is completed, the milling cutter is required to return quickly to 100 mm above the workpiece. If the CNC machining center is programmed with N50 G00 X0 Y0 Z100, the three-axis linkage will occur, and the milling cutter may collide with the workpiece, causing damage between the cutter and the workpiece, seriously affecting the accuracy of the CNC machining center. The following stroke can be used. Sequence N40 G00 Z100; N50 X0 Y0; that is, the tool first returns to 100 mm above the workpiece, and then returns to programming zero, so that it will not bump.  

In a word, mastering the programming skills of CNC machining centers can improve the processing efficiency and quality, and avoid unnecessary faults in processing. This requires us to constantly sum up experience in practice and constantly improve, so that programming and processing capabilities can be further strengthened and improved. 

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