What is the Difference Between CNC Milling and CNC Turning?

  • Updated: June 25, 2024

About the Authors

Frank Lee

At the helm of XMAKE, Lee directs the vision with expertise honed at HIT with over 16 years in the field, including as a Lean Manufacturing System expert at General Motors and global evaluator, Frank has a proven track record of pioneering improvements across 1000 factories.
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I. Introduction of CNC Turning and Milling

Find out the small but important differences between CNC (computer numerical control) turning and CNC milling, which are two of the most important tools in the precision making. CNC milling is like sculpting in that it chips away material to show the shape that is wanted. CNC turning, on the other hand, shapes cylinders with rotation accuracy and is similar to making pottery on a wheel. Understanding these differences is important for picking the right tool for your industrial needs and making sure that everything is done well and efficiently.

II. What is CNC Milling?

XMAKE CNC Milling machine

Definition of CNC Milling

CNC milling is a subtractive manufacturing process where the material is removed from a workpiece to create a part with specific dimensions and features.  Utilizing Computer Numerical Control, this technology allows for the automation of milling s, which follows pre-programmed instructions to achieve high precision and repeatability in part production.

 How CNC Milling Works

In CNC milling, a workpiece is secured on a bed, and multiple cutting tools are used to remove material.  The tools, guided by the spindle, move in various directions—X, Y, and Z axes—to shape the workpiece.  The process is controlled by software that converts 3D models into a series of -readable commands, ensuring exact replication of the design.

 Types of Processes and Operations Involved in CNC Milling

CNC milling encompasses a variety of processes, including 2D and 3D machining, drilling, boring, and slotting.  Each operation is selected based on the desired shape and features of the final part.  For instance, 3D machining creates complex geometrical shapes, while drilling is used to produce holes.  The choice of operation depends on the material, design specifications, and the required precision.

 Benefits of CNC Milling

CNC milling offers several advantages, making it a preferred choice for manufacturing complex parts.  It provides high precision and accuracy, allowing for the production of parts with tight tolerances.  The process is efficient, reducing production time and labor costs.  Additionally, it offers design flexibility, as it can handle a wide range of materials and intricate designs.  The automation aspect of CNC milling also minimizes human error, ensuring consistent quality in every part produced.

III. What is CNC Turning?

XMAKE CNC Turning Machine

 Definition of CNC Turning

CNC turning, a form of subtractive manufacturing, is the process of rotating a workpiece against a stationary cutting tool to achieve the desired shape and dimensions.  This precision technique is ideal for creating cylindrical parts and is controlled by computer software that translates design parameters into motion, ensuring accuracy and repeatability at every turn.

 How CNC Turning Works

In CNC turning, the workpiece is mounted on a lathe which spins at high speeds while the cutting tool, guided by the computer, moves along the workpiece to remove material.  The tool’s path is carefully calculated to follow the exact dimensions specified in the part design, resulting in a high-quality finish on the exterior or interior surfaces of cylindrical components.

 Types of Processes and Operations Involved in CNC Turning

CNC turning encompasses a range of operations, such as turning, boring, threading, taper turning, and chamfering.  Each process is meticulously chosen to achieve specific features of the part.  For example, turning is used to create the main cylindrical shape, while threading is applied to produce helical features, making CNC turning a versatile choice for various part designs.

 Advantages of CNC Turning

CNC turning offers numerous benefits, including high precision and surface finish quality, which are essential for close-tolerance parts.  Its automated nature leads to increased efficiency and reduced labor costs.  The process is suitable for a wide range of materials, from soft plastics to hard metals, and is capable of producing complex geometries.  Furthermore, CNC turning allows for quick setup and changeover, making it ideal for both prototype development and mass production.

IV. Key Differences Between CNC Milling and Turning

XMAKE cnc turning& cnc milling

CNC milling shapes parts via rotating tools on a stationary workpiece, while CNC turning creates cylindrical parts by rotating the workpiece against stationary tools. CNC Milling and CNC Turning differ in several key ways:

1. Machining Principle:

CNC Milling: a rotating tool is used to cut material that is fixed to a table, removing material in a variety of ways such as milling, drilling, and engraving.

CNC Turning: The workpiece is mounted on a rotating chuck, and the tool remains relatively stationary or moves along its axis to cut the rotating workpiece, mainly used to manufacture cylindrical or round parts.

2. Workpiece Shape:

CNC Milling: suitable for machining parts with complex geometries, including flat surfaces, beveled surfaces, grooves, and irregular shapes.

CNC Turning: Mainly used for machining symmetrical rotating bodies, such as cylindrical, conical, spherical, and disk.

