CNC milling and turning are precise and accurate manufacturing processes but with different applications. Without understanding both, you can choose the wrong one for your project. Hence, we will discuss the two CNC machining techniques so you can make an easier decision.
What is CNC Milling?
Firstly, CNC milling is a CNC machining technique. In CNC milling, you mount a rotating cutting tool on the milling machine and it removes material from a stationary block. You must note that the cutting tool rotates and the workpiece is stationary.
CNC milling differs from traditional/manual milling by its automation. Leading to error-free and consistent milling. As a result, unlike manual milling, pre-programmed codes (g-codes) guide the milling machines and determine parameters like speed, toolpath, and cutting depth.
CNC milling as a machining technique can produce complex and quality components, hence, its wide acceptance and recommendation to clients in the aerospace, automotive, and electronics industries.
Types of CNC Milling Operations
CNC milling has its subsets called CNC milling operations, each with its setup and capability. As a result, you can use the process in several ways in your project. The most common CNC milling operations are:
Face Milling
In face milling, the cutting tool or face milling cutter has interchangeable cutter inserts with multiple teeth. It rotates perpendicularly to the workpiece surface removing materials from it. Face milling is the best CNC milling operation if you want CNC-milled parts with good surface finishes.
Plain Milling
In plain milling, the cutting tool is parallel to the workpiece. As a result, you can use the CNC milling operation to make milled parts with plain horizontal surfaces. Nevertheless, you can feed the table longitudinally, cross, or vertically too.
Angular Milling
Angular milling is similar to plain milling with the difference being the angular setup, i.e., you mill using the cutting tool at an angle. You can use two cutters, one is the single-angle cutter with teeth on the cutter’s angular face and large flat sides.
The other is the double angular milling cutter with a V-shaped teeth and a conical surface. Based on the design you can use the first cutter to mill at angles of 45° or 60° and the latter to mill flat surfaces at 45°, 60°, and 90°.
Form Milling
If you want to make irregular contours on a workpiece, form milling is the best CNC milling technique. However, it is slower (about 20 to 30%) than regular milling by about 20-30% due to the intricacy of the operation.
Applications of CNC Milling Operations
CNC milling’s accuracy, precision, and tolerance are responsible for its wide range of applications in part manufacturing. You can get inspiration from the following industrial applications for your project.
Aerospace
The aerospace industry requires heightened accuracy, precision, and tolerance. As a result, when you are looking for the right process, CNC milling is the better CNC machining option. Furthermore, the process is compatible with materials like Aluminum used in the industry.
Automotive
The automotive industry also uses CNC milling for its accuracy, precision, and tight tolerance. The CNC machining technique is applicable in fabricating automotive components like the cylinder head, shaft, drive axles, and suspension components.
Agriculture
CNC milling machining is used in agriculture to make general-purpose parts and components like gear, shafts, and nuts and bolts.
Medical
The medical part manufacturing industry relies heavily on CNC milling because of its precision, accuracy, and capability to manufacture complex parts. You can use the machining operation for medical parts like prostheses
Advantages of CNC Milling
CNC milling has many advantages, some of which are listed below:
- CNC milling is accurate, precise which makes it consistent
- The machining technique can machine parts of different shapes, sizes, and materials
- CNC milling is flexible in terms of material compatibility which makes it suitable for several industries.
- Depending on the machine, you can have access to 5-axes and unlock better multi-faceted machining
- CNC milling is fast in prototyping and small batch production.
Limitations of CNC Milling
CNC milling has its limitations, some of which are listed below:
- CNC milling has a high initial and maintenance cost
- Setting up CNC milling machines can be time-consuming and complex
- It is not always effective for large, heavy components
- CNC milling tools experience wear over time, particularly when cutting hard materials.
- It is not an efficient CNC machining technique for making simple, non-detailed parts
What is CNC Turning?
In CNC turning, you use a machine mounted with a cutting tool to remove material from a rotating cylindrical workpiece. The technique is also compatible with other stocks, e.g., hex or square bars.
The main difference between CNC milling and CNC turning is the component that is rotating. In CNC turning, the turning machine spins the workpiece and the cutting tool removes material to form the desired shape.
Types of CNC Turning Operations
CNC milling also has its subsets called CNC turning operations, each with a setup and capability. The most common CNC turning operations are:
Facing
Facing is for cutting a flat surface perpendicular to the workpiece’s rotational axis. During the process, the facing tool will feed perpendicularly across the rotational axis of the part.
Turning
Turning involves removing material from the workpiece’s outer diameter either by being parallel to the rotational axis of the workpiece or at an angle to create a tapered part.
Boring
Boring involves feeding the cutting tool into an existing hole and using it to remove material from the hole’s inner wall.
