Turning Defects and Causes
Turning is one of the most common machining processes and is also one of the most efficient ways to produce precision parts. It is used to produce cylindrical surfaces, external threads and internal threads, grooves, and other features. Turning requires a tool to be mounted on a rotating spindle, providing the necessary cutting force to the material.
Although the turning process is quite simple, it still has its own set of defects which can arise during the machining process. These defects can either be caused by incorrect machine operation or incorrect tooling selection, or even the quality of the raw material itself. Let’s have a look at some of the common defects and their causes.
Chip Breaks:
One of the most common turning defects is chip breakage. This occurs when the chip created during the cutting process breaks into pieces mid-air and eventually damages the surface of the component. This is usually caused by excessive stress on the tool due to inadequate tooling, insufficient cutting fluid, inappropriate cutting speed, or excessive feed rates.
Scratches:
Scratches occur when the cutting tool slides across the surface of the component, leaving an undesirable mark on it. This most often happens when feed forces are too high and cause the tool to slide when cutting. This can be caused due to incorrect tool selection, incorrect settings of the cutting speed, improper tool settings, or inadequate chip breakage.
Broken Tools:
Broken tools can also be a result of defective turning. This happens when the cutting forces are too high, leading to the cracking or breaking of the cutting tool. This is usually caused by too low of a cutting speed, excessive feed rates, and improper tool selection, or inadequate cutting fluid.
Dimensional Errors: Dimensional errors are one of the more common defects in turning. This happens when the component does not meet the desired specifications and tolerances. This is usually caused due to incorrect settings of the cutting speed and feed rate, incorrect tool selection, improper chip breakage, or inadequate coolant flow.
Poor Surface Finish:
The surface finish of the component is an important factor when it comes to turning. Poor surface finish is usually caused by overworking the part with too high of a cutting speed, tools that are too dull, and improper chip breakage, or inadequate cutting fluid.
Conclusion:
All of the aforementioned issues are quite common when it comes to turning, and can be caused by numerous different factors. To prevent any of these defects, it is important to ensure that the correct tooling is selected, that cutting speeds and feed rates are set correctly, and that adequate coolant and chip breakage are maintained. If these issues are addressed and corrected, successful turning with minimal defects should be achieved.