3. Machining Capacity:

CNC Milling: Capable of multi-axis machining, including 3-axis, 4-axis, and 5-axis machining, for complex three-dimensional shapes.

CNC Turning: Usually limited to two or three-axis machining, but can produce high-precision round parts.

4. Equipment Structure:

CNC Milling: consists of a vertical spindle, a rotary head, and a multi-flute tool, which can be moved in multiple directions.

CNC Turning: consists of a chuck, tailstock, and tool, the workpiece rotates on the chuck, and the tool moves along the axis.

5. Material Application:

CNC Milling: It can process various materials such as metal, plastic, and wood.

CNC Turning: usually used for machining metal and some plastic materials, especially suitable for machining hard materials.

6. Productivity:

CNC Milling: may require more setup time and complex programming, but is suitable for producing parts with complex shapes.

CNC Turning: relatively simple setup, suitable for mass production of round parts, and high productivity.

7. Cost Considerations:

CNC Milling: This may be costly due to complex design and multi-axis machining.

CNC Turning: usually lower cost due to high production efficiency, especially for high volume production.

8. Post-processing requirements:

CNC Milling: Additional grinding or polishing steps may be required to achieve the desired surface quality.

CNC Turning: Higher surface finishes can often be achieved directly, reducing the need for post-processing.

V. How to Choose the Right Machining Process?  Turning or Milling?

Consideration CNC Milling CNC Turning
Part Shape Best for complex shapes, flat, angular, or irregular surfaces. Ideal for symmetrical, round, or cylindrical parts.
Material Suitable for metals, plastics, wood, and more. Typically used for metals and some plastics, good for hard materials.
Tolerances & Finish Capable of tight tolerances and fine finishes with multi-axis control. High precision for round parts, may require less post-processing.
Production Volume Flexible for low to medium volumes due to setup and programming times. Efficient for high-volume production of round parts.
Cost Can be more expensive due to complex designs and multi-axis machining. Generally less costly for high-volume production due to efficiency.
Post-Processing May need additional steps for surface finishing. Often achieves high surface quality directly, reducing post-processing needs.
Equipment Complexity Involves more complex s with multiple moving parts and axes. Relatively simpler s focused on rotational cutting.
Tooling Requires a variety of tools for different operations like milling, drilling, and engraving. Uses single-point tools that move along the workpiece’s axis.
Setup Time Can have longer setup times due to programming and tool changes. Typically quicker setup for round part production.
Versatility High, capable of producing a wide range of part geometries. Moderate, focused on round and symmetrical part production.

VI. Conclusion

In conclusion, the distinction between CNC milling and CNC turning lies in their techniques and applications.  CNC milling uses a rotating tool to shape stationary workpieces, ideal for complex geometries.  CNC turning involves a rotating workpiece and stationary tools, perfect for symmetrical, round parts.  Selecting the appropriate process ensures optimal precision, efficiency, and cost-effectiveness in manufacturing.

FAQs

1. Can CNC milling be used for making round parts?

Yes, but CNC milling is more versatile for complex shapes beyond simple round or cylindrical parts.

2. What is the typical tolerance achievable with CNC turning?

CNC turning can achieve very tight tolerances, often within ±0.001 inches, depending on the and setup.

3. Can CNC turning produce parts with complex geometries?

While CNC turning excels at round parts, it can produce some complex geometries with the use of additional axes or special tooling.

4. What is the impact of CNC milling on production costs?

CNC milling can influence costs due to setup time, tooling, and complexity of the part.      However, it often reduces costs by minimizing manual labor and improving efficiency.

5. How do I choose between CNC milling and CNC turning for my project?

The choice depends on the part’s geometry, material, required tolerances, and production volume. Consult with a machinist or engineer to determine the most suitable process for your specific needs.

 References

1. Leo, G. (2023c, September 22). CNC turning explained: process, operation and advantages. Aria | Online Manufacturing for On-Demand Custom Services. https://www.madearia.com/zh-CN/blog/cnc-turning-explained-process-operations-and-advantages/

2. Acharya, D. (2024g, June 14). CNC milling vs. CNC turning: what’s the difference?. Proleantech | Custom Parts On-Demand Manufacturing. https://proleantech.com/zh-CN/cnc-milling-vs-cnc-turning/

3. Ruisheng Precision Technology Co.. (2022b, December 28). The Distinctive Characteristics of CNC Milling and Turning. https://www.runsom.com/zh-cn/blog/cnc-milling-vs-cnc-turning/

4. CNC Turning Machining. (n.d.). https://etc.ouc.edu.cn/2022/0311/c26276a364580/page.htm

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