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What is CNC turning?

Learn all about the subtractive manufacturing process of CNC turning. This article explores how CNC turning machines work, what kinds of parts you can produce with turning, and tips that result in CNC turned parts that function effectively.

What is CNC turning?

CNC turning is a machining process in which a rotating workpiece is held in a chuck or collet while cutting tools remove material to create the desired shape. The cutting tools move along multiple axes, determined by a computer numerical control (CNC) system, to perform operations such as turning, facing, threading, and grooving. 

What is the difference between CNC turning and CNC milling?

In the CNC turning process, the workpiece spins around an axis and the machine tool moves in a linear action. This enables cylindrical parts to be produced, as well as operations such as cutting, drilling, turning and threading. It also uses an SPTT or a single-point turning tool that’s in direct contact with the workpiece throughout the operation. 

Conversely, in CNC milling, the cutting tool spins around an axis and the workpiece moves linearly, which generates a flat surface, usually used to machine rectangular shapes. Unlike turning, the milling process relies on intermittent cutting and multiple machine steps. 


How do CNC turning machines work?

Here is a brief rundown of the CNC turning process:

  • Workpiece setup. The workpiece (the object or material being machined or worked on) is securely mounted onto the machine's chuck or collet, which holds it in place for rotation during the machining process. This ensures stability and allows for precise cutting.

  • Tool selection. Cutting tools, tailored to the specific machining operations, are selected and loaded into the machine's turret or toolholder. The tools may include turning tools, grooving tools, threading tools, or drilling tools.

  • Machining operations. The machine executes the programmed instructions, with the spindle rotating the workpiece while the cutting tools move along their respective axes. This process removes material from the workpiece, shaping it to the desired dimensions and features. 

What kind of parts can you make with CNC turning machines?

CNC turning machines are versatile tools capable of producing a wide range of parts with varying complexities. Here are some examples of parts that can be made using CNC turning:

  • Bushings and bearings. Precision-made bushings and bearings are vital in mechanical assemblies, reducing friction and supporting smooth rotational movement.

  • Connectors and fittings. CNC turning enables the production of connectors, fittings, and couplings used in plumbing, hydraulic systems, and electrical applications.

  • Fasteners. Screws, bolts, and nuts, produced with CNC turning, are essential components used in assemblies across industries for joining and securing parts.

  • Valves and valve components. CNC turning allows for the creation of valve bodies, stems, seats, and intricate components used in fluid control systems.

  • Tooling components. Such as inserts, toolholders, and bodies used in machining operations, enhancing efficiency and accuracy.

  • Automotive parts. CNC turning is employed to create engine components, pulleys, brackets, and specialized parts for the automotive industry.

How do you design parts for CNC turning?

The following tips and considerations can help you design parts that are well-suited for CNC turning, resulting in efficient manufacturing and high-quality finished products.

  • Design for rotation. Because CNC turning involves rotating the workpiece, ensure that the part design allows for effective rotation and machining. Avoid complex internal features or shapes that may hinder proper machining access.

  • Simplify geometry. Keep your part’s design as simple as possible to facilitate efficient machining. Minimize the number of features, sharp corners, or complex curves that can increase machining time and complexity.

  • Tool selection. Consider the selection of cutting tools for the machining operations required. Design the part to accommodate standard tool sizes and shapes, minimizing the need for custom or specialized tools.

  • Avoid overhangs and thin sections. To ensure stability and prevent deflection during machining, minimize overhangs and thin sections in the design. Adequate support and rigidity will result in better machining accuracy and surface finish.

Which tool or design works best for which material?

In CNC turning, the choice of tools and designs depends on the specific material being machined. Different materials have unique properties that influence tool selection and cutting strategies. Here are a few common materials used in CNC turning and the recommended tools and designs for each. 

  • Low/medium carbon steel. When machining low to medium carbon steel, you should use carbide inserts with a tougher grade and a positive rake angle. Additionally, use sturdy toolholders, adequate coolant and lubrication, and a slower cutting speed compared to aluminum.

Fast CNC turning with local machine shops

Protolabs Network's network of local machine shops in the US and EU makes it easier to get CNC turned parts quickly. Local manufacturing eliminates the need for your parts to clear customs, so you benefit from fewer logistical hurdles and lead times as fast as five days. 

Use Protolabs Network's CNC turning service

Find out more about Protolabs Network's CNC turning capabilities.  When you’re ready to get an instant quote for a custom part, upload a CAD file and select CNC turning as the service.

You can also read more about different types of CNC machining, including advice on material selection, surface finishes and optimizing your design. 

CNC machining, 3D printing and sheet metal fabrication parts

Frequently asked questions

What materials can be used in CNC turning?

CNC turning can work with a variety of materials, including metals like aluminum, steel, brass, and titanium, as well as plastics such as acrylic, nylon, and polycarbonate.

What are the advantages of CNC turning?

CNC turning offers benefits such as high precision, repeatability, versatility for complex shapes, shorter production cycles, and the ability to work with both small and large quantities of parts.

What are the typical applications of CNC turning?

CNC turning is commonly used in industries such as automotive, aerospace, electronics, medical devices, and general manufacturing for producing parts like shafts, bushings, connectors, valves, and fasteners.

How long does a typical CNC turning process take?

The time required for CNC turning depends on factors like the complexity of the part, material type, tolerances, and the machining operations involved, but it can range from minutes to hours. For time-sensitive projects, select the local manufacturing option with lead times from 5 days. 

Is CNC turning suitable for prototypes or large-scale production?

CNC turning is suitable for both prototypes and large-scale production. It offers cost-effective production for large quantities, while also allowing for efficient machining of prototypes with quick setup and programming adjustments.

Is CNC turning expensive?

The cost of CNC turning can vary depending on factors such as part complexity, material selection, machine setup, and volume of production, making it difficult to provide a definitive answer without specific details. Protolabs Network's online quote builder reveals pricing in seconds. 


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