Types of CNC Turning Operations: Back to Basics

In a CNC machine, cutting tools driven by computer software cuts away the excess material to get the expected product. The cutting tool takes a helical path which can move more or less linearly when the workpiece rotates.

The turning operations are basically divided into two types:

1. Internal machining operations

2. External machining operations

Internal machining operations


It is the most basic operation of CNC machine, in this process, the workpiece is rotated along the axis of the cutting tool, which gives it an expected finish.

Turning composes:

Tapering turning

It mainly produces a conical surface by increasing or decreasing the diameter of cylindrical piece.

CNC machines require high precision CNC component for accurate cutting and to meet industry standards.

Spherical and hard turning

Spherical turning produces a ball shape of the component, hard turning, on the other hand is done to provide roundness accuracy to a work piece after its being heated. It has several applications among which some of them are gears, injection and hydraulic components.


Facing involves the rotation of the cutting tool with the right angle of the axis of rotation of the workpiece.

Parting and grooving

In parting a complete part or a part is removed from the parent stock. Grooving is similar to the parting except that a specific depth is cut not the whole part or a part of the component.

External machining operations


It is the process of enlarging the hole which is already being cast or drilled.

Boring is used to achieve accuracy by altering the diameter of the hole. The tools used for boring are adjustable based on the required diameter of the component.


Drilling is the process of completely removing the material from the inside of the workpiece.

Different sizes of the tools are available to produce the specific drilling results. This process can also be done with separate drilling tools.


In reaming a small amount of metal is cut from a hole which is already being drilled. It is used for making internal holes of very accurate dimension.


Standard and nonstandard threads are produced using appropriate cutting tools.

This is generally called single point threading, the shape or form of the thread depends upon the mounting position of the cutting tool.

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