Some common problems we may have in CNC and How we can improve them

Have your CNC machines been behaving oddly lately? Do you notice a strange tick in their output, or in the way the machines are acting? If so, you’re in the right place. We’re going to talk about a few of the most common problems in CNC machines, and how to fix these problems.

A. Workpiece overcut


a. Bounce the knife, the strength of the knife is not long enough or too small, causing the knife to bounce.

b. Improper operation by the operator.

3. Uneven cutting allowance (eg: 0.5 on the side of the curved surface and 0.15 on the bottom)

4. Improper cutting parameters (such as: tolerance too large, SF setting too fast, etc.)


a. The principle of using knives: rather big than small, and rather short than long.

b. Add a corner cleaning program, and keep the margin as uniform as possible (the side and bottom margins should be the same).

c. Reasonably adjust the cutting parameters, and round the corners with large allowance.

d. Using the SF function of the machine, the operator can fine-tune the speed to achieve the best cutting effect of the machine tool.

B. Cutting Tools setting problem


a. Not accurate when manually operated by the operator.

b. The clamping tool is set incorrectly.

c. There is an error in the blade on the flying knife (the flying knife itself has a certain error).

d. There is an error between the R knife and the flat bottom knife and the flying knife.


a. Manual operation should be carefully checked repeatedly, and the knife should be set at the same point as much as possible.

b. Use an air gun to clean the tool or wipe it with a rag when clamping.

c. One blade can be used when the blade on the flying knife needs to measure the shank and smooth bottom surface.

d. A separate tool setting program can avoid the error between the R tool, the flat tool and the flying tool.

C. Curved Surface accuracy


a. The cutting parameters are unreasonable, and then the curved surface of the workpiece is rough.

b. The cutting edge of the tool is not sharp.

c. The tool clamping is too long, and the blade avoidance is too long.

d. Chip removal, air blowing, and oil flushing are not good.

e. Programming tool way is not appropriate, (we can try the down milling).

f. The workpiece has burrs.


a. The cutting parameters, tolerances, allowances, and speed feed settings should be reasonable.

b. The tool requires the operator to check and change from time to time.

c. When clamping the tool, the operator is required to clamp it as short as possible, and the blade should not be too long to avoid the air.

d. For the lower cutting of flat knife, R knife and round nose knife, the speed and feed setting should be reasonable.

e. The workpiece has burrs: it is directly related to our machine tool, cutting tool and cutting method. Therefore, we need to understand the performance of the machine tool and make up for the edge with burrs. 

Above are some commen problems we may have in CNC, for more information welcome to contact us to discuss or inquiry. 

Post time: Jun-15-2022