Two Basic Types of CNC Turning Operations

April 7, 2015

CNC turning services have two basic types of operations: external and internal operations. The outer parts of the work piece are fixed through external operations, while the internal operations focus on the inner diameter of the work piece. The two basic operations have different classifications.



external operations

1. Turning

Turning is considered as the most basic process of operation. In this process, the work piece is turned or rotated on the axis of a cutting tool. After turning, the work piece will have a more defined finish and a specific target diameter will be reached.  The turning process includes:

  • Tapered turning
  • Spherical generation
  • Hard turning

2. Facing

Unlike turning, the cutting tool in this type of operation moves radially down the end of the work piece. It is effective to use even on a very small depth of material. Facing usually removes the thin excess of the work piece to perfectly shape the edges.

3. Parting

In this operation, a cutting tool moves radially to reach a certain diameter required for the work piece. The tool is basically cutting off a section in the centre of the material. This operation is also known as “cut-off”.

4. Thread Cutting

The threading operation uses a tool that usually has a 55 to 60 degree nose angle. This tool moves axially on the outer surface of the work piece. The thread requires multiple movement to form the desired length of the work piece.



internal operations

1. Drilling

A drilling tool is used to make a hole in the centre of the work piece. The tool moves axially and is available in different sizes to obtain a specific central diameter of the material.

2. Boring

Unlike drilling, boring tools are adjustable based on the required diameter of the work piece. It is inserted in the centre of the work piece to achieve different features including tapers, contours, steps and chamfers.

3. Tapping

Tapping is done in an existing hole made by a driller or a boring tool. This process is also considered as internal threading.


Are you looking for high quality CNC turning services? HPC Services Ltd. is the right provider for you. We offer external and internal operations for your turning needs. Contact us on 0115 932 3773 for more information.