Do you want to know the difference between CNC turning and milling? Many customers ask this question when deciding how to approach their project best. Although both processes are vital in manufacturing, they have different functions and unique advantages. I will break down the differences so you can make a more informed decision.
CNC milling (using rotary cutters) and turning (using a cutting tool) are forms of machining. However, they remove materials in different ways. The milling process uses rotary tools to remove material, while the turning process involves rotating a workpiece against a cutting instrument. This difference results in different capabilities and applications.
Let’s now dive deeper into CNC milling and CNC turning.
What is CNC Machining?
Computer Numerical Control (CNC) machining, also known as CNC, allows us to produce parts with high accuracy, consistency, efficiency, and consistency. We use CNC machining to automate a variety of tools, such as lathes and mills.
Understanding CNC Milling
CNC Milling Basics
What is CNC Milling?
CNC milling uses computer-controlled cutters to remove materials from a piece of work. The cutters are moved along several axes (usually three to five) to achieve the desired dimensions and shape. Starting with a solid block of material, we gradually remove layers to create intricate designs and features.
Types of CNC Milling Machines
CNC milling machines are available in different types, each with specific capabilities and tasks.
- Vertical milling machines: These have a spindle axis oriented vertically. They are the most popular type and can be used for many tasks.
- Horizontal Milling Machines： The spindle is horizontal. These machines handle heavy work and larger pieces.
- 5-Axis Milling Machines： These advanced machines can simultaneously move the cutting tool along five axes. They are ideal for producing highly complex and accurate parts.
Components of CNC Milling Machines
Spindle
The spindle of a machine is the part that rotates and holds the cutting tool. Spindles come in different speeds and torques.
Worktable
During the milling operation, the workpiece rests on the work table. The worktable supports and secures material to ensure accuracy and stability. It can move in different directions and align the workpiece with the cutting tool.
Tool Changer
This device automatically switches between different cutting tool types during milling. This feature allows you to do various operations without stopping the machine and manually changing tools.
CNC Milling Techniques
Cutting Processes
End Milling
One of the most common techniques is end milling. It involves removing material from a workpiece using a cutting tool called an end mill. End mills can be cut in different directions, allowing us to create complex 3D shapes, such as slots, contours, and holes.
Face Milling
Face milling is cutting the tool with its face or end. This technique primarily creates a flat, even surface on the workpiece. The cutting tool is rotated perpendicularly to the workpiece’s surface, ensuring a smooth finish.
Selecting the Right Tool and Optimizing It
Selecting the Right-End Mill
It is essential to select a suitable end mill for optimal results. Consider the following factors:
- Material： Use different end mills for different materials, such as steel, aluminum, or plastics.
- Geometry: The shape and angle of the cutting edges affect the cutting efficiency and finish quality.
- Coating: Coatings such as titanium nitride or diamond-like Carbon (DLC) can enhance an instrument’s performance and longevity.
The end mill is carefully selected based on project requirements to ensure efficient and accurate machining.
Tool Path Strategies
Tool path optimization is crucial for increasing efficiency and reducing machining time. Some common tool path strategies are:
- Conventional milling: the cutting tool moves in the opposite direction to the rotation of the workpiece. This method is best suited for rough cuts or more rigid materials.
- Climb milling: The tool moves in the opposite direction to the rotation of the workpiece. This method produces a smoother surface. It is recommended for final passes or softer materials.
- Adaptive clearing: This technique adjusts the tool path to maintain constant cutting forces. It reduces tool wear and improves efficiency.
What is CNC turning?
A CNC turning process involves using a cutting tool to remove material from rotating workpieces. The chuck holds the workpiece, and the tool rotates rapidly along the desired path to shape it.
Components of CNC Turning Machines
Lathe
Lathes are the main machine for CNC turning. They hold the workpiece and rotate it while a cutting instrument shapes it. Depending on your project, lathes are available in different configurations, such as vertical and horizontal.
Chuck
The chuck is an essential component of a CNC lathe. It holds the workpiece securely during the turning process. Chucks are available in three, four, and collet styles.
Tool Holders
Tool holders are devices used to secure cutting tools on a CNC lathe. They are available in different designs that accommodate cutting tools, such as boring bars and drills.
CNC Turning Operations
Face
Facing is the basic CNC turning operation in which the cutting tool moves perpendicularly to the axis of the rotating workpiece. The primary purpose of facing is to create a flat end surface.
Grooving
Grooving is cutting a narrow groove or channel into the workpiece. The operation uses a particular grooving device that cuts grooves with specific depths and widths.
Threading
Threading is the turning process in which the cutting tool moves across the workpiece to create threads or helical grooves. This method creates both internal and exterior threads on cylindrical components.
CNC Milling and Turning: Pros and Cons
Precision and Accuracy
CNC Milling
- Pros: CNC milling is excellent for creating intricate and highly detailed parts.
