What is CNC Turning? Plus 3 Things You Need to Know About It

by | Jul 31, 2021 | CNC Machining, Manufacturing Processes

If you are looking to learn about CNC turning, you’ve come to the right place.

CNC turning is a CNC process where a cutting tool, a typically non-rotating component of the lathe or turning center, removes material from a rotating rigid material. This process produces different shapes and sizes depending on the turning operations used.

A straightforward concept, yes, but high-quality CNC turning is somewhat more complex. You may be wondering what a lathe or turning center is? What shapes can you make by this manufacturing process? What do you need for CNC turning to be successful? Or even what CNC stands for?

This blog will answer all these questions for you, and reading it will help you understand if CNC turning is the right manufacturing process for you!

What is CNC Turning?

What is CNC turning? Here is the inside of a CNC turning center

Inside a CNC turning center

The first part of CNC turning is “CNC,” which stands for “computer numerical control” and is commonly associated with the automation of machining processes.

“Turning” is the machining term for a process where the workpiece is rotated while a single-point cutting tool removes material to match the final part design.

Therefore, CNC turning is an industrial machining process controlled by a computer and carried out on equipment capable of turning: a lathe or a turning center.  This process can take place with the axis of rotation in the horizontal or vertical orientation. The latter being used primarily for workpieces with a large radius relative to their length.

#1 What Shapes Can CNC Turning Make?

What is CNC turning? Here is an example of turned parts

Various parts made by CNC turning

Turning is a highly versatile machining process capable of making a wide range of profiles depending on the turning process used. The functionality of lathes and turning centers allows for straight turning, taper turning, external grooving, threading, knurling, boring, and drilling.

Generally, lathes are limited to simpler turning operations, like straight turning, external grooving, threading, and boring operations. The tool turret on turning centers allows the turning center to complete all the operations of a lathe as well as more complex operations, such as drilling off the axis of rotation.

CNC turning can produce a wide range of shapes with axial symmetry, like cones, cylinders, disks, or a combination of those shapes. Some turning centers are even capable of polygonal turning, using special rotating tools to create shapes like a hexagon along the axis of rotation.

Although the workpiece is generally the only object rotating, the cutting tool can move too! Tooling can move on 1, 2, or even up to 5 axes to produce precision shapes. Now, you can imagine all the shapes you can achieve using a block of metal, wood, or plastic.

CNC turning is a widespread manufacturing method, so it isn’t hard to spot some everyday objects we use that are manufactured using this process. Even the device you are using to read this blog has screws or bolts and nuts produced by a CNC turning machine, not to mention applications as advanced as aerospace or automotive parts. But, how are all those made?

#2 What Do You Need to Make A CNC Turned Part?

CNC turned part

A CNC turned part

Though this is a complex process, we will simplify it for you with just three simple ingredients: the design of the piece, the cutting speed-to-feed ratio, and the raw material. So, let’s start!

The Design of Your Piece

The very first step is to translate your design into the CNC turning machine language. No worries, we are not talking about advanced programming. Probably, you have already made some drawings of your design. Great! You may want to consider capturing those designs electronically in software like AutoCAD or SolidWorks.

Once you have your electronic design, it is a piece of cake! You only need to convert your drawing, saved as a CAD file by default, into the proper format, the CAM file. Actually, software tools such as AutoCAD and SolidWorks can export the drawing with this format using the “export as” option.

Cutting Speed vs. Feed Rate

Now comes the action! In the turning process, there are two variables you need to keep in mind. The first is the turning speed, which is the velocity of the rotation of the workpiece. The second is the feed rate, which is the velocity at which the cutting tool moves along the rotating workpiece.

These values must be determined by an expert as improper estimations will affect your results, and with some materials, this could cause an uneven finish or irreparable damage to the workpiece.

That said, lower turning speeds and a higher feed rate are generally used for “roughing” out the shape. Then a high turning speed combined with a lower feed rate is used to create a smooth finish and to create parts that meet precise tolerance requirements.

Raw Material

The raw material is a crucial ingredient! Undoubtedly, the type of material used determines the properties of the resulting part. The same piece obtained from wood, plastic, or metal will differ in functionality and even the roughness or smoothness of the finished surface. For more information on the types of materials you can use, check out our blog post on materials for CNC machining.

The size, weight, and shape of the workpiece are also critical because they affect the balance of the workpiece and the size of the lathe or turning center required. An unbalanced workpiece will not create precise final results!

#3 Should You Use CNC Turning?

Gensun technicians operating CNC turning centers

Gensun technicians operating CNC turning centers

CNC turning is a cornerstone in the manufacturing industry. If your design is axially symmetric, this could be the right manufacturing process for you to create precision parts, either for mass production or in small batches.

Nevertheless, if you feel that your designed parts are too large, heavy, non-symmetrical, or have other complex geometries, you may want to consider another manufacturing process, such as CNC milling or 3D printing.

If, however, you are considering using CNC turning, you should check out our turning services page or reach out to one of our service experts to learn more about your options for products manufactured by our efficient, high-precision CNC turning process!

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