What is machine turning?

Manufacturing companies use dozens of machining processes to create products from raw and semi-finished materials. One of the most common processes is machine turning.

In this article, our precision machining specialists will provide a wealth of information about this machining technique.

A brief definition of machine turning

Like other machining processes, turning is a process that involves removing material. During the process, a machine removes excess material from a rotating part with a cutting tool.

The workpiece rotates, held by a chuck or collet, while the cutting tool moves linearly. The combination of the two movements removes material in the form of chips. The speed of these movements can be adjusted to obtain the desired results.

Machine turning is a very effective technique for manufacturing pieces from various materials such as steel, aluminum, copper, zinc, and even wood and plastic.

Machine turning is commonly used as a secondary process to add or refine features on pieces that have already been manufactured using another machining process. Due to the high tolerance and surface finish turning offers, it is an ideal process for adding precise features to a workpiece that has already been shaped.

Equipment needed for machine turning

The machine turning process requires a lathe or turning machine, a workpiece, a workholding device and a cutting tool.

The workpiece is a pre-shaped piece of material that is held by the workholding device, which is attached to the lathe and can turn at high speed. The cutting tool is usually a single-point high-speed steel (HSS) or carbide tool that is also attached to the turning machine, although some processes use multipoint tools.

Manual vs. CNC lathes

Turning can be manual or automated. The disadvantage of working with a manual lathe is that it requires continuous supervision, while automated turning does not. With computer numerical control, or CNC, you can program all cutting tool changes, movements and speeds into a computer, which will then send the instructions to the lathe.

Types of machine turning operations

During the machine turning process, various operations can be performed to give the workpiece the desired shape. The operations can be categorized as external or internal. External operations change the outside of the workpiece, while internal operations modify the inside.

The following operations are differentiated by the type of cutting tool used and its trajectory.

External turning operations

Turning

A single-point cutting tool moves axially along the workpiece, removing material to make features such as notches, cones, chamfers and contours. The features are generally machined at a shallow radial depth and multiple passes are made to reach the desired diameter.

Facing

A single-point cutting tool moves radially across the end of the workpiece, removing a thin layer of material to obtain a smooth, flat surface. The depth of the face, which is usually very small, can be machined in a single pass or can be achieved by machining at a smaller axial cutting depth and performing multiple passes.

Grooving

A single-point cutting tool moves radially across the side of the workpiece, cutting a groove the same width as the cutting tool. Multiple cuts can be made to form a groove wider than the cutting tool, and specially-shaped cutting tools can be used to create different geometric shapes.

Parting

A single-point cutting tool moves radially across the side of the workpiece, continuing until it reaches the centre or interior diameter of the piece, cutting it in two.

Threading

A single-point cutting tool, usually with a cutting angle of 60 degrees, moves axially along the side of the workpiece, cutting threads in the outer surface. The threads can be cut to specific lengths and pitches and may require multiple passes to create.

Internal turning operations

Drilling

A drill bit enters the workpiece from one end and creates a hole with a diameter equal to its own.

Boring

A cutting tool penetrates axially into the workpiece and removes material along the inner surface to create features such as notches, cones, chamfers and contours.

The boring tool is usually a single-point cutting tool that can be adjusted to create the desired diameter due to an adjustable boring head. Boring is generally done after a hole has been created in order to increase the diameter or obtain more precise dimensions.

Tapping

A cutting tool penetrates axially into the workpiece from the end and creates internal threads in an existing hole.

Machine turning training

In Quebec, anyone who wants to become a machinist and learn how to perform machine turning operations can enroll in a Diploma of Vocational Studies (DVS, or DEP in French) in Machining Techniques. This 1,800-hour program is offered in a large number of educational institutions across the province.

The basics of mechanical turning can also be learned as part of an Attestation of College Studies (ACS, or AEC in French) in mechanical manufacturing, which lasts 1,725 hours.

Trust Braidwood Industries Ltd. with your machine turning needs

We hope you were able to find the information you were looking for in this text.

If you would like more information about machine turning, contact our experienced machinists. At Braidwood Industries Ltd., we use machine turning regularly to create specialized pieces such as custom gears.

About the Author: yohan