Threading
You can use threading to cut threads into a hole or over the outer diameter of a workpiece.
Advantages of CNC Turning
CNC turning has many advantages, some of which are listed below:
- CNC turning is precise due to the use of an automated system
- The machining technique is versatile and capable of producing a wide range of parts
- It is safe which minimizes risks associated with manual turning machines.
- Production is smooth and efficient due to the fast operation
Limitations of CNC Turning
CNC turning has its limitations, some of which are listed below:
- CNC turning struggles with complex or intricate designs
- It may not be the best option for very hard metals or materials that need multiple cuts.
- CNC turning is limited to symmetrical shapes like shafts and pins.
- Even with automation, CNC turning tools can wear down over time.
- The initial setup and programming can take some time
Applications of CNC Turning Operations
CNC turning has wide industrial applications because of its precision and reliability. Here are examples of how you can apply the machining technique in different industrial sectors:
Aerospace
In the aerospace industry, you can use CNC turning for parts like turbine blades, bushings, and shafts using materials titanium and aluminum.
Automotive
CNC turning plays an important role in automotive manufacturing, particularly in producing components like engine blocks, pistons, and transmission parts.
Agriculture
In agriculture, you can use CNC turning to make machine components, like gears, shafts, and specialized fittings.
Medical
CNC turning is a good option for making medical parts like surgical instruments, implants, and orthopedic devices. The medical part manufacturing industry makes use of cylindrical components which can be made using the CNC machining techniques.
Comparison of CNC Milling and Turning
You can use CNC milling and turning for different projects but you need to understand both to get the best one for your project. We will compare both CNC machining techniques, discussing the differences and when to use each one.
Key Differences Between CNC Milling and Turning
CNC milling and turning differ in tool movement, setup, and complexity of the shapes they create amidst other differences. You should know these differences to pick the right one.
Cutting Tool Movement
The basic difference between CNC milling and turning is the cutting tool movement. In CNC milling, the cutting tool rotates while your workpiece stays stationary. On the other hand, in CNC turning, the workpiece rotates, and the cutting tool is stationary.
Workpiece Setup
Another important key difference is the workpiece setup. In CNC milling, you secure your workpiece on a moving table or spindle while in CNC turning, you mount the workpiece on a rotating lathe.
Number of Axes
CNC Milling uses 3 to 5 axes, which makes it flexible and precise. On the other hand, CNC turning uses a single axis (Z-axis), limiting the shapes you can produce. However, it is precise in manufacturing cylindrical components.
Speed and Efficiency
CNC milling is slower than CNC turning because it works on multiple axes. You can rely on CNC Turning for its speed and efficiency, especially in the mass production of symmetrical/cylindrical parts.
Applications
Use CNC milling for components with complex geometries, such as slots, pockets, and gears or custom housings. CNC Turning is the better option for cylindrical components, like shafts, pins, and bushings.
When to Choose CNC Milling and Turning
CNC milling and turning shines in different situations and your choice depends on your project’s specific needs. Here’s how to decide which process works best for you.
Part Geometry
For parts with complex designs, multiple flat surfaces, or 3D shapes, CNC milling is the better option. However, if you want to manufacture simple cylindrical parts, CNC turning is the better option.
Tolerance and Surface Finish
Use CNC milling for parts that need tight tolerances or a fine surface finish. CNC turning is the best option for parts with simple complex designs and cylindrical geometries
Production Volume
CNC turning is the most efficient in mass production of parts. For custom or smaller batch runs with complex shapes, CNC milling is the better option.
Tooling and Setup
CNC milling will require you to invest in more tools which can increase the cost of tools and in turn production. CNC turning when compared to the former however has a simpler setup and uses fewer tools. As a result, it is quicker for repeated tasks.
Bottom Line
You now have a better understanding of CNC milling and turning and which one to use. Use CNC milling for parts with complex geometries while CNC turning is better for cylindrical parts with simpler geometries. By understanding their differences, you can select the best one for your project needs.
FAQS
What’s the difference between CNC milling and CNC turning?
The primary difference between the two CNC machining techniques is in their tool and workpiece movement. In CNC milling, the cutting tool rotates and the workpiece is stationary, which is an opposite of CNC turning.
Which CNC machining technique is best for complex geometries?
CNC milling is the better technique for machining parts with complex geometries. The cutting tool rotates (the workpeice is stationary), increasing the number of points reachable on the workpeice.
Can I use milling and turning on the same part?
Yes, it depends on the part’s design and the desired specifications. A part with complex design and cylindrical feature will most likely require CNC milling and turning. In short, many parts will require milling and turning. Yet in some cases, some will need only one.
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