Introduction: The Central Contrast at a Glance
The most significant distinction between CNC turning and milling is which element is in motion. In the turning process, the workpiece rotates while the tool remains static. Conversely, in milling, the tool rotates while the workpiece stays static.
Envision CNC turning as a potter’s wheel where the clay spins while the potter shapes it. CNC milling, on the other hand, is similar to cutting with a Dremel, where the part does not move and the spinning cutter removes material.
Despite their differences, these two processes are still the most critical pieces in the modern manufacturing chain. Both CNC turning and milling are frequently utilized in tandem. The incorporation of both methods allows for the production of multifaceted and high-precision components.
Nearby Point: The CNC Turning Process in Focus
The Mechanism of CNC Turning
CNC turning is performed on a lathe, also known as a turning center. The machining workpiece is a round bar of material that is attached to a spinning clamp called the ‘chuck.’ The chuck uses the rotating material to spin at high speeds. A cutting tool is then brought into contact with the spinning material.
The installation of the tool in a turret is the main defining quality of CNC turning. The round shape is attained by the tool that removes the workpiece material. The process is programmed and monitored by a computer for very exact settings. Facings, groovings, and drilling holes are the main operations. The facing operation creates the flat end of the part. The grooving operation cuts channels in the part. Check the understanding of CNC turning for the detailed programming commands.
Normal Applications and Descriptions
CNC turning is primarily used in the processing of circular or cylindrical parts. The frontal symmetry that is achieved is thus excellent.
- Shafts and axles
- Pins and dowels
- Bushings and sleeves
- Custom fasteners like screws and bolts
- Any part with a main round or cone shape
Common Materials
Turning is capable of shaping a wide variety of materials with the selection being determined by the specific requirements of the final product. The factors that need to be considered in the process include strength, weight, and the chemical composition of the material.
We use a diverse range of materials in our company. The most frequently used are aluminum, stainless steel, brass, titanium, and variations of plastics including Delrin and PEEK. For your project, our CNC turning service can manage all these materials.
Nearby Point: The CNC Milling Process
Understanding CNC Milling
The milling machine is the key component of CNC milling. This machine looks like a machine tool for a single block of the material which is either a sheet or a bar with a fixed bearing. The rotating cutting bit in control spindle then moves multiaxis to cut this piece.
Three axes’ arrangements become a norm for the most popular machines: X (left-right), Y (forward-back), and Z (up-down). The advanced 5 machines are able to pivot the tool or the workpiece too. This helps to create very complex shapes in one operation. More about these advanced capabilities is available in a deep dive into the CNC milling process.
Regular Applications and Designs
CNC milling is suggested for workpieces characterized by flat surfaces, pockets, and slots, but it can also apply to complicated 3D shapes as well.
- Complex housings and enclosures
- Brackets and fixtures
- Gears and sprockets
- Molds and dies for injection molding
- Parts with flat faces, slots, and detailed 3D contours
Common Materials
As is the case with turning, CNC milling is able to handle a wide range of metals and plastics. The correct material selection is crucial. The material’s properties must be balanced with the application’s needs. Weight, durability, heat resistance, and cost are all major factors in choosing the right material for CNC turning and milling.
Versus: Side by Side Comparison
If you need to clarify, let’s contrast CNC turning and CNC milling directly. The most noticeable differences pertain to the form of the component and its required features.
| Attribute | CNC Turning | CNC Milling |
|---|---|---|
| Core Motion | The workpiece rotates while the tool stands still | Tool rotates, workpiece stays still |
| Typical Part Shape | Cylindrical, conical, round | Prismatic (square), flat, complex 3D shapes |
| Tooling | Stationary, single-point cutting tools | Rotating, multi-point cutting tools (end mills) |
| Axis of Operation | Usually 2 axes (X, Z) | Typically 3 to 5 axes (X, Y, Z + rotational) |
| Cost for Simple Parts | Lower for round parts | Higher due to complex setup |
| Best For | Shafts, pins, fasteners, symmetrical parts | Housings, brackets, molds, parts with pockets |
Both manufacturing processes boast high accuracy. It is worth noting here that both CNC turning and milling can deliver very tight tolerances. Precision diamenters in CNC turning can hold up to about ±0.001 mm due to the tolerance which is often crucial for high-performance features.
Decision Guide to the Right Process
At face value, choosing between CNC turning and milling seems a daunting task. However, based on some simple questions that are aimed at the design of your part, the best choice is possible. The following wisdom shall guide you through the question-and-answer process.
Question 1: What is the primary geometry of your part?
This is the major, core question. Examine the outer shape of your part.
In cases where the part is circular, conical, or cylindrical, it is advisable to initiate CNC turning. Moreover, the production of a round part by this method is by far the quickest.
However, if the part is mainly square, rectangular, or characterized by complex, non-symmetrical features, the start should be CNC milling since this process is the proper method to create those shapes.
Question 2: What secondary features are needed?
Now the details shall be dealt with. For instance, do you have any other features which should be placed in the off-axis position than the centreline in the part? These features may include off-axis holes, or flat faces, or slots.