- Cons: Milling complex parts can take a long time.
CNC Turning
- Pros: CNC turning is accurate and suitable for symmetrical and cylindrical parts.
- Cons: Only cylindrical parts can be turned.
Speed and efficiency
CNC Milling
- Pros: Milling is a versatile tool that can perform many tasks without moving the workpiece. Modern CNC mills have automatic tool changers that can change tools quickly and reduce downtime.
- Cons: Milling complex parts can take longer due to multiple passes and settings.
CNC Turning
- Pros: When manufacturing cylindrical parts, it is possible to do this in one setup.
- Cons: Inefficiency of turning drops for non-cylindrical components or multiple features.
Material Compatibility
CNC Milling
- Pros: Milling machines are capable of handling a variety of materials, including metals and plastics.
- Cons: Some more complex materials can wear out milling tools faster, increasing maintenance and tool replacement costs.
CNC Turning
- Pros: Turning works with many materials, including metals.
- Cons: Some materials, such as composites and brittle plastics, may not be suitable for turning because of the risk of cracking.
CNC Milling and Turning: What are the differences?
When choosing the proper machining method for your project, it is essential to understand the differences between milling and turning. Let’s look at the main differences.
- Operation: Milling uses a rotating tool and a stationary workpiece. Turning involves rotating the workpiece around a stationary tool.
- Shapes Made: Turning is the best option for symmetrical, cylindrical parts.
- Tool Motion: Milling requires multi-axis tool movements; turning involves linear tool movements along the rotating workpiece.
- Applications: Milling can be used to produce detailed parts and is flexible. Turning is an excellent way to create round, precise components.
What is the difference between turning and milling?
Why choose CNC milling?
When your project requires:
- Complex Geometries： Milling is the best way to create intricate shapes, such as holes, slots, and cavities.
- Nonsymmetrical Parts: Milling is the most suitable option for parts with complex shapes that are not cylindrical. It is capable of handling diverse geometries, which turning cannot.
- Multi-Operations: Milling Machines can perform multiple tasks without moving the workpiece. This makes them ideal for parts requiring multiple features and operations.
- High precision and detail: Milling will provide the necessary accuracy and control if your project requires tight tolerances and fine detailing.
Why choose CNC turning?
When your project requires:
- Cylindrical parts: Turning can produce round or cylindrical components such as shafts and rings.
- Smooth Surfaces: Turning the surface is your best option for a smooth finish.
- Tolerances for Diameters: Turning can achieve precise diameters and lengths.
- Efficient Materials Removal： Turning is more cost-effective and efficient when dealing with large quantities of material removal.
CNC Milling and Turning Applications
Milling Applications
- Engine components
- Gear systems
- Connectors
- Surgical Instruments
- Support brackets
- Electronic enclosures
- Water pump housings
CNC Turning Applications
- Cylindrical shafts
- Precision nozzles
- Gun parts
- Ball joints
- Industrial rollers
- Turbine components
- Flanges for pipe and beams
Conclusion
CNC milling, turning, and other machining processes are vital for various industries and applications. CNC milling excels at creating complex and intricate parts, while CNC turning produces precision cylindrical components that are smooth. Understanding the strengths of each technique helps to select the best method for a specific manufacturing need.
Do you need a reliable sheet metal parts manufacturer? Shengen is the place to go. We specialize in sheet metal laser cutting, bending, surface finish, and CNC Machining. Reach out to Shengen Today and seek help from professionals!
FAQ
How accurate is CNC machining
CNC machining has a high degree of accuracy, allowing for tolerances as small as +-0.001 inch (+-0.025mm). CNC machines are capable of producing intricate and complex components with consistent quality.
What materials are suitable for CNC milling and machining?
The CNC milling or turning process can be used with a variety of materials, including:
- Metals: aluminum, steel, stainless, brass, copper and titanium.
- Plastics: ABS, polycarbonate (nylon), PEEK (acrylic), and others.
- Composites: carbon fiber, fiberglass, and other composite materials.
- Wood: Hardwoods, softwoods, plywood, and engineered wood products.
Can CNC machining be used for small-scale manufacturing?
CNC machining is suitable for small-scale production. Its flexibility allows it to produce small batches of custom-made parts efficiently.
More Resources:
CNC machining accuracy and tolerances – Source: 3ERP
Materials for CNC Machining – Source: Fictiv
Choosing the right end mill – Source: Mekanika
Hey, I'm Kevin Lee
For the past 10 years, I’ve been immersed in various forms of sheet metal fabrication, sharing cool insights here from my experiences across diverse workshops.
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Kevin Lee
I have over ten years of professional experience in sheet metal fabrication, specializing in laser cutting, bending, welding, and surface treatment techniques. As the Technical Director at Shengen, I am committed to solving complex manufacturing challenges and driving innovation and quality in each project.
