Identifying Common CNC Machining Defects and Control Measures

June 11, 2020

A lot of industries are now utilising CNC machining since it only reduces manual labour works and overall costs. This process also produces precise, high-quality products under a short time, which makes it more efficient than its manual counterparts. This efficiency even extends to the fact that CNC machining can be used in different applications.

However, just like any other machine, it can still encounter defects and errors along the way. The following are some problems that you may encounter with CNC machining, as well as the necessary control measures that you can implement.

Tool Misalignment

A CNC machining can occur whenever the tool is misaligned. One sign of this defect is the presence of incorrect shape or geometry in machined components. Having dimensions that are beyond tolerance limits is also a clear sign of this problem. As a control measure, you must properly mount the tool to the machine. You must also check the alignment of the chuck, tailstock, and tool before starting the CNC operations.

Improper Clamping

Improper clamping of the workpiece often results in poor surface finish and even damage to tool holder and insert. Increased vibrations between the workpiece and the cutting tool are also prevalent when the workpiece is not clamped properly. To avoid this problem from happening, you must make sure that the hydraulic pump and the foot switch is running. You must also check if the workpiece is aligned properly alongside the rotating axis and the cutting tool axis.

Chatter Error

Chatter is a situation where the machine or workpiece vibrates uncontrollably. This happens when you set up the machine poorly. Installing your insert badly can also cause this type of error. Any errors due to chatter can significantly damage your tool and your machine due to violent vibrations. The service life of your tool and machine can also be reduced due to chatter error. To control chatter, you must either reduce or increase the feed rate. You must also use more positive chip breakers.

Poor Surface Finish

Having a poor surface finish on your workpiece can turn off a lot of clients. This happens when your feed rate is too great for the nose radius. Working with low cutting speed and poor shearing action can also contribute to the poor surface finish problem. For control purposes, you must reduce the feed rate and increase cutting speed until you get the perfect surface finish. The use of larger nose radius inserts and a more positive chip breaker is also recommended to produce the optimal surface finish.

Burning of Material

The burning of the material of your workpiece can be caused by numerous reasons. Your tool may be already blunt or that your feed speed is too slow. Putting the tool in the wrong spindle or operating at incorrect spindle speed can also burn your material. Some control measures that you can do to avoid this problem include replacing the sharp tool, changing the spindle speed, changing the feed speed, and inserting a tool in the correct spindle.

These common CNC machining defects can easily be solved if you know their main roots and subsequently follow control measures. If you want to know more about CNC machining defects, feel free to call us at Gunna Engineering.

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