CNC machining is controlled by computer after programming, which gives its benefits of stable machining quality, high machining accuracy and efficiency, repeatability, etc. But the actual processing needs to go through many stages to get the final CNC machined parts. How to ensure the best processing quality? Here are some tips for CNC machining, featuring CNC tool path selection, coordinate system and CNC production monitoring and optimization.

How to Choose the CNC Tool Path?

Tool path refers to the path and direction of the cutting tool tip relative to the workpiece follows on its way in the CNC machining process, through coordinate locations, to produce machined parts with desired geometry. The choice of toolpath is important because it is closely related to the machining accuracy and surface quality of workpiece. Tips for determining the CNC tool path:

1. Ensure the machining accuracy of parts.

2. Reduce CNC programming workload.

3. Seek the shortest processing route, reduce the time of empty cutting to improve efficiency.

4. Minimize the number of programs segments.

5. Ensure the roughness after workpiece contour surface machining. The final contour shall be processed continuously by the last tool.

6. The feed and retract paths of the tool should also be carefully considered to minimize the tool marks caused by stopping at the contour, and to avoid cutting vertically on the contour surface and scratching the workpiece. 

CNC Coordinate System 

Machine coordinate system is the motion physical limits of the machine in each of its axes,the numerical coordinate is assigned to each of these limits. The origin of the workpiece coordinate system is set by the operator. 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 determined, it is generally not changed. During the machining process, the workpiece coordinate system and the programming coordinate system must be consistent. 

How to Monitor and Adjust During Processing? - CNC Production Monitoring and Optimization

After tool setting, path selection, CNC machining programming and more preparations, the automatic processing can get started. But in the process, the operator should pay attention to and monitor each stage of the cutting and machining, to avoid any problems. Here are several considerations for operators:

1. The main consideration of rough machining is the rapid removal of the surplus on the workpiece surface. The operator should observe the change of cutting load in the automatic machining process through the cutting load table, adjust the cutting parameters according to the bearing force of the cutter, to achieve the maximum efficiency of machine tool.

2. Machining sound and noise. At the beginning of cutting, the sound of the tool cutting the workpiece is stable, continuous and light, and the movement of the machine tool is stable. As the cutting process continues, when there are Hard Spots on the workpiece, tool wear or other reasons make the cutting process unstable. Then the machining sound changes, the tool and the workpiece will collide with each other, and the machine tool will vibrate. At this time, the cutting parameters and cutting conditions shall be adjusted in time. If the phenomenon is not improved, stop the machine and check the condition of tools and workpieces.

3. Finish machining is mainly to ensure the machining dimensions and surface quality of the workpiece, with high cutting speed and large feed. At this time, we should pay more attention to the effect of chip accretion on the machined surface. First, adjust the spray position of the cutting fluid to keep the machining surface in cooling condition at all times; second, observe the quality of the machined surface of the workpiece, adjust the cutting parameters when there is a problem, and stop the machine to check whether the original program is reasonable. Note: when the machine is suspended or stopped for inspection, the tool shouldn’t in cutting. If the machine stops in the cutting process and the spindle stops suddenly, the surface of the workpiece will leave tool marks.

4. The quality of cutting tool greatly affects the parts quality, analyze the tool wear, handle the problem and change the tool properly when necessary.