If a turned part requires these features, some options are there. One could do it by turning the part on a lathe then shifting to a mill, or, alternatively do it by a multi-machine which has in it both the processes. This is the juncture where a decision about CNC turning and milling gets thrilling and more fun.
Question 3: What are your tolerance and surface finish needs?
Both techniques give excellent outcomes. They just shine in different areas. Turning, by its nature, provides a very smooth and even surface finish for round diameters, due to the spiral cutting. The continuous chip flow leads to a fine and spiral finish.
On the other hand, the milling process is outstanding when it comes to achieving a perfectly flat and smooth face. A machinist may find it overly complicated to achieve a perfectly round form using a mill compared to turning it on a lathe. However, it should be noted that the turning process would always be better for the primary, cylindrical elements.
A Quick Checklist for Your Decision
- Is the part round? Start with CNC turning.
- Are there flat surfaces, pockets, or 3D shapes in the part? You will need CNC milling.
- Does a round part need off-axis features like holes or slots? You will need milling capabilities, either as a second step or on a combined machine.
- Is the highest precision needed on a round diameter? Turning is usually superior.
- You can understand the complete CNC milling process to help determine if your complex features fall squarely in the milling category.
The Synchronicity of Both: Mill-Turn Centers
The distinct feature in “CNC turning and milling” lies in “and.” A lot of these parts are often incredibly complicated to produce by just one method. The solution comes from mill-turn centers.
A Mill-Turn Center is a Hybrid
A mill-turn center can be described as a hybrid machine. It is the CNC lathe coupled with CNC machining center; it is a powerful platform of two. It has a spindle which rotates the workpiece similar to a lathe. It also has a tool spindle that rotates for the purpose of milling.
This makes it possible for the machine to do both turning and milling on a part without the need to move it at any time. This is the best of both worlds!
The “One and Done” Advantage
When adding a mill-turn center, the benefits accrue massively to the complex parts. We term this approach as “one and done.”
- Better Accuracy: The component is not moved from one machine to another thus it reduces the chances of error in the setup, which in turn improves the accuracy of the final part.
- Reduced Lead Times: One single operation can finish the part, which is a faster way to produce and will get your products to you sooner.
- Complex Geometries: These machines create intricate products. For instance, the camshaft which has round bearing journals (turning) and difficult lobes (milling) represents the camshaft. The mill-turn machine can do this in one setup.
The Role of Swiss-Type Machining
For long, small, and complicated parts, there is an excellent form of turning called Swiss-type machining. These machines are a kind of turning center that often includes mill-turn capabilities. They are excellent for manufacturing tiny, precise components. For example, specialized Swiss CNC turning services offer unmatched efficiency and extreme precision in intricate components like those used in medical devices or electronics.
Conclusion: Responsible Smart Manufacturing Choice
Knowing the differences between CNC turning and milling is essential for you to find a good design and manufacture the same. Your decision concerns the component’s shape and features.
The main premise is almost homely: turning is for circular part and milling for parts with more intricate designs. In simple cases, the selection of the proper process may save you cash and time.
On the other hand, the most complex shapes often require a combination of CNC turning and milling. The advanced mill-turn centers are the ultimate cure for this, as they handle both in a single machine. By mastering the technicalities of both, you are a step ahead to lay out the design optimally and choose the right approach for yourself.
Check out a comprehensive portfolio of advanced manufacturing solutions at Mekalite.
Frequently Asked Questions (FAQ)
1. Is CNC turning or CNC milling more expensive?
It varies with the parts. For simple, round components like pins, or shafts, CNC turning is usually the more cost-efficient option. However, piping, or other similar parts with complex shapes, can be milled at a higher price than CNC turning because of longer technical and machine time. The most complex parts are often best priced on a mill-turn center since it handles it without adjustments that require time or cost.
2. Will a CNC mill perform turning operations?
Not in the traditional sense. A mill can subsequently produce a round feature with a path called “circular interpolation”. The tool moves in a circle. However, this is inefficient as compared to a CNC lathe that can create a long, perfectly round piece which is quicker to do.
3. What is “live tooling” on a CNC lathe?
Live tooling denotes the rotating cutting tools that can be mounted to a CNC lathe turret. This feature adds live milling, drilling, and tapping processes to a turning center, which essentially converts a normal lathe machine to a basic mill-turn machine. It broadens the machine’s capacity very significantly.
4. Which process is mass production faster?
This entirely relies upon the geometry of the part. Simple round parts in high quantities with CNC turning and an automatic bar feeder are extremely fast. Mass production of identical parts using an efficient CNC milling setup with several fixtures to hold the parts can also be remarkably rapid. The part’s design is always the deciding element in the right method.
5. What file format should I use for a CNC turning or milling project?
Typically, CNC projects are initiated with 3D CAD models. The most accepted and the most prevalent file formats are STEP (.stp/.step) and IGES (.igs/.iges). The software’s native files from SolidWorks (.sldprt) or Fusion 360 are also widely used. Besides, a 2D engineering drawing detailing the dimensions and the toleration is such an important tool for the final part to meet all the quality requirements.
